Air North Brasilia Crash in Darwin (Merged)

[Jabawocky]

Closer to the original topic...........................

Funeral for Shane W is Wednesday next week.

If you are interested check the local paper for details.

[Centaurus]

I've never seen anyone take two seconds to figure out it was time to stop with a failure, most folk have the thrust levers retarded within half a second. So figure another 30m or so if your failure happens ever so slightly under V1.

Having observed numerous rejected take off's in the 737 simulator it has been my experience that on almost every occasion the airspeed kept increasing by around seven to ten knots as the thrust levers were in the process of closing. This was regardless of speed of throttle closure. These were ordinary garden-variety pilots - not test pilots.

[JohnMcGhie]

A lot of speculation on the operation of the Brasilia prop.

A few pages of the simplified operation can be found at Smart Cockpit. This is dumbed down for pilots so may not tell the whole story, - but I suspect there may be a little more to it than some here appreciate.

SmartCockpit - Airline training guides, Aviation, Operations, Safety (http://www.smartcockpit.com/pdf/plane/embraer/EMBRAER-120/systems/0004/)
I struggled through a few pages of that. Is it just me, or is that incomprehensible gobbledy-gook? Well, no, it isn't just me: I am a Technical Writer by profession. I do stuff like that for a living. And that is attrocious: so bad it's dangerous.

The most fundamental requirement for technical writing is that it should be clear and unambiguous. That is neither.

I really hope that no poor pilot is trying to understand his aircraft by reading that! That material is dangerously bad.

If that is part of the real aircraft documentation, I would hope the ATSB could spare a couple of paragraphs in its report to make a finding on that document. :eek:

http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/buttons/reply_small.gif (http://www.pprune.org/newreply.php?do=newreply&p=5595835&noquote=1)

[remoak]

Having observed numerous rejected take off's in the 737 simulator it has been my experience that on almost every occasion the airspeed kept increasing by around seven to ten knots as the thrust levers were in the process of closing. This was regardless of speed of throttle closure. These were ordinary garden-variety pilots - not test pilots.

OK well maybe it's a cultural difference. Having observed a large number of RTOs in the 146 sim, I have never seen a pilot take more than a fraction of a second to close the thrust levers, but then we always taught that they should be retarded firmly and rapidly. I don't know why you wouldn't just slam them shut, but maybe you have a different slant on that with the 737.

How an engine keeps on producing enough power to accelerate the aircraft when it's only receiving enough fuel for ground idle escapes me though...

[Chimbu chuckles]

How about momentum and inertia?

That the Fischer Price Starlifter gets to V1 at all is a mystery of aviation right up there with sustained flight & Bumblebees :ok::E

Yes I have flown them:}

[remoak]

How about momentum and inertia?Oh sure any engine has both of those properties, however acceleration only happens if fuel is being burnt in sufficient quantities to overcome drag and fulfil Newton's Third Law. That ain't happening at ground idle.

Not really a point worth arguing over though.

You would diss the Queen of the skies? :=:}

[ravan]

Interesting that Ron Lawford is prepared to put a price on a pilot's life when he suggests that it is cheaper to do rating renewals and line checks in the aircraft rather than find a sim.

I understand the short term economics for smaller companies but cannot appreciate the big picture "myopia". It is not a matter of "if" so much as a matter of "when" the next accident of this type will occur.

Affordable Safety at work.....all right in the vast majority of cases but not so safe or affordable if you happen to be the exception.

[tail wheel]

What is actually stated is:

RON LAWFORD, VETERAN TERRITORY PILOT, DARWIN: It's a matter of economics where for some people it's cheaper to use the real aeroplane to do the instrument rating renewal, to do the recency checks, than to find a simulator which may be on the other side of the world and fly their pilots to that place to do the, the one or two hours of flying in the simulator.

I don't think that is exactly putting.....
".....a price on a pilot's life when he suggests that it is cheaper to do rating renewals and line checks in the aircraft rather than find a sim."

Appears to be a statement of fact rather than a personal opinion.

[relax737]

Ron's old school; I think he flew DC3's inthe RAAF a hundred years ago, and from some of the training I saw at the Aero Club in a Partenavia,real heroic stuff ove at D212, I wouldn't put a lot of store in what he says.

What concerned me greatly is that the ABC is prepared to listen to the guy who runs the RMIT flight school at Pt Cook, who is a private pilot. Why don't journalists do just a little research into who they're talking with before putting this crap to air??

I think I know the answer, and it's that 99% of the viewers don't know what they're listening to so it's not all that important. I did think the ABC may have been a little more discriminating though.




I seriously doubt all the following are not qualified to make competent, professional comment:

AIR TRANSPORT SAFETY BUREAU:
MICHAEL BRIDGE, AIRNORTH CEO:
BILL HAMILTON, RETIRED QANTAS PILOT, SYDNEY:
JOHN HARDY, HARDY AVIATION CEO, DARWIN:
RON LAWFORD, VETERAN TERRITORY PILOT, DARWIN:
BOB DUDDINGTON, RMIT, MELBOURNE:

We're not turning this thread into another media bashing thread! :=

Tail Wheel

[AerocatS2A]

There's nothing wrong with what Ron is saying. That it is cheaper for some companies to do their training in an aircraft instead of sending their pilots to a sim somewhere is hardly an earth shattering statement. He's not saying it's right, he's saying that's how many companies see it.

[triadic]

Ron's old school; I think he flew DC3's in the RAAF a hundred years ago, and from some of the training I saw at the Aero Club in a Partenavia,real heroic stuff over at D212, I wouldn't put a lot of store in what he says.

Yes, Ron is old school, and tell me what is "wrong" with that. There are many pilots about that have significant experience in many fields of operation and Ron is one that has been a total aviation person and professional for all of his flying career. So what if it started with DC3's? Yes, his training methods were at times strict, but he helped produce good pilots. His knowledge and skills, even at his present age, I suggest would be up there with the best.

Part of the problem which has not been raised fully in this discussion is the type of training that training pilots get these days. I was a former Instructor and that helped me considerably during the training part of my career when there was no sim and all the flying had to be undertaken in the aircraft. Sound planning and conservative scenario's provided the basis for training in the aircraft that was a safe as possible.

Later in my career I was with a company where the training and checking pilots were selected often on the basis of being mates with the boss or CP, not their ability to impart knowledge. This reflected down the line when one found out what new F/Os were not taught! Sadly at the time CASA could not give a rats and just endorsed the company selection. With the advent of the sim, the training was still deficient because the 'old guard' experience was not often there to cover off what many believe to be the basics.

Now many of the "basics" are just not taught! We could start with airmanship and what those pedals on the floor are for!

These comments are generic and do not relate to this tragic accident, the company or crew involved.

[RENURPP]

Later in my career I was with a company where the training and checking pilots were selected often on the basis of being mates with the boss or CP, not their ability to impart knowledge. This reflected down the line when one found out what new F/Os were not taught! Sadly at the time CASA could not give a rats and just endorsed the company selection. With the advent of the sim, the training was still deficient because the 'old guard' experience was not often there to cover off what many believe to be the basics

unfortunately still the case. Human nature I guess

[F.Nose]

Does anyone know the actual method for calculating V1 on the Braz? and Is it possible to get it wrong?

Not suggesting that was the problem here, just curious.

[privateer01]

Least in a DC-3 one learned how to use thier feet......

Not saying that was the case in this instance.

Just saying....

[vee tail]

In this category all V1,Vr and V2 are taken from RTOW charts in the A/C generally in a book next to the seat or the ships library, it is possible to get it wrong however at these weights a couple of knots here or there will only make a difference if you are a test pilot. The A/C will accererate that quickly and I tend to think even 1 inop ( unless auto feather failure hasnt occured and yes there are other things that can go wrong ) the machine powers away very well. Actuals are rarely used as assumed temps are generally the go.

:ok:

[Chimbu chuckles]

Thirdly, deceleration starts as soon as you close the thrust levers

No, Remoak.

At the instant that thrust is removed the rate of acceleration starts to decrease but actual deceleration starts some period of time later.

If an aircraft is being accelerated at say 10m/sec/sec it doesn't instantly go to -1m/sec/sec but rather experiences an acceleration rate of 9/8/7/6/5/4/3/2/1 m/sec/sec first.

It may FEEL like deceleration but its actually reducing acceleration.

[404 Titan]

remoak

I’m not sure what aircraft you fly and/or whether it has a full EFIS setup but the last time I was in the sim the Speed Trend arrow on the speed tape of my PFD didn’t go from acceleration to deceleration in an instant. It did exactly as Chimbu Chuckles has stated. The acceleration decreases over time once the power is reduced or removed before the aircraft started to decelerate.

[ace from space]

f.nose
Does anyone know the actual method for calculating V1 on the Braz? and Is it possible to get it wrong?

Not suggesting that was the problem here, just curious

Most operators have TOLD (TO and landing data cards) cards kept within reach in the cockpit. Usually speeds determined in increments of 250kg or 500lbs, so some small rounding errors are possible but would only make a difference of a knot or so....no biggy!

[ace from space]

remoak
Again, using the 146 as an example, if you take off using flex thrust (as you normally would at training weights), there is no requirement to increase thrust to N1ref if you suffer an engine failure. You can if you want, but you don't have to as the flex thrust performance allows for the engine failure case. So for the 146, you have even less of an issue with controllability as the assymetric thrust is lower than it would be with full thrust.

To be fair, comparing an engine failure in a four engine jet with a two engine turbo prop is not comparing apples with apples.

[AerocatS2A]

Chimbu, if there is no thrust there is no acceleration. There is no requirement for acceleration to reduce gradually. Movement is subject to inertia and momentum but acceleration is not. Any perceived delay in deceleration would be due to delays in the engine responding to power lever inputs.

404Titan, with your speed trend you are seeing delays in engine response, the engine will not go from T/O thrust to idle instantly. The statement that acceleration stops the instant the thrust levers are closed is wrong because the engine can't respond that quickly, but if you think that you can remove all thrust and still experience positive acceleration then you are also wrong.

[F.Nose]

[QUOTE]Chimbu, if there is no thrust there is no acceleration. There is no requirement for acceleration to reduce gradually. Movement is subject to inertia and momentum but acceleration is not. Any perceived delay in deceleration would be due to delays in the engine responding to power lever inputs/QUOTE]

I beg to differ.

It depends on the mass of the object and rate of acceleration.

Think of a bullet being fired from a gun. The bullet is initially at rest until a charge is applied and it then accelerates until equilibrium is achieved before starting to decelerate. Thrust is removed the moment the bullet leaves the barrel however at that point it is still accelerating.

[AerocatS2A]

Thrust is removed the moment the bullet leaves the barrel however at that point it is still accelerating.
Have something to back that up? You can't accelerate something if you don't have a force applied, aside from gravity, a bullet doesn't have any positive acceleration force applied after it leaves the muzzle (it has plenty of negative acceleration in the form of friction.)

I'll do your work for you.

Acceleration = force/mass (a reworking of the old F=M/A)

If you have no force then acceleration is zero. If you'd like to explain what positive horizontal force is being applied to a bullet after it has left the barrel, I'll be interested to read it.

[remoak]

Chimbu

No, Remoak.

At the instant that thrust is removed the rate of acceleration starts to decrease but actual deceleration starts some period of time later.

If an aircraft is being accelerated at say 10m/sec/sec it doesn't instantly go to -1m/sec/sec but rather experiences an acceleration rate of 9/8/7/6/5/4/3/2/1 m/sec/sec first.

It may FEEL like deceleration but its actually reducing acceleration.Nope sorry, you are utterly wrong on this. I think maybe you misunderstand the meaning of acceleration - which is defined as a rate of change, not just a change.

As soon as you remove thrust, the speed may appear to increase slightly - but the rate of change is negative (ie a deccelaration). You have alluded to this yourself in the figures you quoted in your post. As acceleration is a vector quantity, as soon as the vector (or rate of change - not just change) starts to reduce, the acceleration becomes negative.

And if you disagree with that, you would need to be able to explain how an object being accelerated can continue to do so when the accelerating force is removed. Inertia doesn't do it; all inertia does is slow the rate of acceleration (or decceleration). Remember, a decrease in the rate of acceleration is actually a decceleration - it is a negative vector.

If you don't believe me, try hanging some fluffy dice from your wet compass. If you accelerate forwards from rest, the fluffy dice will head rearwards - the angle of the string indicating the rate of change. The harder you accelerate, the greater the angle on the string. The proof that the angle of the string is indicating acceleration is that if you stop accelerating and continue moving at a steady speed, the fluffy dice will hang vertically again (ie no angle on the string, therefore no acceleration therefore equilibrium). Going back to our example, if you then remove the power and hit the brakes, the fluffy dice (subject to whatever small inertia they possess) will immediately start to move forwards. The acceleration (as indicated by the angle of the string) immediately reduces (implying negative acceleration or decceleration). The speed will continue to increase for as long as the string is rearwards of vertical, which is never going to be more than a very small fraction of a second.

Any increase you are seeing on the instruments has more to do with lag in in the system than an actual physical increase in speed.

404 Titan


I’m not sure what aircraft you fly and/or whether it has a full EFIS setup but the last time I was in the sim the Speed Trend arrow on the speed tape of my PFD didn’t go from acceleration to deceleration in an instant. It did exactly as Chimbu Chuckles has stated. The acceleration decreases over time once the power is reduced or removed before the aircraft started to decelerate. A speed trend arrow is a PREDICTION, not an actual rate change, and isn't reliable in the abort case because the system is simply not set up to measure the extreme velocity change accurately.

ace from space

To be fair, comparing an engine failure in a four engine jet with a two engine turbo prop is not comparing apples with apples. The same principles apply in a turboprop. Those that don't have a reduced thrust schedule, normally have a thrust augmentation system (ie water meth in the F27 or some J32s).

Besides, a two-engine go-around in the jet is probably just as difficult... ;-)

F.Nose


It depends on the mass of the object and rate of acceleration.

Think of a bullet being fired from a gun. The bullet is initially at rest until a charge is applied and it then accelerates until equilibrium is achieved before starting to decelerate. Thrust is removed the moment the bullet leaves the barrel however at that point it is still accelerating. The mass of the object is what gives it inertia. Acceleration is itself a rate, so to be pedantic you can't have a rate of acceleration (which would be the rate of the rate of change of velocity).

As mentioned above, acceleration is a vector quantity. As soon as the bullet leaves the barrel, the velocity may increase slightly (but only slightly), but the rate of change of velocity (which is what acceleration is) immediately reduces. Think about it - it has to. There is no thrust and lots of drag - the bullet has no choice but to slow down, and more to the point there is no way that the rate of change of velocity can increase when there is no accelerating force...

Looking at it another way, equilibrium is achieved when thrust=drag. This occurs for a very brief instant at the end of the barrel. After that, only deccelaration is happening.

If you have found a way to get the bullet to accelerate when there is no accelerating force, you have basically invented perpetual motion!

[F.Nose]

Hmm yes good argument.....I concede.

[mattyj]

:confused:the universe is expanding at an increasing rate!!??

[remoak]

Yes it is, but only because there is a force driving it to do so... but I'm not sure a discussion of dark energy and cosmological constants is appropriate for this forum... :}:8

[john_tullamarine]

Some interesting posts and worth discussion for the benefit (especially) of the newchums ..

the certification requirements of the aircraft allow for that (2 second recognition time).

only relevant to post A/L 42 certifications. Earlier certifications still are a MOST critical animal when it comes to achieving ASDR.

deceleration starts as soon as you close the thrust levers

afraid you will need to read up a bit in the literature. This is NOT the case, especially for the higher bypass engined aircraft. Throttle chop certainly commands a reduction in thrust. However, as others have pointed out, the engine run down characteristics result in an increase in speed (ie still accelerating) while the thrust sorts itself out, eventually resulting in a deceleration.

If you do exceed V1, it will be by very little.

afraid this is not the case .. Centaurus' figures are not atypical.

I've never seen anyone take two seconds to figure out it was time to stop with a failure, most folk have the thrust levers retarded within half a second.

in the training/checking environment .. of course .. we are all ever so primed for the known-to-be-coming failure that we are ace-of-the-base onto the throttle chop.

On the line, the startle factor historical record proves the need for A/L 42 and, probably, a bit more on many occasions ...

If Vmcg is controlling, you are on the ground, right? That is what Vmcg means.

yes ? and, if this is the situation, you can still end up heading seriously towards the weeds off to the side of the runway in a few blinks of an eye

So in that situation, you control the yaw with asymmetric brake.

basic tenet of certification is that there is no change in thrust or use of braking. If you need to use the brakes .. then you should be stopping rather than trying to recover an already out of control situation

Whatever happened to lowering the nose to, at the worst, maintain level flight while you accelerate?

no real use to the pilot .. in the post departure situation, if you don't reduce thrust .. then it just gets worse .. quickly. Once you reduce thrust, you have some reasonable chance of recovering the situation by accelerating during a descent until you get to a speed at which you can use useful levels of thrust. Mind you .. if you are over the upwind threshold at 100 ft or so ... it probably remains an academic consideration for the Monday morning quarterbackers .. the pilots, generally, being dead shortly thereafter ...

The only time I can see that you would be correct is if you had an unfeathered prop or a similar failure.

that just makes a bad situation worse .. only a matter of degree, not fact.

Of course, if you are talking about GA aircraft at high weights, then sure.

works the same for heavies .. the physics is still the same

With the 146 (and the F27 too I think), under JAA-approved manuals, it was permissible to fly the engine-out departure profile at a speed higher than V2 if that speed had been achieved and the minimum climb gradient was being complied with.

probably never got into the rule book but commonly used as a protocol at operator level .. simply reflects the fact that min V2 is well below the best climb performance speed so, if you are going faster, there is not much point slowing down (caveat - unless a terrain critical escape has turn radii predicated on a scheduled speed)

if you were at training weights, it is actually pretty hard to stop the speed running away a bit while still maintaining a reasonable rate of climb

perhaps you are missing the point of the discussion. If you are fast enough for a yaw departure to be irrelevant, fine .. if you are too slow, you are into a departure and there will be no option to accelerate your way out of a world of hurt .. the thrust just winds you up into a tighter ball in the weeds off to the side of the runway/extended centreline

OK, but I can't think of any transport-category aircraft that wouldn't either accelerate quickly through the danger zone you are describing, or allow a power or pitch reduction to regain control while still climbing away quite happily.

refer to the comments above. The only aircraft which are reasonably bulletproof are those with an ultra low Vmcg/Vmca .. Citation comes to mind.

Main problem is that, unless you have been there or seen it happen, it is difficult to comprehend just how fast the beast can get away from the pilot. I have some interesting Vmcg video footage tucked away somewheres in the archives which opened my eyes .. WIDE .. at the time I first had some involvement with such testing.

The reason I say that it is theoretical, is that you never need to get into that position in the first place.

unless you are in a typical aircraft at min weight using standard min schedule speeds ... and then you are smack bang right in the middle of the problem if you have any hiccups or other problems ..

if you take off using flex thrust there is no requirement to increase thrust to N1ref if you suffer an engine failure.

true, but not particularly relevant to the discussion

I would be interested to know what aircraft you are thinking of when you mention these difficulties.

most of them

Does anyone know the actual method for calculating V1 on the Braz? and Is it possible to get it wrong?

a long time since I have done any work on the -120 so the specifics are a bit rusty. However, speed calculations are conventional .. error potential is no different to other conventional AFMs or RTOW charts developed from the AFM

if there is no thrust there is no acceleration

.. yes ... however, when you chop the operating throttles, there is an engine run down characteristic to take into account .. it DOES take a while for the acceleration to become a deceleration and there WILL be a modest speed increase associated with that sequence

Any increase you are seeing on the instruments has more to do with lag in in the system than an actual physical increase in speed.

afraid this is not the case .. the speed peaks a tad after the throttle chop occurs ... the larger delta occurring for the bigger fan engines

the universe is expanding at an increasing rate!!??

apparently .. but my head hurts when I read those books ..

[Centaurus]

That ain't happening at ground idle

True statement except the engines never get to ground idle the instant the throttles hit the stops - they take several seconds to run back - in fact about 10 seconds to reach ground idle from throttle closure from take off power.

[Chimbu chuckles]

Nope sorry, you are utterly wrong on this.

Wouldn't be the first time, won't be the last:ok:

I still think that it will take time for drag to overcome the physical acceleration and actually cause deceleration. I agree that the acceleration force is - the instant after thrust is removed but that is not the same as saying the object slows down instantly rather than continuing to pick up a little more speed before physically decelerating. 100 tonnes is going to want to keep doing what it was doing longer than fluffy dice.

Maybe you're correct and all we see is instrument lag - in fact that is ringing a vague bell in a dusty, rarely used section of my grey matter.

Thanks for challenging me to think a bit harder on it.:ok:

[remoak]

afraid you will need to read up a bit in the literature. This is NOT the case, especially for the higher bypass engined aircraft. Throttle chop certainly commands a reduction in thrust. However, as others have pointed out, the engine run down characteristics result in an increase in speed (ie still accelerating) while the thrust sorts itself out, eventually resulting in a deceleration.


Like I said... acceleration is a RATE thing, not just a direct measurement of speed increase. The speed might increase slightly as the thrust level takes time to fall below that required to overcome drag - particularly on a FADEC engine. The speed might be increasing slightly, but overall there is a deceleration.

afraid this is not the case .. Centaurus' figures are not atypical.

What you are SEEING on the instruments is not necessarily what is actually happening, for a variety of reasons... see Chimbu's post. There is lag in most pitot-static based systems.

yes ? and, if this is the situation, you can still end up heading seriously towards the weeds off to the side of the runway in a few blinks of an eye

Maybe, but I really can't see why you wouldn't have the taps closed and the brakes/antiskid/spoilers doing their thing. I'm having trouble with the idea that you could ever get into that situation in the first place. Vmcg is never going to be above V1, and is usually well below it. So if a failure has occurred below Vmcg, you are (unless you are Centaurus) going to stop. I am still wondering what aircraft you are thinking of, because even the F27 will accelerate quickly through that particular danger area with an engine out.

basic tenet of certification is that there is no change in thrust or use of braking. If you need to use the brakes .. then you should be stopping rather than trying to recover an already out of control situation

Why would you be trying to GO from below Vmcg?

Once you reduce thrust, you have some reasonable chance of recovering the situation by accelerating during a descent until you get to a speed at which you can use useful levels of thrust.

I am still wondering what aircraft you are thinking of. All the turboprops I have flown will quite happily accelerate (assuming that you rotated at the correct speed) and climb away, at training weights anyway (which is what we are talking about). Again, going back to the F27, in the sim we could never induce a loss of control if the correct speeds were flown. The only way to do it was to fail an engine on finals - it won't autofeather, and if the crew forget to manually feather it, you gradually get lower and slower until you end up with full power on the live engine, full rudder, full aileron, and seconds later an inverted aircraft and a (simulated) smoking hole. But that is a gradual process.

perhaps you are missing the point of the discussion. If you are fast enough for a yaw departure to be irrelevant, fine .. if you are too slow, you are into a departure and there will be no option to accelerate your way out of a world of hurt .. the thrust just winds you up into a tighter ball in the weeds off to the side of the runway/extended centreline

No, I don't think I am. Being fast enough to avoid a yaw departure means, basically, being above Vmca. if you are flying the departure correctly, there isn't really a reason not to be well above that speed. From memory, the difference between V1/Vr and V2 on an unrestricted runway in the F27 was seldom more than about five knots. That would be typical of most turboprops. I can't think of any turboprops that would have trouble getting to V2 if they rotated at Vr, and once you are at V2 there is no reason that I can see for a yaw departure to occur. if you mis-handle the departure, maybe, but that isn't what we are talking about.

works the same for heavies .. the physics is still the same

The physics might be the same (although it isn't really, as inertia is more of a factor in heavies), but the certification requirements aren't, and most GA twins are far more marginal than most transport-category turboprops.

probably never got into the rule book but commonly used as a protocol at operator level

It (flying an achieved speed) did in Europe, but yes probably not in Australia.

.. yes ... however, when you chop the operating throttles, there is an engine run down characteristic to take into account .. it DOES take a while for the acceleration to become a deceleration and there WILL be a modest speed increase associated with that sequence


It does take a little while for an engine to run down (as the core has inertia), but that doesn't mean that it is producing any meaningful thrust. Thrust isn't a product simply of rotational speed, it is primarily a function on the amount of energy being produced by the burning of fuel. Remove the fuel, and you remove most of the energy. Anyway, as soon as the rate of increase of velocity peaks, you have deceleration (by definition). You simply can't have an acceleration if thrust is reduced below that necessary to counter drag (and one assumes, brakes) - sorry, that's simple physics. I am still of the opinion that most of what you are seeing as a speed increase is actually instrument error... but I would love to see some hard facts on that whole subject. Anyone?

Centaurus

True statement except the engines never get to ground idle the instant the throttles hit the stops - they take several seconds to run back - in fact about 10 seconds to reach ground idle from throttle closure from take off power.

Sure, but as noted above, as soon as you remove the fuel (by closing the thrust levers), the engine stops producing meaningful thrust. There will be a little residual thrust, but most of it is being absorbed by the rotating mass of the engine (Newton's Third Law again). Whatever thrust there is, is highly unlikely to be enough to counter drag and inertia sufficiently to produce a significant speed increase. Think about it - if you launched down the runway at say, 25% thrust, would you ever get to V1? Probably not... and an idling engine is probably producing no more than 10% thrust. There is no way that an engine that is only receiving enough fuel to produce 10% thrust, is going to accelerate the aircraft it is bolted to at anywhere near the levels of drag it will be experiencing near V1.

I'm happy to be proved wrong, but only if you supply evidence... :ok:

[43Inches]

Acceleration will only occur if forces are not in balance, on take-off thrust is much greater than drag, therefore rapid speed increase is the result. The moment thrust is removed acceleration will stop. Inertia will only affect the present motion of the aircraft at that time, it can not cause an object to change speed or direction in any way. Acceleration will only continue as a result of the slow spool down of the engines, depending on type it may continue to produce positive thrust for a few more seconds after ground idle is selected.

Removed missleading rubbish regarding certification...

[Mainframe]

This thread has evolved into one of the best technical discussions on assymetric operations.

Out of tragedy, much will be learned and incorporated.

My area of experience is GA twins, not transport category turbo prop twins.

When sitting in the right hand seat, about to fail an engine during training, checking or an endorsement,
I recognise that EFATO drills in a GA twin have a high risk factor.

Was the exercise adequately briefed, is it a long runway or a short runway, will the gear be up or in transit, flaps position etc.

The accident and the accompanying fatality rate in GA twin assymetrics makes sobering reading.

The training is meant to be eventually life saving, yet too often it becomes life threatening.

Vmca demos should and are demonstrated at a safe height, and to some degree initial EFATO drills can also be carried out at or above 3,000 ft.

When a satisfactory level of demonstrated competence is established, it may be beneficial to conduct actual simulated failures off the runway.

There will be a high degree of risk, and prudence may dictate waiting until gear retracts before failing the engine, depending on type.

Simulators are preferable for obvious reasons of safety, but PA31, C402, C310, BE58, BN2, P68 etc simulators
that can adequately be used for this exercise are either not available in Australia, or very rare.

By continuing this excellent technical discussion we are helping to ensure that some benefit will come out of this tragedy.

[ace from space]

Mainframe


This thread has evolved into one of the best technical discussions on assymetric operations.


Yes I agree, it has turned into a worthy technical discussion. The thread has got off the original posted subject, but there is nothing further to be gained by speculation or ‘quarter backing’.
However there is much to be gained by sharing experiences and ideas that may help prevent a future tragedy occurring.:ok:

[ace from space]

remoak
The same principles apply in a turboprop. Those that don't have a reduced thrust schedule, normally have a thrust augmentation system (ie water meth in the F27 or some J32s).

Yes true, the same principles still apply, however I proffer that the handling technique may well be quite different.
The Brasilia does have a reduced thrust schedule and typically during training we’d set around 80% Tq (79% being min Tq from memory) on T/O to simulate a loaded a/c. From my experiences it was not necessary to increase thrust during a simulated engine out T/O, but reserve thrust was available up to 120% Tq (time limited) and beyond 120% if you still really needed it (emergency use only).
So power per say or the ability to climb away on one, was never the issue.
With the big 4 bladed carbon fibre blades on this bird, there was a big difference in managing a critical engine failure (#1) as compared to a #2 engine failure and required sound technique to maintain directional control. As I have commented previously, you could sometimes find yourself surprised at the amount of control inputs required on the critical failure case, so there was a considerable difference between the two ‘engine out’ exercises.
I haven’t flown the F27 so can’t comment on any differences in handling or performance between the two a/c.

[privateer01]

As I have commented previously, you could sometimes find yourself surprised at the amount of control inputs required on the critical failure case,

Yeah takes pretty much full Rudder travel at Vmca? :E

[remoak]

I haven’t flown the F27 so can’t comment on any differences in handling or performance between the two a/cThe main difference is that the F27 has little performance compared to modern aircraft and requires finesse at high weights and temperatures to avoid becoming one with the landscape.

Certainly in Europe, the F27 would never be certified if it was introduced as a new type - it simply doesn't have the performance margins.

The F27 does have a thrust reduction schedule - kinda - via the fuel trimmers. Nothing like a modern turboprop though.

[privateer01]

Might have been this one:

Title: Light Twin Engine Aircraft Accidents Following Engine Failures, 1972 - 1976.
NTSB Report Number: AAS-79-02, adopted on 12/13/1979
NTIS Report Number: PB80-177306

Link: http://libraryonline.erau.edu/online-full-text/ntsb/aviation-special-studies/AAS79-02.pdf

Might be on page 15 or there about.

[privateer01]

Or this one has it in Percent.

Link: Always Leave Yourself An Out (http://www.iflypete.com/documents/Always_Leave.html)

[maggotdriver]

Good discussion, however, I will have to put my 2 cents worth in.
Remoak, consider if you accelerate in your car to 100km/h, where you enter a steady state at 100km/h. The last part -say from 90 to 100 km/h - isn't deceleration, it is a reduction in acceleration until you are in a steady state, i.e. equilibrium. Consider also a propellor loss on an aircraft, it doesn't stay on the shaft until landing. Indeed it departs at a great rate as the rotating momemtum has to be brought also to a state of equilibrium before the dynamic pressure could hold it in place. Condolences to the families.

[remoak]

Well the discussion on acceleration is probably a diversion that isn't really worth the time... however... just to finish it off..

consider if you accelerate in your car to 100km/h, where you enter a steady state at 100km/h. The last part -say from 90 to 100 km/h - isn't deceleration, it is a reduction in acceleration until you are in a steady state, i.e. equilibrium.That's fine - because in that case, thrust isn't removed, it is just reduced until thrust=drag (to put it crudely). Not the same thing at all as taking your foot off the throttle. You could argue that a car engine behaves in the same way as a high-bypass gas turbine (ie the effect of inertia), however as discussed inertia will not produce an acceleration (well it will, but in the opposite direction).

Consider also a propellor loss on an aircraft, it doesn't stay on the shaft until landing. Indeed it departs at a great rate as the rotating momemtum has to be brought also to a state of equilibrium before the dynamic pressure could hold it in place.No... it leaves the shaft because a) it has inertia; and b) the aircraft suffers a negative acceleration due to the loss of the thrust of the prop (ie it slows down a bit). Nothing to do with the other case at all.

As I said before, if you can make a suddenly-free prop accelerate (positively) when there is absolutely no power being applied to it, you have invented perpetual motion. Can I buy shares in your company? :}

[john_tullamarine]

The speed might be increasing slightly, but overall there is a deceleration.

if we take the failure point acceleration as reference then, of course, there is a subsequent deceleration. However, if you take an earth based reference, there is a progressive reduction in acceleration (during which the aircraft is still increasing its speed relative to the reference frame) eventually ending in a deceleration and the speed reduces .. is this not really a vital consideration for the discussion ?

What you are SEEING on the instruments is not necessarily what is actually happening,

reality dictates that your observation is incorrect, I'm afraid. I would be a bit concerned if the ASI were such an unreliable gadget ..

for a variety of reasons

perhaps you might list the variety of reasons to which you refer ?

Maybe, but I really can't see why you wouldn't have the taps closed and the brakes/antiskid/spoilers doing their thing.

during a local exercise (sim/aircraft) the pilot is primed and hot to run with a reject .. knowing that the problem is coming.

Reality on the line is quite different and startle factor has to be contended with .. it is for this sort of consideration that A/L 42 was introduced

I'm having trouble with the idea that you could ever get into that situation in the first place.

if all goes well and the speed/thrust situation puts you above the real Vmcg/Vmca .. fine.

However, the book figures are just that .. reference data for specific circumstances.

Change the circumstances and the values change .. consider, for a min weight, min speed schedule takeoff and a reasonably aftish CG ..

(a) significant adverse crosswind and there goes book Vmcg out the window .. something in the order of 0.5 kt/kt (twin) to in excess of 1.0 kt/kt (quad) increase in Vmcg .. and away you go into the weeds off the side of the runway.

(b) higher than certification thrust .. likewise for both Vmcg and Vmca

(c) out of left field drag situation on the failed engine .. failure of the NTS/autofx/decouple/whatever system ... likewise for both etc ..

(d) bank miscontrol in the air .. Vmca is VERY bank dependent. For instance, a well known lots of engines strategic bomber, as I recall, has a Vmca delta of around 43 kt if the bank is 5 degrees into the failed engine .. maybe it was 34 kt ? ... long time ago now since I did that course ... and the memory is a bit scratchy on the specifics ... either way .. a lot of knots however you look at it ..

.. need I go on ?

Vmcg is never going to be above V1

see above ... realworld Vmcg can be quite different to book Vmcg on the day if things aren't going your way ... if that happens to be above V1 .. and that's not hard to have happen for a min weight min speed schedule takeoff .. then the pilot can find himself in a whole world of hurt.

if a failure has occurred below Vmcg, you are (unless you are Centaurus) going to stop.

thank heavens for that .. knowing Centaurus as well as I have over the years, I suggest that he will be quite aware of his closeness to Vmcg and tailor his management strategies accordingly...

I am still wondering what aircraft you are thinking of

still most of them ..

even the F27 will accelerate quickly through that particular danger area with an engine out.

now, I had three years of great fun on the Friendly .. but it, the same as most other aircraft, WON'T accelerate through the problem area if, for whatever reason, the aircraft has already departed in yaw ... keep thrust on and you just wind yourself into a tighter ball in the weeds ...

Why would you be trying to GO from below Vmcg?

I wouldn't.

The discussion relates to the situation when, for whatever reason, the pilot finds himself below the real world Vmcg on the day

I am still wondering what aircraft you are thinking of.

I'm still thinking of most aircraft ..

All the turboprops I have flown will quite happily accelerate (assuming that you rotated at the correct speed) and climb away, at training weights

refer to the above discussion re real world Vmcg/Vmca

But that is a gradual process.

granted .. but, for an equivalent sort of problem on takeoff there is nothing very gradual about the departure ...

Being fast enough to avoid a yaw departure means, basically, being above Vmca.

or Vmcg according to where you are on the takeoff ..

if you are flying the departure correctly, there isn't really a reason not to be well above that speed.

.. providing that the book speed hasn't been corrupted on the day due to unforeseen circumstances ...

once you are at V2 there is no reason that I can see for a yaw departure to occur.

as before, for a min weight, min speed schedule .. if the real world Vmca is significantly higher ... then you are in the middle of it all. Perhaps you are putting far too much of your trust in the "guaranteed" transference of the artificial world of certification into the real dirty world of day to day operations ?

if you mis-handle the departure, maybe, but that isn't what we are talking about.

well, actually, we are .. that's one of the scenarios I am discussing

inertia is more of a factor in heavies

I don't think so .. just changes the numbers ..

GA twins are far more marginal than most transport-category turboprops.

not at all .. make the numbers appropriate and you can have just as miserable day in a heavy as on a puddlejumper

It does take a little while for an engine to run down

I'm glad we seem to be getting to an agreed position ..

the core has inertia

the fan is the main problem ..

that doesn't mean that it is producing any meaningful thrust.

have to disagree there .. during the rundown the thrust starts high and progressively runs down to whatever drag pertains to a failed engine

Remove the fuel, and you remove most of the energy

to cite a somewhat silly analogy .. consider a motor car .. the driver turns off the engine (no fuel flow now). You are standing in the middle of the road 50 odd metres away in the path of the car ... outcome ? I think I'd opt for exiting stage left pronto ?

as soon as the rate of increase of velocity peaks, you have deceleration (by definition)

depending on your frame of reference .. we are more concerned about earth based frames of reference, I suggest.

You simply can't have an acceleration if thrust is reduced below that necessary to counter drag

that sounds about right to a simple minded engineer like me

most of what you are seeing as a speed increase is actually instrument error

don't think so

I would love to see some hard facts on that whole subject

the following link

http://img.photobucket.com/albums/v318/john_tullamarine/Album%20001/speedoverrun.jpg

is to a scan of a page from the Boeing Performance Engineers Training Manual. Cursory review infers the failed engine progressive thrust rundown following Vef.

Similar pictures abound in the literature and reflect physical reality .. unless you are postulating infinite forces coming into play at the time the engine fails ...

There will be a little residual thrust, but most of it is being absorbed by the rotating mass of the engine (Newton's Third Law again).

we probably might be interested in having your expanded discussion on this point ?

Whatever thrust there is, is highly unlikely to be enough to counter drag and inertia sufficiently to produce a significant speed increase.

the numbers will vary across different Types .. Centaurus' figures reflect my recollections of the 737 ..

Think about it - if you launched down the runway at say, 25% thrust, would you ever get to V1? Probably not

I think I'd agree with that .. but the analogy essentially is irrelevant to the discussion

This is how the aircraft is certified

I would recommend a read of AC 25-7A first

I recognise that EFATO drills in a GA twin have a high risk factor.

lots of risks for heavy iron as well .. however, that statement is the start of doing some sensible risk assessment and mitigation when it comes to in-aircraft local proficiency training sessions ..

Vmca demos should and are demonstrated at a safe height

where they cease to be valid (other than for generic training value) and expose the aircraft to the risks of stalling and spinning ... for the life of me I can see little reason for Vmca sandpit playing beyond the initial multiengine endorsement .. and, even then, why not just stay away from Vmca ? A sensible quasi demo (not of Vmca but something approaching the sort of problems relevant to a static Vmca departure) at a sensible height has some validity for reinforcing the briefing but, even then, is of questionable value

it was not necessary to increase thrust during a simulated engine out T/O

or even a real failure .. and, then, be very wary of simply shoving the throttles up .. lest you be caught out with a thrust overshoot and the potential for a yaw departure if at min weight and min speed schedule. I can recall at least one fatal where this was postulated at the time (by me, as it happened) as a contributory cause.

the F27 would never be certified if it was introduced as a new type

the same can be said for just about any dated Type ..

it leaves the shaft because

.. of aerodynamic forces associated with its motion and, subsequently, gyroscopic precession once it is launched into independent flight ... never a nice thing to contemplate ...

when there is absolutely no power being applied to it

thrust is the key, not power ... one uses power to end up producing thrust.

you have invented perpetual motion

I have a suspicion that you really might need to revisit a dissertation on perpetual motion ?


I'm not really trying to be overtly difficult and a PITA here .. but the reality is that we spend most of our training time in comparatively benign areas of the operating envelope ... any fool/monkey can handle an overspeed takeoff failure at V1 .. in my view, ALL pilots should be exposed to the edge of this particular area of the envelope if for no other reason than to engender a very healthy respect for how hard an aircraft can bite if it's not treated with the healthy respect it demands ...

[Chimbu chuckles]

However, if you take an earth based reference, there is a progressive reduction in acceleration (during which the aircraft is still increasing its speed relative to the reference frame) eventually ending in a deceleration and the speed reduces .. is this not really a vital consideration for the discussion ?

I sit in awe - I wish I had the ability to word it as well:ok:

[john_tullamarine]

.. a wee glass of Amarula, followed by one of Wyanga Port .. or the other way around if that's what it takes to float your boat ... and one's literary success is assured .... both fine drops, if I may so say myself... only problem is that the former was far cheaper in RSA than it is in Oz ... memories of fine days gone by ..

.. at least, in the written word, one can go slowly enough not to get excessively tongue-tied and tripped up.

[remoak]

OK well it may be as well to leave the discussion on acceleration to one side, as it isn't entirely relevant and in any case, depends on the framework you are using. I was looking at it from a purely physics-based viewpoint (rate of change of velocity), you seem to be looking at it from a purely mechanical standpoint (ie change of velocity). So unless you want to explore it further, I suggest we put that one away for now.

[edit... on second thoughts...]

if we take the failure point acceleration as reference then, of course, there is a subsequent deceleration. However, if you take an earth based reference, there is a progressive reduction in acceleration (during which the aircraft is still increasing its speed relative to the reference frame) eventually ending in a deceleration and the speed reduces .. is this not really a vital consideration for the discussion ?We may (possibly) be talking about two different things. There is obviously an increase in speed (and acceleration) from the failure point to the recognition point... however, as soon as you close/retard the thrust levers, you have removed the source of energy that is used to produce thrust. Now what I am waiting for you to explain to me, is how an object, being acted upon by a tiny amount of thrust and a whole heap of drag, can continue to increase it's speed, other than for a fraction of a second? Irrespective of how you define acceleration, there is simply no way that an object that is subject to an overwhelming retarding force (drag) and virtually no thrust, can do so. Please explain how that is possible. It is like saying that if you accelerate to 100km/h in your car and then take your foot off the throttle, the car continues to increase speed. it simply doesn't - inertia cannot produce a positive acceleration. By all means prove me wrong, I am hanging out for an explanation! Even your graph agrees with me.

Unless, of course, we are using different definitions of acceleration... that might explain the confusion. I am using the standard physics definition (rate of change of velocity).

perhaps you might list the variety of reasons (for airspeed errors) to which you refer ?Fixed and variable position error, hysteresis, software error in EFIS systems, sometimes ADC-related errors, for example incorrect temperature inputs where the temp probe has been sitting in direct sunlight.

Reality on the line is quite different and startle factor has to be contended with .. it is for this sort of consideration that A/L 42 was introducedHmmm well we always trained our guys to assume that they would have a failure and be ready, and in all my years conducting line checks I never found anyone not taking that seriously... although it is obviously possible. Not familiar with A/L 42, is that an Aussie thing?

For the next 20 or so points, it seems to me that we are seeing a different philosophy in both training and operation between the JAA system (with which I am familiar) and the Australian system (which you are familiar with). I spent a lot of hours in the F27 sim trying to get it to depart from controlled flight on departure, because that was a training emphasis that we had a after the Prestwick J32 accident. In many hours of experimentation, we came to the conclusion that you would have to seriously mis-handle the departure to get into the sort of trouble you are describing. Part of that may be that we opted to round our speeds up a few knots, and make everything generally safer, even if it did cost us a few kilos on marginal runways. So, for example, our low-weight speeds would always be a few knots higher than strictly necessary to enhance safety. What is the point of performing a low-weight takeoff at minimum speeds? There isn't one, so why do it?

Sure, if you have already departed in yaw there is not much you can do to save the day, but our training concentrated on never getting into that position in the first place. We used speeds that simply didn't put you in the position where Vmca/Vmcg could be limiting.

All your examples seem to be predicated on gross mis-handling at low weights and minimum speeds... and while that is certainly possible, no prudent operator is going to operate the aircraft that way, nor train that way. Firstly, because it isn't sensible, and secondly, because it isn't necessary. You can kill yourself in an aircraft in a variety of ways, and you simply can't legislate for all of them... but if you operate it sensibly and with a little airmanship, there is no reason for that to happen.

Anyway, back to answering your points...

now, I had three years of great fun on the Friendly .. but it, the same as most other aircraft, WON'T accelerate through the problem area if, for whatever reason, the aircraft has already departed in yaw ... keep thrust on and you just wind yourself into a tighter ball in the weeds ...But surely the point is that, if you fly it correctly, you WON'T depart in yaw in the first place?

as before, for a min weight, min speed schedule .. if the real world Vmca is significantly higher ... then you are in the middle of it all. Perhaps you are putting far too much of your trust in the "guaranteed" transference of the artificial world of certification into the real dirty world of day to day operations ?...or maybe certification in Australia is different to certification in Europe... dunno.

My understanding of Euro certification process is that it takes account of all adverse factors to a level that can be expected 90% of the time (to put it really, really simply... I don't particularly want to start quoting broad swathes of EASA manuals). Maybe it is different in Oz - how about you give us a real-world example of how you can get into the min speed schedule/Vmca/Vmcg problems you are suggesting?

inertia is more of a factor in heavies

I don't think so .. just changes the numbers ..From memory, inertia is proportional to mass... might be wrong though.

GA twins are far more marginal than most transport-category turboprops.

not at all .. make the numbers appropriate and you can have just as miserable day in a heavy as on a puddlejumper
Maybe, but the certification requirements are different... I doubt the performance reserves of a Navajo would be considered adequate for a 737 (proportionally of course).

to cite a somewhat silly analogy .. consider a motor car .. the driver turns off the engine (no fuel flow now). You are standing in the middle of the road 50 odd metres away in the path of the car ... outcome ? I think I'd opt for exiting stage left pronto ?That has nothing to do with acceleration, and everything to do with momentum and inertia. The car isn't accelerating towards you, it is slowing down (ie accelerating in the other direction).

as soon as the rate of increase of velocity peaks, you have deceleration (by definition)

depending on your frame of reference .. we are more concerned about earth based frames of reference, I suggest.The frame of reference is a simple kinematic one... about as earth-based as you can get.

scan of a page from the Boeing Performance Engineers Training Manual. Cursory review infers the failed engine progressive thrust rundown following Vef.What that graph shows is a continued acceleration from the point of failure to the point of recognition of the failure, at which point acceleration peaks... and then reduces. If we assume the point of recognition is slightly before the point at which the thrust levers are retarded (which it always will be), it is clear that from that point onwards, acceleration is decreasing. In other words, there is no evidence at all from that graph that speed increases past the point of recognition.

There will be a little residual thrust, but most of it is being absorbed by the rotating mass of the engine (Newton's Third Law again).

we probably might be interested in having your expanded discussion on this point ?Sure. It takes energy to rotate the engine... most of the ground idle fuel flow is dedicated to simply keeping the turbine rotating at around 50% to ensure a self-sustaining cycle. There is very little actual thrust being produced. maybe I worded it badly... how about "there is very little residual thrust, as most of the energy required to produce thrust is being absorbed by the rotating mass of the engine".

Think about it - if you launched down the runway at say, 25% thrust, would you ever get to V1? Probably not

I think I'd agree with that .. but the analogy essentially is irrelevant to the discussion
Yeah but the rest of that paragraph is very relevant:

"Think about it - if you launched down the runway at say, 25% thrust, would you ever get to V1? Probably not... and an idling engine is probably producing no more than 10% thrust. There is no way that an engine that is only receiving enough fuel to produce 10% thrust, is going to accelerate the aircraft it is bolted to at anywhere near the levels of drag it will be experiencing near V1."

it leaves the shaft because

.. of aerodynamic forces associated with its motion and, subsequently, gyroscopic precession once it is launched into independent flight ... never a nice thing to contemplate ...And the the "aerodynamic forces associated with it's motion" come from where? That's right... inertia. Which is what I think I said.

thrust is the key, not power ... one uses power to end up producing thrust.Power + propeller = thrust...

I'm not really trying to be overtly difficult and a PITA here .. Could have fooled me... ;)

but the reality is that we spend most of our training time in comparatively benign areas of the operating envelope ... any fool/monkey can handle an overspeed takeoff failure at V1 .. in my view, ALL pilots should be exposed to the edge of this particular area of the envelope if for no other reason than to engender a very healthy respect for how hard an aircraft can bite if it's not treated with the healthy respect it demands ... Sure... but ONLY in the sim, or at a safe altitude. Nobody is against exploring the dark corners of an aircraft's performance envelope, in fact most of us enjoy it... well, I do, anyway.

But better yet... operate the aircraft in such a way that a pilot never needs to even come close to finding out the limits the hard way... prevention being always better than the cure...

[john_tullamarine]

Now what I am waiting for you to explain to me, is how an object, being acted upon by a tiny amount of thrust and a whole heap of drag, can continue to increase it's speed

I don't know what sort of aircraft your experience is on .. the reality is that, especially for high bypass fans, you cannot cause the thrust to disappear instantly. The engine runs down .. and it just can't stop producing thrust. The rundown is faster in the case of a failure compared to a throttle chop but nonetheless associated with a very observable and finite time delay.

If you don't accept that, that's fine .. but your reticence doesn't change the real world fact of engine rundown ...

During the rundown period, the thrust progressively reduces, resulting in a speed overrun with a hump such as shown generically in the Boeing sketch. Just the way the real world works, I'm afraid.

By the time that the rundown has finished, or nearly so, the residual thrust is either low/negative and your statement is quite correct. However, it is during the intervening period of rundown where the thrust is comparatively high and this results in the speed overrun.

It is like saying that if you accelerate to 100km/h in your car and then take your foot off the throttle

then let's follow your analogy .. while you are taking your foot off the throttle, the car WILL continue to accelerate with the characteristics relating to the vehicle's mass and the engine rundown characteristic. At some point during that foot movement (rundown), the engine power (think thrust line at the driving tyres) will reduce to a point where the net acceleration is negative (deceleration) and the speed trend reverses with the car starting to slow down .. is this not pretty well exactly what happens in the aircraft .. replacing foot movement by a throttle chop ? The only difference of note is that the rundown characteristics for throttle chop and failure vary with the latter being somewhat more rapid .. but you still get significant thrust in the intial stages of that rundown while the fan slows down. Keep in mind that the blades don't know whether they are being driven by the hot end or are just slowing down .. so long as the air is coming over the blades then we have the production of lift forces resulting in thrust for a measurable time interval.

inertia cannot produce a positive acceleration

.. but continued (slowing) motion consequent to inertial effects certainly can continue to produce forces which can produce such acceleration ... for a period.

Even your graph agrees with me

I don't think so .. perhaps you might expand on this suggestion ?

Unless, of course, we are using different definitions of acceleration

we are quite consistent .. I suggest that your confusion arises from different frames of reference. The end result is the same for the aircraft .. with a speed increase for a bit coming over the hump ...

Fixed and variable position error, hysteresis, software error in EFIS systems, sometimes ADC-related errors, for example incorrect temperature inputs where the temp probe has been sitting in direct sunlight.

.. and these only become significant when you suffer an engine failure during the takeoff ? I don't really think so.

Indeed, how do you show any causal relationship between an engine failure and such errors ?

In any case, the altimeter accuracy requirements, via the static interconnection, result in typical maximum ASI errors of, say, 4-5kt ... all rather independent, however, of engine failure.

Not familiar with A/L 42, is that an Aussie thing?

The FAR amendment which introduced the accel-stop 2 second delay. If you go back far enough in the local Industry, you will recall the equivalent Oz ANO 101.6 A/L 62 which introduced the parallel Oz requirement.

I spent a lot of hours in the F27 sim trying to get it to depart from controlled flight

that's because the sim does not replicate the dynamics outside the programmed (tested) envelope. If you have been a bit slower, and depending on the fidelity characteristics, you may/may not have seen something representative. As you would be aware, sims are computers, not aeroplanes, and the fidelity only is reasonable in the flight test validated envelope (for the sim). For example, I used to play in a 732 sim pre- and post- the FAA mandated mod to introduce the updated rudder model. Pre-mod the low speed characteristics were a bit of joke and not even of much use for generic training .. post-mod it was a whole new tiger. Similar considerations apply to whatever F27 sim you cite ie you were trying to get a confused computer to depart .. not the aircraft.

Part of that may be that we opted to round our speeds up a few knots

.. now, why ever would you have thought to do such a thing ? :}

What is the point of performing a low-weight takeoff at minimum speeds?

.. generally because the runway is so length critical .. and you want those last few kilos. The more important consideration is that the AFM data is based on idealised circumstances ... if you don't replicate that ideal .. then you can get bitten very badly in this area of the operating envelope .. this is main thrust of the discussion as most pilots have very little understanding of how things work in this (not often played in) sandpit .. which is why old pharts like me and Old Smokey (Mutt and MFS are not quite as decrepit as we are yet but they're working on it) continue to harp on such matters.

Sure, if you have already departed in yaw

thank heavens .. at last ... congruent thought.

there is not much you can do to save the day

Actually you can reduce thrust by bringing the throttles back a bit and, for Vmca, push the nose down to accelerate/crank in a bit more bank .. but you have the main idea ... once you depart, you lose all the other nice things and you either die or do something a bit non-SOP in a valiant attempt to avoid death.

but our training concentrated on never getting into that position in the first place

and more strength to you and your fine attitude, good sir.

We used speeds that simply didn't put you in the position where Vmca/Vmcg could be limiting

fine if you are well above book speeds. The concern in question is real world effects if you are somewhere near book speeds.

All your examples seem to be predicated on gross mis-handling at low weights and minimum speeds

that's only one precedent scenario .. the others are just as important - crosswind, systems failures, etc. Doesn't really matter what sets up the critical scenario. Captain Speaking still has to do sometime at the time to try to resurrect the situation ..

but if you operate it sensibly and with a little airmanship, there is no reason for that to happen.

in the low speed end of the envelope, there is a perceived lack of knowledge amongst the piloting fraternity. The value of this sort of discussion is that some of the problems (which are not generally well understood) are tossed around for the potential learning benefit.

Operating sensibly is fine ... if the aeroplane and the ambient conditions approximate the book story.

if you fly it correctly, you WON'T depart in yaw in the first place?

that is a good starting point .. providing that the other gremlins don't come out and bite you.

or maybe certification in Australia is different to certification in Europe... dunno

the basics of certification are reasonably well harmonised amongst the various Authorities. However, you appear, quite steadfastly, to be rejecting the proposition that the certification is an idealised version of the real world and, if the real world doesn't approximate the ideal .. then you can get bitten and bitten hard.

to a level that can be expected 90% of the time

I don't know that that's a valid proposition .. the basis is on a measure of statistical risk but the concept is similar. I suggest that the certification idealisation gets it reasonably applicable to a far more higher level than you are suggesting ... the concern in the discussion has been the low probability situation which overwhelms the pilot and arrives on Page 1 of the tabloids that evening ..

how about you give us a real-world example of how you can get into the min speed schedule/Vmca/Vmcg problems you are suggesting?

too easy ...

(a) significant adverse crosswind for Vmcg

(b) banking the wrong way for Vmca

(c) systems failures causing higher than certification yaw couples for both

etc...

From memory, inertia is proportional to mass

that's close enough ... the point is that inertia affects any machinery ... the numbers will depend on the specifics.

I doubt the performance reserves of a Navajo would be considered adequate for a 737

of course not .. perhaps my earlier comment was a bit too flippant ?

That has nothing to do with acceleration, and everything to do with momentum and inertia.

my point has been, and perhaps I have been unsuccessful in trying to get it across, we are not overly concerned about acceleration but more about the forces which might follow consequent to the effects of mass and motion ...

The frame of reference is a simple kinematic one... about as earth-based as you can get.

as I am not an expert in the discipline of mechanics I think we probably will just agree to disagree on minor semantics ? However, from an earth based frame aircraft speed continues to increase in the period immediately following the failure due to rundown charateristics ... only for a short period, agreed, but it is a real effect and affects distances etc.

there is no evidence at all from that graph that speed increases past the point of recognition.

the curve shapes to me tell a different story .. best we just agree to disagree. The discussion related to the rundown characteristics .. so the section of interest is post failure rather than post recognition ?

maybe I worded it badly

that's fine .. once the rundown has completed its sequence and you are back at idle (or failed, as the case may be)

the rest of that paragraph is very relevant

not really .. the discussion point centres around the thrust variation during rundown, not the steady state.

That's right... inertia. Which is what I think I said.

the inertia results in the motion .. which is the driver for the forces ... pedantic point with which we probably will go nowhere ...

Nobody is against exploring the dark corners of an aircraft's performance envelope, in fact most of us enjoy it... well, I do, anyway

we are in heated agreement when it comes to training .. far too much training risk has converted into prangs over the years ... the concern is the real world situation when, for reasons often outside the pilot's control, he/she is thrust into a situation which is outside the idealised certification world

But better yet... operate the aircraft in such a way that a pilot never needs to even come close to finding out the limits the hard way... prevention being always better than the cure...

I think this statement highlights our differing points of view .. you are taking the position that, by adherence to AFM procedures and SOP, you are ironclad. That applies MOST of the time but not ALL of the time. Historical reality shows that numerous accidents result from a disjoint between the ideal worlds of certification and SOP and the dirty, unfair, real world.

We should have a beer sometime to discuss philosophy ....

[remoak]

you cannot cause the thrust to disappear instantly. The engine runs down .. and it just can't stop producing thrust. The rundown is faster in the case of a failure compared to a throttle chop but nonetheless associated with a very observable and finite time delay. OK... I see the problem. We are indeed talking about two different things.

I am talking about acceleration as defined in kinematics and physics...

"Acceleration is the rate of change of velocity as a function of time. It is vector. In calculus terms, acceleration is the second derivative of position with respect to time or, alternately, the first derivative of the velocity with respect to time".

You are talking about acceleration as it is commonly used ie "an increase in speed".

What you don't seem to be able to see is that when you close the thrust levers, the speed may increase slightly (which I am not in disagreement with you about), but the acceleration (remember: the RATE of CHANGE of velocity) is negative.

We should probably be more careful with our use of the terms "speed" and "acceleration".

the car WILL continue to accelerate with the characteristics relating to the vehicle's mass and the engine rundown characteristic.No... it won't. The RATE of change of velocity will immediately reduce (in fact it will become negative with respect to the forward motion of the car). You are confusing change of velocity with rate of change of velocity.

.. but continued (slowing) motion consequent to inertial effects certainly can continue to produce forces which can produce such acceleration ... for a period.Yes but the acceleration is negative (ie a deceleration in common parlance).

Even your graph agrees with me

I don't think so .. perhaps you might expand on this suggestion ?
Again, you seem to be confusing speed and acceleration. Your graph (certainly to my eyes, although it is a little fuzzy) shows that the acceleration (the rate of change of velocity) peaks fractionally after the recognition of failure, and then decreases. Given that there is small time delay between recognition and action (around 7/10 of a second), the graph shows that acceleration (not necessarily speed) peaks at the point where the thrust levers would be retarded, and then decreases. That peak represents the point where the rate of change of velocity is zero... not the point where the change of velocity is zero. Maybe you are seeing something different...

Fixed and variable position error, hysteresis, software error in EFIS systems, sometimes ADC-related errors, for example incorrect temperature inputs where the temp probe has been sitting in direct sunlight.

.. and these only become significant when you suffer an engine failure during the takeoff ? I don't really think so.

No, but they are significant at any time that you are in the speed range up to V1, and position errors can become significant when there is either a significant crosswind, or yaw (either of which can result in disturbed flow over the static ports).

Indeed, how do you show any causal relationship between an engine failure and such errors ?Yaw.

The FAR amendment which introduced the accel-stop 2 second delay. If you go back far enough in the local Industry, you will recall the equivalent Oz ANO 101.6 A/L 62 which introduced the parallel Oz requirement.
Ah OK. Not familiar with Aussie regs (and have no desire to study them!)

Similar considerations apply to whatever F27 sim you cite ie you were trying to get a confused computer to depart .. not the aircraft.Yeah no not really. I'm not sure if you are familiar with simulator certification, but one of the requirements is that the simulator replicate the observed, real-world physical characteristics of the aircraft, as derived from real-world, analogue (in the case of the F27) flight test data. The computer is in no way confused; it is reacting according to the baseline data that it references depending on the phase of flight, which is itself real-world data gathered during actual flight testing. From memory, the level of fidelity (tested yearly for certification) required for the F27 was 2%.

However, you appear, quite steadfastly, to be rejecting the proposition that the certification is an idealised version of the real world and, if the real world doesn't approximate the ideal .. then you can get bitten and bitten hard.Certification is based on real-world data (which is the whole point of flight testing). It cannot be exhaustive, but neither is it quite the contrived, anodyne data set that you seem to think it is. Once it has been padded out with all manner of allowances and safety factors, it works fine for 99.5% of conceivable circumstances.

The "real world" has to get a pretty long way from the real world on which certification is based to "bite you hard". That is why there are (statistically) so few accidents.

too easy ...I meant with numbers... :ugh::}

the point is that inertia affects any machinery ... the numbers will depend on the specifics.... and it affects machinery with a higher mass proportionally more, was my point.

perhaps my earlier comment was a bit too flippant ?Nah... surely not... :)

we are in heated agreement when it comes to training .. far too much training risk has converted into prangs over the years ... the concern is the real world situation when, for reasons often outside the pilot's control, he/she is thrust into a situation which is outside the idealised certification worldI think the problem is that, as it may turn out to be in this accident, it is likely that the circumstances of an accident flight never stray outside the certification envelope - and yet the accident still happens due to shortcomings in the wetware...

you are taking the position that, by adherence to AFM procedures and SOP, you are ironclad. That applies MOST of the time but not ALL of the time. Historical reality shows that numerous accidents result from a disjoint between the ideal worlds of certification and SOP and the dirty, unfair, real world. No, I'm taking the same position you are. My contention is simply that when you see accidents like the one we are discussing, the problem is not that the aircraft departs due to a confluence of factors outside the control of the pilot - rather, the pilot(s) get themselves into a situation that is unrecoverable. The difference is that the fault lies not in the certification process - which, although undeniably flawed, is the best process that can reasonably be used; it lies in the way the equipment is operated.

If you are an experienced pilot, and choose to go to the places where dragons live, you shouldn't be surprised if you eventually get singed by their breath.

You seem to be saying that aircraft can quickly kill you and that it is the fault of certification for not adequately protecting you; I am saying that the process is as good as it can reasonably be, and that pilots are required to exercise judgement and airmanship.

Putting that into the context of this accident, I'm more than happy to stick my neck out and say that it will turn out to be an unnecessary and easily preventable accident, because the history of training accidents is full of similar examples.

We should have a beer sometime to discuss philosophy .... Yep that would indeed by a great use of an evening or two... :ok:

[flighthappens]

mmmm physics... Remoak sorry mate I disagree..

What you don't seem to be able to see is that when you close the thrust levers, the speed may increase slightly (which I am not in disagreement with you about), but the acceleration (remember: the RATE of CHANGE of velocity) is negative.

Remember that the derivative of a graph at any point is the slope of the line, and that acceleration is the derivative of velocity (which in itself is the derivative of position). Thus if at any time the speed (velocity) is increasing, the aircraft is accelerating. When that speed (velocity) reaches its peak, the acceleration is instantaneously zero. As the speed (velocity) starts to deccelerate the aircraft is now deccelerating or has negative acceleration.

To put it even simpler, accelerating to a steady state there will never be negative acceleration, as you can see below...

http://www.lightandmatter.com/html_books/1np/ch03/figs/sample-xva-graphs.png

[remoak]

Thus if at any time the speed (velocity) is increasing, the aircraft is accelerating.

Not in physics it isn't.

Acceleration being a measure the rate of change of velocity, not the change of velocity.

So if we graph speed against time, and have say the following values...

1 sec/10kts, 2 secs/20kts, 3 secs/30 kts, 4 secs 40kts -

...we can say that the change of velocity is 10kts/sec, and the rate of change of velocity is also 10kts/sec.

But if the figures change to, say -

1 sec/10kts, 2 secs/20kts, 3 secs/25 kts, 4 secs 28kts -

... the velocity is still increasing, but the rate of change of velocity is decreasing, which amounts to an acceleration in the opposite direction, or a deceleration relative to the velocity vector.

As the speed (velocity) starts to deccelerate the aircraft is now deccelerating or has negative acceleration.

No, for the reason above (but in the opposite sense). So, for example, if the speeds become -

1 sec/50kts, 2 sec/40kts, 3 sec/30kts, 4 secs/20kts -

... we have a change of velocity and rate of change of velocity of 10kts/sec. Now if those figures become -

1 sec/50kts, 2 sec/40kts, 3 sec/45kts, 4 secs/42kts -

... the velocity is still decreasing, but so is the rate of change of velocity - in other words, an acceleration in the original direction of travel, or, if you like, a negative deceleration.

To put it even simpler, accelerating to a steady state there will never be negative acceleration, as you can see below...

The diagram doesn't fully illustrate the problem, as velocity is a vector quantity. In order for the velocity to decrease, you actually have (at least) two vectors, one acting in the direction of travel, the other acting in the opposite direction. The graph merely shows one aspect of what is happening. Acceleration doesn't have to go below the line to be a negative acceleration. Otherwise, the implication is that, in that example, the rate at which velocity is increasing is itself always increasing by an incrementally smaller amount - which it clearly isn't.

[First_Principal]

A cr*pload of nasty maths 'n graphs 'n stuff about what comprises acceleration

I'm with Remoak on this, in my view it's much the same as big E's theory of relativity - bearing in mind what's relative to the observer.

The analogy and thesis to me is thus: observer and airplane are increasing in speed almost together (travelling in the same direction) but the 'plane is creeping ahead of the observer (ie. it's accelerating away from the obsserver because it's rate of change of speed is greater than the observers, relative also to a third - fixed - observer say). If you cut the throttles that 'plane relative to observer one will begin to get closer (ie. the rate of change will become negative relative to that observer) and the observer will now catch up and rapidly pass the 'plane. But the increase in speed relative to observer two for the 'plane [and obs 1] may continue for a time - albeit the rate of change (read: acceleration) is immediately affected.

I'm not sure if that muddies the water or clears it - or if I've managed to make a total arse of myself :\ - but all this other stuff was beginning to hurt my head and I just had to try and simplify it for myself...

Cheers, P.

[flighthappens]

Not in physics it isn't.What, physics and mathematical laws dont tie into each other anymore?

Acceleration being a measure the rate of change of velocity, not the change of velocity. Acceleration is the rate of change of velocity with respect to time, yes. Also known as a = dv/dt.

... the velocity is still increasing, but the rate of change of velocity is decreasing, exactly - rate of change of velocity is decreasing (from 10m/s/s to 5m/s/s to 3m/s/s) - however it remains a postive (+10,+5, +3)

which amounts to an acceleration in the opposite direction, or a deceleration relative to the velocity vector. No it does not. The velocity vector is still increasing (unless 25 is greater than 28?)....The rate of change of acceleration in this example (jerk - yes that is the unit name) is a negative quantity

alternatively can you please explain how it is possible to accelerate an object as you are proposing (i.e. its average rate of change of velocity with respect to time from t3 to t4 is 3/m/s^2) with an acceleration (which implies a net force) in the opposite direction...

Acceleration, velocity, and Position (http://www.ugrad.math.ubc.ca/coursedoc/math101/notes/applications/velocity.html)
Jerks - Third derivative of position (http://www.phys.ncku.edu.tw/mirrors/physicsfaq/General/jerk.html)

Anyway, to paraphase Forrest Gump, "im sorry for ruining your thread"...

[Pinky the pilot]

to paraphase Forrest Gump, "im sorry for ruining your thread"...

If I may paraphrase Vinnie Barbarino in 'Welcome back Kotter'....
'I'm so confused!!':uhoh:

With all due respect Gentlemen, I lost it a couple of pages back.:{
The digression of this thread into what seems to me to be somewhere near a third year, University level applied Physics course has me totally confused.

Whilst the last few posts may be correct in Physics and applied Maths, may I suggest that the actual relevance to the thread title is somewhat tenuous!

Or if I may be blunt; I don't give a rats anal passage when acceleration actually ceases once power is pulled from an enigine or engines. All I really want from this thread is anything which may assist me in ensuring that I avoid the same unfortunate outcome from this tragic event!

With apologies where necessary.

[werbil]

I'm with flighthappens and jt on this one.

QUOTE]Acceleration is the rate of change of velocity as a function of time. It is vector. In calculus terms, acceleration is the second derivative of position with respect to time or, alternately, the first derivative of the velocity with respect to time[/QUOTE]

Remoak IMHO you are confusing the third derivative of position (rate of change of acceleration) with the second (acceleration).

lets take a model car with no internal propulsion on a flat surface, and to simplify the example all forces are assumed to be in the one direction and its reciprocal which for the purpose of the exercise will be north/south.

For the first second I apply a constant force towards the north by it by hand so that it accelerates from stationery to 1 m/s north.
For the second second I apply a constant force towards the north so that it accelerates from 1 m/s north to 3 m/s north.
For the third second I apply a constant force towards the north so that it accelerates from 3m/s north to 4 m/s north.
For the fourth second I apply no force - there is no change in velocity and continues travel at 4 m/s north.
For the fifth second I apply a constant force towards the south (ie in the opposite direction) so that it decelerates from 4 m/s north to three m/s north.

In the first second the change in velocity is 1 m/s in one second therefore the rate of change in velocity is 1 m/s/s and the direction is to the north.
In the second second the change in velocity is 2 m/s in one second therefore the rate of change in velocity is 2 m/s/s and the direction is to the north.
In the third second the change in velocity is 1 m/s in one second therefore the rate of change in velocity is 1 m/s/s and the direction is to the north.
In the fourth second the change in velocity is 0 m/s in one second therefore the rate of change in velocity is 0 m/s/s and there is no direction.
In the fifth second the change in velocity is 1 m/s in one second therefore the rate of change in velocity is 1 m/s/s and the direction is to the south.

In my book in this example the deceleration begins to occur when the direction element of the rate of change of velocity occurs ie in this case when the speed of the body starts to reduce.

Anything else would result in free energy and momentum.

werbil

PS This thread is like the downwind turn discussion. Pinky is right about the relevance of the thread drift (I know, I know I am guilty of continuing it) and the real life affects are far more interesting. If I dare may I suggest I would have expected a moderator to try and get it back on track rather than getting fully involved.

[tail wheel]

Seriously, this debate is so far from the Brasilia accident, I'm inclined to close this thread and you Einsteins can open a new thread on the other forum, to debate calculus, Pythagorus and the Theory of Relativity? :confused:

Thread topic debate, or new topic in a new thread? :=

[yowieII]

Hear 2*1/2V2(2+2=)4 Hear:confused:

[john_tullamarine]

While this discussion may appear to be arcane :uhoh::uhoh:, even inane :bored::bored:, to some, hopefully a few interesting and potentially valuable bits rub off onto the new chums ...

You are talking about acceleration as it is commonly used ie "an increase in speed".

not at all .. my studies from an early exposure have used the same style of definition as you have cited ..

when you close the thrust levers, the speed may increase slightly

which is the important bit to the pilot's management of the overall problem ..

No... it won't. The RATE of change of velocity will immediately reduce

how about if I give up on this one ? .. it really doesn't have all that much practical significance to the piloting problems and we don't appear to be getting anywhere fast ..

you seem to be confusing speed and acceleration.

not at all .. however, I am interested in speed as that dictates the immediate performance and handling concerns .. the acceleration is of relevance to me if I am producing basic performance predictions or analysing aircraft motions .. but not from the point of view of driving the aeroplane ..

Maybe you are seeing something different...

no .. we are just concerned about different aspects of the thing

position errors can become significant when there is either a significant crosswind, or yaw

concur ... but the effects are sensibly minor

Not familiar with Aussie regs

the FAR amendment is the important consideration - the Oz reg change largely mirrored the US document - apologies .. for some reason I had it in mind that you were in Oz .. brain infarct, I guess.

I'm not sure if you are familiar with simulator certification

more than sufficient for Government work ..

the simulator replicate the observed, real-world physical characteristics of the aircraft

... until you come to extrapolating that same WT/FT data .. and that is what you are suggesting here .. depending on how the techs tweak the particular box, we can see reasonable fidelity within (at least some areas of) the test environment .. but sometimes the most dreadful extrapolation outside. I venture to speculate that your F27 sim will either be very dated or simple compared to the usual modern boxes ?

Certification is based on real-world data

absolutely .. and idealised real world data at that .. the concern under discussion is what do we do when the certification assumptions fail in the real world and the poor folk in row 0 have to come up with a fix .. real quick ?

Now, I have a reasonable engineering and flying background in certification so I am pretty comfortable with my views ..

it works fine for 99.5% of conceivable circumstances.

I would suggest very considerably more than such a figure .. but the point remains that it is not exhaustively comprehensive and that is what leads to the infrequent circumstances which, historically, have done a masterful job of biting pilots in anger

The "real world" has to get a pretty long way from the real world on which certification is based to "bite you hard".

not at all .. the several scenarios I cited can arise quite easily. I suggest that you may be confusing that with the normal margins from edge of the envelope problems which pertain to "normal' and "routine" operations

I meant with numbers...

the Vmcg crosswind deltas I cited come from OEM flight test and analytical data for particular aircraft - DC9 for the twin and, as I recall, 747 for the quad .. the former I am comfortable with as the relevant correspondence was directed to me .. the latter was secondhand. The other circumstances are going to be highly variable according to circumstances on the day.

it is likely that the circumstances of an accident flight never stray outside the certification envelope

most don't .. some certainly do. O'Hare and Sioux City spring to mind as obvious examples ... in the former, the crew did the "right" thing for the then present wisdom (which wisdom was changed after the investigation) and the latter had sufficient time to play with the problems to get a (rather minor) degree of predictable control. Indeed, had the phugoid not caught them out at the last moment and rolled them up into a ball .. they just might have got away with acquiring God-like status amongst the wider set of colleagues ..

There are plenty of other examples in the history of the game .. overall, a small set of instances, I grant you .. but it does happen and it helps if pilots have a basic idea of what lies behind the certification processes.

The good ATSB folk will, no doubt, dig and sift out the specifics of the -120 story over the next few months or so.

My contention is simply that when you see accidents like the one we are discussing, the problem is not that the aircraft departs due to a confluence of factors outside the control of the pilot - rather, the pilot(s) get themselves into a situation that is unrecoverable.

your perception is rather more confident than mine in respect of the specific mishap.

The investigation may find in one direction or the other .. or, indeed, in both ...

I have some information from a well-placed source that causes me to speculate whether we may well find out in due course that there were both systemic and systems causal problems and, indeed, the pilots may well have just been caught out, did the best they were able on the day ... but the aircraft won that particular battle ..

I am very confident that my ATSB colleagues will dig out the details of the story .. one way or the other. However, it remains preferable that we minimise specific speculation on this mishap .. if for no other reason than that it will cause needless hurt to the families left behind.

the fault lies not in the certification process ... it lies in the way the equipment is operated.

we are quite misaligned on this one. My work history convinces me that, on many occasions, systems and environmental problems do come into definitive play. Certainly, the environmental problems overlap the SOP arena but then we get into state of knowledge and training issues etc .. I prefer the view that the operational side of things can either help or hinder a particular emergency situation for all the usual reasons.

If you are an experienced pilot, and choose to go to the places where dragons live, you shouldn't be surprised if you eventually get singed by their breath.

I concur with that view .. although I don't usually cite names, "Bud" Holland comes to mind as a salient and unfortunate example ..

However, my concern is not with operational arrogance or culpable behaviour (and I have absolutely no reason to suspect that the present mishap crew was other than disciplined and appropriate in their flying generally and their actions on the day).

Although you appear to be uncomfortable with the idea, reality is that crews do occasionally find themselves in a very difficult place, unexpectedly, and through no particular professional fault of their own.

You seem to be saying that aircraft can quickly kill you

indeed they can, and do .. the main difference between one prang and another being the newsworthiness ..

and that it is the fault of certification for not adequately protecting you

not at all ... my background over the years generally was in certification areas and I have no philosophical difficulties with the way the processes work and the Standards evolve.

The problem is that the design standards and the certification processes are NOT exhaustive and do NOT cover all eventualities .. indeed, no-one who is reasonable would suggest that they do or will .. simply on the basis that the system is driven by probabilities not guarantees. That is to say, when we go to work in this Industry, we have a pretty good chance of going home at the end of the day .. but not a guarantee.

My interest is to see pilots understand and appreciate that point .. and manage their operations with due consideration to the practical boundaries of the certification processes.

pilots are required to exercise judgement and airmanship.

concur .. but there is a disjoint in that the typical pilot does not have an adequate knowledge of the background stuff so he/she can be at a bit of a disadvantage when it comes to exercising sound decision making skills when technical problems out of the ordinary arise.

Indeed, many of us olde pharts opine that the situation in that regard progressively worsens as the design complexity increases and the bean counters take ownership ...

I'm more than happy to stick my neck out and say that it will turn out to be an unnecessary and easily preventable accident

perhaps .. but, at this stage, I won't be surprised to see one of a number of possible systems problems be implicated and, perhaps, some related systemic considerations. Certainly none of us will know much in the way of a specific or concrete story until the ATSB has done its work.

because the history of training accidents is full of similar examples.

true .. but that impinges on statistics and statistics doesn't address what the next sample outcome will be discretely .. it only gives an educated prediction of what that outcome probably will be .. and therein lies the flaw in your logic, I suggest

Yep that would indeed by a great use of an evening or two... http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/thumbs.gif

.. and if we can entice OS et al to join us .. that would be an understatement.


with your last post, I'm afraid that you're talking mechanics nonsense, old son ...

observer and airplane are increasing in speed almost together (travelling in the same direction) but the 'plane is creeping ahead of the observer

God only knows what frame of reference you have adopted ?

The digression of this thread into what seems to me to be somewhere near a third year

actually more around the level of mid-secondary algebra and beginner level differential calculus.

Actually, folk, the acceleration nonsense is not of any great relevance to anything in the piloting side of things ... perhaps we can leave it be.


Seriously, this debate is so far from the Brasilia accident

hopefully, Remoak will drop his obsession with accelerating irrelevancies and we can, indeed, get back to what pilots are interested in .. and things which are relevant to piloting ?

[xxgoldxx]

yep... we are in the industry to attract rocket scientists...
is that not why we have speed bugs etc...?
there is no time to discuss the relevant points of modern astrophysics...

[RENURPP]

Guys, JT Remoak etc, no one minds if you want to continue discussing this stuff, its very exciting :sad: but do it some where else.

If the next thread you start or have an interest in is taken over to discuss the ancient history of Rome, I suspect you might have something to say.

Now you have proven you completed maths and physics at school so be good boys and obey the teacher and go and play somewhere else. How about the school library?

Bye

JT is supect the others are just like you, have to have the last say.

[frigatebird]

Whew..!
Was going to say my head was hurting a page or so ago..
Appreciated J-T's #308 summing up tho..
Thanks to all posters for continuing an education, and with the deepest respect to those with loss in these tragic circumstances.

[RENURPP]

Sure keep it up, start a new thread titled " The Physics of Acceleration".

[F.Nose]

Whilst I agree that an in depth analysis of the physical properties of inertia, momentum and acceleration etc is best debated in another thread, the assertion that the AC keeps accelerating after the throttle is closed on the only live engine is relevant to the discussion of asymmetric handling and certification.

My Two bobs worth.

I think the claim that the AC continues to accelerate under these circumstances to be, to coin a phrase from the ABC's Hungry Beast, 'A little bit bullsh*t'.

Aside from the logic of it all, take a look at the Performance graph provided by JT on the previous page.

The acceleration line continues to increase through Vef until 'engine failure recognition point'/V1 (Where the throttle is closed). It then plateaus for a very short time before there is a marked deceleration prior to 'Initial Braking' Vb.

To claim that there is enough residual/run down power in the single live engine to continue an acceleration at speeds up and around V1 after the throttle has been cut is a nonsense.

[43Inches]

In regard to a reject in a turboprop;

1. At the point you recognise an engine has failed it will then take time to act (maybe less than a second but still time).

2. To physically move the PL back to the flight idle stop then over the gate to ground idle will take time. Granted that at V1 the flight idle position will be sufficient to commence deceleration (but will hinder further braking as you slow).

3. Depending on the HMU, FADEC slack in cables etc... the engine will not respond instantly to power lever movement.

All this means is that at the point of recognition power will still remain for maybe a few seconds causing acceleration until the engine runs down to a point drag (braking action) is greater. If the first action is commenced at V1 as required then acceleration beyond v1 will occur, and is allowed for.


(ix) Any residual acceleration that occurs after V1, while the airplane and its systems become stabilized in the braking configuration, must be accounted for in the expansion of accelerate-stop performance data for presentation in the AFM. The effects of system transients, such as engine spin-down, brake pressure ramp-up, spoiler actuation times, etc., should be accounted for in this time period.


From the certification notes.

[john_tullamarine]

Looking back on my initial multi and my continuing multi flying it's concerning how much I wasn't taught

that's our general concern and the fact that the problem is somewhat endemic within the Industry. Unfortunately, it is a case of the blind leading the blind when it comes to some areas of instruction.

I'm not trained in physics

generally not necessary in the same way that we are competent enough to self prescribe an analgesic if we have a headache. The important thing is to recognise that none of us knows it all and that, as a consequence, conservatism is not a bad thing ...

I think the claim that the AC continues to accelerate under these circumstances

we are only concerned with the rundown transient but not the subsequent steady state situation

To claim that there is enough residual/run down

guess we'll just have to agree to disagree.

[remoak]

Ah well, it was only a matter of time before someone started up with the "not on this thread" stuff. Come on fellas, nobody is forcing you to read it, if you don't want to read and/or participate, skip to the next bit!

Anyway...

Nothing more to say about acceleration, the definition of what it is is clear, and the only reason to have that conversation in the first place is that if we are going to use these terms in a technical discussion, we should use them correctly.

For the rest, and in deference to tail wheel and his big rusty padlock, I won't do the point-by-point response thing, I'll just say that we are as close as makes no difference on most of the stuff we are discussing, and for the rest, our disagreement is likely as not a result of different career paths, experiences, and regulatory environments. I won't bother giving you a run-down of mine, as I'm sure some will interpret it as willy-waving, but suffice it to say that it was at a high enough level to be confident that I know what I am on about, in a JAA/EASA environment at any rate. You seem to be in the same situation but in an Aussie regulatory environment. That we can professionally disagree is both a good thing, and helpful in the sense that it stimulates a bit of thinking on the subject.

I spent a bit of time in the Ansett Sim Centre in Melbourne recently, and one thing I noticed was the somewhat different approach that Australian regulators, inspectors and training personnel have to the whole philosophy and practice of checking and training, compared to where I have come from. It is significantly different to the EASA approach, and I think one of the reasons that accidents such as this one can still happen. Having had that experience, it doesn't really surprise me that we disagree over some of this stuff.

Anyway, it was a fun discussion! :ok: Thanks for being such a gentleman in an often aggressive and petulant environment (ie PPRuNe).

[john_tullamarine]

concur.

Next time you're in Melbourne, sing out and I'll organise a small band of like interest brothers in arms for a beer or twenty .. Centaurus might be a starter as well, I should imagine. Like us, he has more than a few definite ideas on these sorts of philosophies and one can envisage a spirited debate .. especially by the fifth round or so ...

[relax737]

A very sad situation has resulted in a lengthy, and very informative, discourse on performance, and one many of us would have learnt at least something from. None of us has a mortgage on all the knowledge.

The protagonists have been very gentlemanly, even gracious in their participation, in what remoak describes as a potentially 'aggressive and petulant environment'.

Well done all.

[john_tullamarine]

.. petulance suits best the sandpit 2-year-olds .... aggression the young Turks of the Industry .... olde pharts are more interested in a beer than a fight ....

[remoak]

Next time you're in Melbourne, sing out

Will do... although I'm a little concerned that Centaurus may want to bat me around the head with something heavy... ;)

[john_tullamarine]

actually a thoroughly nice chap who came out to the Colonies as a young fellow and now has more flying experience than most of us could even contemplate ..

[Mainframe]

Owen Stanley

you've summed up the GA training issues.

Looking back on my initial multi and my continuing multi flying it's concerning how much I wasn't taught

If you were trained by Lester at Caloundra, Bob in Innisfail and a few other good senior instructors around the country you would probably know your stuff.

I have found a lot of GA multi pilots who don't know, or weren't taught some of the vital things, and thus may not be ready for when things do go wrong.

I am now learning and absorbing some things that I didn't know and wasn't taught also,
so if every one else benefits by the rational and factual matters being presented here we can definitely help make the skies safer (for all?)

[RENURPP]

Owen,

You are correct, no one is forcing me to read it, however I keep returning in the hope that some one has posted something of benifit to the original topic, which isn't and has nothing to do with when deceleration begines after closing the throttles!

I am interested in the thread,(under a different name) however if your big head didn't get in the road of logic and you had the know how to start a new and appropriately titled thread I would be able to read the more appropriate posts that preceeded yours.

As Tailwheel has already said Seriously, this debate is so far from the Brasilia accident, I'm inclined to close this thread and you Einsteins can open a new thread on the other forum, to debate calculus, Pythagorus and the Theory of Relativity?

Thread topic debate, or new topic in a new thread?
__________________

There are people who would like to continue reading your thoughts on physics, all I have said is can't you open a thread related to that. When I open a thread on"Air North Brasilia Crash" I sort of expect to find some material/comments or at least discussion around that topic, as we had prior to the physics debate. If that offends, then I suspect I have a good idea who should be playing in sandpits.

Buddy

[FOCX]

Reference: Giancoli's "Physics" IED 6th edition.

Acceleration: "An object whose velocity is changing is said to be accel. For instance a car whose velocity changes from 0 to 80 kph is accel. Accel specifies how rapidly the velocity of an object is changing". pg 23.

As the car is unlikely to be undergoing the same accel throughout it is called average acceleration. Av Accel = change of velocity/time elapsed. Instantaneous accel is the accel during a very short period.

Inertia: Newtons 1st Law. What's at rest will want to remain at rest, what's moving will want to remain moving; unless a force is applied to it, and we're talking about a frictionless situation.

Momentum: A measure of an objects mass and velocity. A 100T truck will require a greater force to stop it than a 50T truck, both traveling at the same spd due its momentum.

F.Nose unless I'm missing something and I'd say this thread is difficult to track, there is nothing " a little bit bullsh@t" about a turboprop accel after losing an engine. How else does it get from V1 to V2 to enroute clb spd, but by accel?

This is my take on a V1 Cut:

Jet: Failure @ V1, a/c accel to VR while dead engine winds down (we're assuming complete failure i.e. no fuel flow), I'd guess it'd be a very short period before it's just drag (measured in seconds), @ VR a/c rotates and continues to accel to V2. V2 should be attained sometime while you're rotating to your engine out attitude, clb out @ V2 until terrain clr height, lvl out and accel to your enroute clb spd. END. Nothing new there!

Turboprop:(MTOW) Same as above, except you now have a huge drag generating device! So with a failure at V1/VR (only turboprop I flew > 5700kg V1/VR were the same) with the Autofeather/NTS doing its job and end up at its minimum drag position i.e. feathered. However if it doesn't due to a failure of some sort and you have complete failure, that is no SHP applied you have a windmilling prop in fine pitch acting as a barn door. It's windmilling due to its areodynamic properties and while you may argue it's generating lift off the prop its got to be bloody minimal compared to the drag it produces. As to momentum of the prop, forget it. Its momentum is a product of its velocity and mass and without any force acting on it, it'll come to a stop (other than windmilling) pretty bloody quick. If an a/c can clb away with an unfeathered prop it aint going far, just to the scene of the accident! Maybe the ace of the base can keep it up, but can he accel, clean up and get it around to land? Remember , the margins in 20.7.1b aren't great.

The certification provides for the average pilot, not Chuck Yeager. I'd be more interested in wanting to fly the a/c as accurately as possible and in accordance with your training, not thinking about knocking off spd for V1, let the performance engineers work that out. If you cannot control yaw you have two options, lower the nose to get your spd above VMCA and /or reduce pwr on the live engine. I don't know about 'real world figues' verses book figures, just that they are all you have, the rest is just a stab in the dark. If it isn't doing what it should, check your config, it is embarrassing when in the sim you hear all this noise and it isn't until you do the after t/o c/l that you find you have left the gear dwn, thank god for a light TOW! Maybe if things aren't going to plan it, and you cannot see the reason and it's turning to ****e, it might be an idea to use your remaining time to select an area to put it down in a controlled fashion instead of aerodynamics choosing an uncontrolled crash site for you. (this is not a comment on the accident, it seemed to unravel pretty bloody quick)

For my thinking Remoak is the one mostly on the money.

[Arm out the window]

Quote:
Thus if at any time the speed (velocity) is increasing, the aircraft is accelerating.

Not in physics it isn't.

Acceleration being a measure the rate of change of velocity, not the change of velocity.

Remoak, I'm not writing to be antagonistic here, but you're not correct, and it's a straightforward and intuitive concept we're talking about which you seem to have a bit arse about, but are discussing from a somewhat lofty-sounding viewpoint.

Any time the speed of anything (in this case an aircraft) changes, it's accelerating (positively when it goes faster, negatively slower). That's it.

Velocity is in miles per hour, metres per second etc, and acceleration is measured in things like metres per second per second, for example, as I'm sure you know.

Say I was doing 10 m/s and I then went faster, to 20 m/s - I've accelerated by 10 m/s. If I did that steadily over 5 seconds, I accelerated at a rate of 2 m/s per second. My average rate of acceleration was 2 m/s squared, or 2 metres per second per second.

The upshot of all this is that any time the speed of an aircraft increases (or in fact changes), it is accelerating.

[remoak]

I'm sorry... I'm not allowed to argue unless you pay...

teMlv3ripSM&feature=fvst

[john_tullamarine]

oh, well done, good sir ... years since I've seen that sketch ... :ok::ok:

[Sand_fly]

Simple make sure MTOW not above 3 Eng MTOW.and enough runway.
Sit on end of runway with 3 operative engines at 60% T off POWER.
Advance the 2 symetrical engines to T Off power.
Apply full rudder to the the side with the most operative engines
Release brakes and keep the aircraft straight by applying power to the remaining engine usually get T off power just before V1
Pray you dont lose an engine on the same side as the inoperative engine.

Similar to a technique used by WW2 Me 109 Fighter pilots to counter torque effect on T off.

[TAC inop.]

WTF.... pray tell how a 109 complies with any acceleration lores with one engine inoperative?

Back to the thread please kids.

[Brian Abraham]

Boeing slide show on V1.

SmartCockpit - Airline training guides, Aviation, Operations, Safety (http://www.smartcockpit.com/pdf/flightops/aerodynamics/41)

From SmartCockpit - Airline training guides, Aviation, Operations, Safety (http://www.smartcockpit.com/pdf/flightops/flyingtechnique/45). See link for full article.

Inconsistent terminology has caused confusion about the V1 concept. An important assumption in the V1 concept today is that the decision to continue the takeoff or reject the takeoff is made before reaching V1. The accelerate-stop performance data in AFMs are based on the pilot flying taking the first action to reject the takeoff at V1.

[For airplane-certification purposes, the actions required to reject a takeoff include applying the wheel brakes, reducing thrust, and deploying the speed brakes or spoilers. The manufacturer establishes the order in which these actions are taken.]

Previous definitions of V1 did not state clearly that V1 is the maximum speed at which the pilot flying must take the first action to reject the takeoff. “[There is] a great deal of misunderstanding and disagreement regarding the definition and use of the V1 speed,” said FAA. “In general, inconsistent terminology used over the years in reference to V1 has probably contributed to this confusion.”

Before 1978, Part 1 defined V1 as the critical-engine failure speed. In 1978, the definition of V1 was changed to takeoff decision speed, and VEF was established as the critical-engine failure speed. V1 also is referred to as the engine failure recognition speed in the FAA Flight Test Guide for Certification of Transport Category Airplanes (Advisory Circular 25-7). FAA currently is revising the circular. FAA’s 1998 redefinition of V1 responded to a 1990 recommendation by NTSB based on a study of accidents that occurred during high-speed rejected takeoffs.

In its report on the study, NTSB said, “Runway overruns following high-speed [RTOs] have resulted and continue to result in airplane incidents and accidents. Although most RTOs are initiated at low speeds (below 100 knots) and are executed without incident, the potential for an accident or an incident following a high-speed (at or above 100 knots) RTO remains high.”

[F.Nose]

FOCX wrote.

[QUOTE]F.Nose unless I'm missing something and I'd say this thread is difficult to track, there is nothing " a little bit bullsh@t" about a turboprop accel after losing an engine. How else does it get from V1 to V2 to enroute clb spd, but by accel?/QUOTE]

FOCX
I'm afraid you missed my argument completely. I wasn't for a minute doubting that a turbo prop (or any other AC) can accelerate on One engine. JT made the assertion (on more than One occasion) that a turbo prop/Jet would keep accelerating for a while after One engine had failed and the live engine retarded to Ground Idle. That was what I was referring to as 'a little bit bullsh@t'.

[john_tullamarine]

I think that one should read what was written rather than making it up as you go along and then ascribing it to a prior post ....

The point about continued acceleration is only relevant to the initial (short) rundown period ... thereafter, the engine provides drag. So far as a failed, as against a throttled back, engine, the only difference is the time history of the rundown and the steady state thrust situation .. the general characteristics are similar.

The pertinent point is that the thrust doesn't disappear instantaneously and, as a consequence, one usually sees a short speed overrun associated with the thrust rundown.

[F.Nose]

[QUOTE]I think that one should read what was written rather than making it up as you go along and then ascribing it to a prior post ..../QUOTE]

Whilst I have better things to do than get involved in a pointless argument I believe that I have indeed carefully read what you have written. I agree with most of your comments and have found them educational however....

These are your words.
[QUOTE]During the rundown period, the thrust progressively reduces, resulting in a speed overrun with a hump such as shown generically in the Boeing sketch. Just the way the real world works, I'm afraid./QUOTE]

Can you please explain where this hump is because I see a very small horizontal line... representing Inertia, followed by a marked down curve...deceleration.

I agree that an engine will not go from T/O power to ground idle instantaneously when the throttle is cut... However the power required to keep an AC accelerating on 1 engine will be very quickly lost (as near a damn it to instantaneously) once the throttle is slammed shut. It does not have to get anywhere near ground idle.

[43Inches]

(ix) Any residual acceleration that occurs after V1, while the airplane and its systems become stabilized in the braking configuration, must be accounted for in the expansion of accelerate-stop performance data for presentation in the AFM. The effects of system transients, such as engine spin-down, brake pressure ramp-up, spoiler actuation times, etc., should be accounted for in this time period.





F.Nose - this is straight from the certification guidlines and indicates that acceleration may occur after V1, included in the factors is engine spin-down.


Engine spin/run/spool-down acceleration is allowed for in the ASDR calculation. This means someone has measured it and proved it exists in at least one aircraft.


JT is just providing a reason as to why this is.

[john_tullamarine]

These are your words.

Indeed .. I definitely wrote that ... however, my words didn't include ..

would keep accelerating for a while after One engine had failed and the live engine retarded to Ground Idle.

.. the bean counters would love such an aircraft .. one could forget about fuel hedging and like sleepless night matters ..

Can you please explain where this hump is because I see a very small horizontal line

.. it would appear that one man's hump is another man's horizontal line ?

[F.Nose]

[QUOTE] This means someone has measured it and proved it exists in at least one aircraft./QUOTE]

If that is the case (and I still believe it to be negligible) it is not depicted in the Boeing performance graph that JT provided and claimed proved it's existence. In fact the Boeing graph clearly shows a deceleration prior to even the application of brakes.

[QUOTE]
.. it would appear that one man's hump is another man's horizontal line ?/QUOTE]

In my books a hump is a hump. A horizontal line is when you just fall asleep.:zzz::)

[remoak]

Not really wanting to get back into this, but just for the sake of clarity...

http://www.simavia.co.nz/sodetail.jpg (http://www.simavia.co.nz/sodetail.jpg)

This is a detail of that graph. I have added emphasis lines to show more clearly, vertically, the line that represents "ground run to engine failure recognition", and horizontally, in red, "Takeoff decision speed" and in green, the plane where the vertical "ground run to engine failure recognition" line intersects the acceleration curve.

It should be pretty obvious from this detail that the acceleration curve does not go any higher than the point where it intersects the "ground run to engine failure recognition" line, although of course it does go slightly above the "Takeoff decision speed" line.

So... from this graph, it would appear that acceleration does NOT increase above the point where the failure is recognised.

The only real question in my mind is what kind of acceleration Boeing are talking about, because that looks more like a raw speed curve to me...

Anyway... back into my hole now... :ok:

Now whether that is what the graph is trying to tell us, and how much might have been lost in the scanning/copying process, I leave to you... :}

[remoak]

Actually when I re-read this thread, I am reminded of this...

_f_p0CgPeyA

[john_tullamarine]

One needs to keep in mind that the particular Boeing graph is generic.

[remoak]

Maybe, but one assumes that it is meant to represent the situation with it's own products... and whichever way you slice it, it simply doesn't show an acceleration past the point of the recognition of the failure.

Do you have any other info on this?

[43Inches]

Sorry but the certification requirement is that the first action to abort be commenced at V1, engine failure recognition occurs before v1 not after.

The graph might be slightly in error to fit the wording in.

If you recognised an engine had failed after v1 would you stop?

[PT6]

Having undergone Sim training in the Emb120 sim and having experienced an engine failure just after V1 without autofeather operating, I can vouch for the need for prompt and correct actions from the PNF. I would not agree to doing this in the aircraft EVER! My sim buddy and I crashed in the sim trying this the first time.

Using the Sim is cheap if you save lives and a hull and as others have said here you can learn so much more after a couple of sim hours than 2 hours in the aircraft.

Very sad for the families involved. All Emb120 operators should in my opinion use a Sim for EFATO and control malfunctions training. At least Asymmetric flap cannot be simulated in the aircraft, as that is a potential killer too along with windshear and upset recovery.

[PT6]

As a Type Rated Emb120 pilot with Check & Training approval I can confirm that this aircraft performs very well following an engine failure. If the dead emgine Autofeathers it is all easy and nothing much to do until reaching acceleration altitude. At moderate weights it will climb away at 1500fpm. If it fails to autofeather then the PNF must feather the windmilling (high drag) prop immediately. If it still fails to feather (now it gets nasty) the electric feather pump must be activated immediately. If this is not dome you have very high drag from the dead engine and 1800shp from the good one. Soon you run out of rudder and the aircraft will roll to the dead engine as you are still at a relatively low speed and VMCa now becomes an issue. The rest you can imagine.

Hence my comment that this type of training (all engine failures during/after takeoff and control failures/abnormals ) should only be done in the Sim. This policy is a published international airline standard for good reason.

[FGD135]

Excellent posts, PT6. We thank you.

How do you know that the prop has feathered?

Is takeoff permitted with an autofeather inoperative? Do you test the autofeather prior to every takeoff, or once only at the start of the day?

[downunderscouser]

I am trying to understand something here... how would autofeather kick in if the engine has not actually failed? I am under the impression from talking to ex Air North pilots that the 'dead' engine has it's power pulled back to around 10% torque. The airplane will surely not autofeather since the engine is still running.

Can someone clarify please?

[PT6]

FDG135. Yes Auto-feather is tested after every start. It arms at 64 Deg. power lever angle as levers are advanced. Call is Auto-feather Armed. Otherwise call is Auto-feather not armed. I can't remember the MEL but I believe dispatch is allowed without Auto-feather operative subject to a few conditions which may have included a weight reduction penalty. Not sure on this one. It may have been a no-go item. Prop is considered feathered when prop rpm drops to 10%. Same as on the Saab 340B WT. Same props. They do not stop rotating in feather just go to a min. drag angle.

Auto-feather will operate when torque drops to less than (now I am stretching my memory) something like 40% as long as there is significant torque at the other prop. I can't recall the actual figures. I have never seen this system fail during a take-off. In my experience it always armed (provided someone remembered to turn on the switch!). Pulling back the power lever would cause an auto-feather if it was turned on and armed. It can Auto-feather with the engine running.

[xxgoldxx]

PT6..I dont fly a Bras but I reckon you might be wrong about auto feather working by reducing power on one engine...
In similar aircraft it also relies on both power levers being above "X%" Tq and above a certain PLA.. hence why zero thrust is used to simulate the feathered eng..

[Mount'in Man]

The B1900 requires both power levers to be set above 90% N1 to arm AFX. Retarding a power lever below that setting disarms the AFX hence the need to set zero thrust on the failed side when simulating ‘engine failed & prop feathering’.

A more sinister issue with the B1900 (I don’t know about the EMB120) is failure of rudder boost as this would require considerably greater rudder pressure by the pilot to control the aircraft. In other words, failure of rudder boost will increase minimum control speed. If my memory serves me correctly FAR 25 sets maximum rudder pressure of seventy pounds at VMCa.

AFX and rudder boost are both pre-flight check items, and are required for dispatch.

[Josh Cox]

PT6,

I have not flown a Bras.

Pulling back the power lever would cause an auto-feather if it was turned on and armed. It can Auto-feather with the engine running.

Whats the point of having the micro switches ?. Wouldn't it stand to reason that with the Auto FX switch on and both levers up would be required to have the system operative ?.

I do not believe the prop will feather if you pull the power lever back in normal operations with Auto Feather armed, I believe it would have to be an actual failure:

Here: SmartCockpit - Airline training guides, Aviation, Operations, Safety (http://www.smartcockpit.com/pdf/plane/embraer/EMBRAER-120/systems/0004/)

Page 11, 62 degree PLA...

B200 and Metro 23, from memory both the power levers need to be up to arm the system.

[Dog One]

I think you will find that the power levers have to be advanced above 63 degrees PLA to arm the AUTO FX, and for it to operate, there has to be a significant drop in TQ, which activates the system.

Auto FX used to be left on throughout the flight, but after a few unintentional auto FX's at cruise power due lost of TQ signal, most operators changed their SOP's to switch off after take off and on before landing.

Auto FX is one of the take off warnings, so I think from past memory it was a no go item

[mattyj]

AFX and rudder boost are both pre-flight check items, and are required for dispatch

I don't know if rudder boost is a no go item..have to check the mel next week but I wouldn't assume it is..its not even fitted on the B1900C

To check the Auto feather before flight the Autofeather switch is placed in "test" not "arm" because it only normally arms at greater than 90% n1 as said above..the system only works if one engine is running at high power while the other drops below the set figure..depending on model of 1900..if both powers drop together neither prop will feather. I can't find a reason why pulling one power lever back while the other is up wouldn't cause an actual autofeather if the side you pull back is still running..you might need it to like some sort of FCU failure where the engine rolls back but doesn't shut down.

With the PW100 series the Autofeather depends on an oil pump I'm told, and if this fails the prop fails into fine..high drag/windmilling (never flown one can't confirm)..unlike the pt6 which eventually goes into coarse with loss of oil px

[Chimbu chuckles]

If its anything like a Bandit (E110) AFX system to test it you held down a spring loaded switch while advancing both power levers up to a certain tq setting and then reduced one - it auto feathered - advance that power lever and it un feathered then repeat on the other engine. Armed for takeoff, and with the power levers above whatever the PLA was, if the system sensed a fall in tq/oil press, or however it worked, below a certain level with the thrust lever still fwd it auto feathered the prop on the failing engine.

So merely reducing power on one engine to simulate engine failure would NOT cause autofeather - on training flights it was a manual system - I'd be surprised if the EMB120 works much differently.

I haven't flown a Bandit since 1994 so all this is purely from memory.

[mattyj]

Oh yes I have had a re read and the power levers must be up past a microswitch for afx to be armed..reducing power by pulling the lever back disarms afx so won't cause prop to feather at low power settings on pt6..cheers CC

[Grogmonster]

Josh, Chimbu and co you are all correct. With power levers advanced and auto feather armed both AFX lights illuminate. If one power lever is intentionally retarded that prop wil NOT feather. That is why you have to simulate that it has feathered by using 10 - 12% TQ. If you had an FCU roll back with both levers advanced and AFX armed the affected prop will feather.

It frightens me that some people, posting here, don't seem to grasp this basic understanding of the aircraft sytems that they are flying. Or perhaps thay are not flying and a little bit of Knowledge is dangerous. Api noon Chimbu.

Groggy

[Dog One]

The system in the 120 is a more refined version of the 110. Looking up some hand written notes, the system has mechanical feathering by the condition lever or electric feathering vis the electric feathering pump. This pump is activated by the electical feathering switch, the Auto Feather System, the fire handle, or the prop aux pump test button.

The electrical feathering solenoid is activated by the electrical feathering switch, the Auto Feather system, the Fire Handle orthe Flight low pitch micro switch.

The daily check of the Auto FX system is to use the prop aux test button to run the blades out of feather position and then use the electric feather switch to run the blades back to feather. This test checks the proper operation of both the electric pump and the electric solenoid valve.

Auto FX is armed when
Auto FX switch is on
Power lever angle is greater than 62 degrees
Torque on both engines > 62%


The Auto FX will activate if the torque of one engine is < 23.6% with a 1/2 second delay.

[#1AHRS]

Auto FX, Uptrim, V1, VR all very nice and technical but when are we going to get real. Train it in the SIM..! Thought we were supposed to have learnt that lesson in Tamworth.

[LeadSled]

Thought we were supposed to have learnt (sic) that lesson in Tamworth.

#AHRS,
Clearly not, based on the number of asymmetric training fatalities since the Metro at Tamworth, and some bloody close goes, three at least that I am aware of, which also involved Metros.
Tootle pip!!

[maralinga]

Oz aviation...still working towards the lowest common denominator

[bushy]

If it is too dangerous to carry out these procedures in RPT aircraft with only the crew aboard, then let's stop pretending that these aircraft have the magic ability to perform these manouvers with a full load of passengers aboard.
Either the aircraft cannot do it safely, or the crew training should improve.

[Arm out the window]

Not so straightforward as that Bushy, I'd say.

While I agree most aircraft can perform assymetric drills and recoveries without incident, the sad fact is that in a significant number of cases (ie. enough so that most of us can name people we know who've been killed in them - or perhaps that's being a bit too general; I know I can, anyway) aircraft and lives are lost.

For every one that spears in, there'd be what, 5 more who scare themselves? Dunno, but it'd be up there somewhere. If modern sim training can do the job realistically enough, then there's a good argument for using it, particularly when you can offset the cost of doing it in the sim against hours not flown in the actual aircraft.

Also, you can take things further in a sim than in the real case, so arguably the training's better. I'm fairly old school in regard to my own training in various types, ie most emergency training done in the real thing, but I don't see the point in doing potentially dangerous stuff airborne when you could do it (hopefully cost-effectively) in a simulator.

So it's a furph to ask 'Is it too dangerous?'. The question is, is it dangerous enough that we should mandate use of alternative means of training where they are reasonably available?

[greybeard]

The use of Simulators should be mandatory.

I did 19 years on the F-28, NO simulator, although they were available, all 10 hours of endorsement requirement for both F/O and Command, all renewals with only a DME homing being done in the Frasca. Other bases of Ansett did make use of the one in Indonesia.
Went to TAT in France, into the Sim, like a breath of fresh air, learnt a lot in just the short time we were there. Similar in Belgium with DAT.

With the Lear also the majority was also in the Simulator, who wants do do NIGHT stalls and high rate descents over the water, in the storms, half way
to Kuching at 0200. Scared me spitless, the cadets even worse.

Larger A-310, all work done in the Sim, likewise the F-100 for various operators.

For my sins I have 3000 hours as a Simulator Instructor, it is the greatest aid to training, regrettably it can be the destroyer of any or all if misused by the Airline or the Instructor at the panel.
There is no sense to me in shutting down or failing any system on a perfectly servicable aircraft. There are too many tragic results in the system from GA, Airlines and our own RAAF from the accidental/deliberate failure of syatems and regrettably the ego or some of the check/trainers can be a factor, more easily survived in the Sim.

I dont know the cost of a Brasilia Sim, it has got to be cheaper than this tragic loss.

Be safe out there, I drive a Bus full of kids, that can be tough, no Sim there, all done live!!!!

:ok::ok:

[Dashunder]

Off Subject, but on a sad note.

One of the Pilots on this flight (SW), father died on Saturday night

[Jabawocky]

Yes thats true. Harry was not well before but seemed to have dropped the will to push on.

One of the other sons (Shane's Brother) is a LAME and ex Air North, and still in the industry back down here.

Funeral this Friday.

J:sad:

[Centaurus]

Tootle pip!!

This Tootle Pip thing is like a Chinese water torture of the dripping tap. Exactly what is the bloody thing?

[remoak]

Old fashioned upper class slang for 'goodbye'.Toodle-pip is a variant of 'toodle-oo', from the French a tout a l'heure, 'see you soon'

Why thank you Mr Google...

[AerocatS2A]

Agreed on the Chinese water torture effect of "toodle pip". I understand the desire to distinguish yourself from the crowd but can't you just wear red socks or something?

[VH-MARIA]

Hi Leadslead,

In regard to your point on the inherent dangers of conducting simulated asymmetric training in multi-engine aircraft - while I agree, is it still a legal requirement to conduct asymmetric training in Australia (simulator or no simulator available relevant to the aircraft type) for the aircraft type yoy want to be endorded on - ranging from say a Brasilia to PA31 to Patrenavia? - or, is it generally classified as non emergency type training and the asymmetric component is not legally required to be flown as part of an endorsement for this type of aircraft. Do the CAO's permit this?

I was under the impression that asymmetric operations were a necessary (legally required) component of a twin endorsement for a particular twin type (Navajo, C402, Baron etc) as they do have different handling characteristics to varying degrees). As a multi-engine instructor on several types of light multi-engine aircraft, I would be grateful for your thoughts and the thoughts of others please?

Thanks.

[Kelly Slater]

To find out what happens if you choose not to do assymetrics in an endorsement, read the thread "WA Air Operator sues CASA and officials" in DG & P General Aviation.

[betaman]

VH-MARIA

In regard to your point on the inherent dangers of conducting simulated asymmetric training in multi-engine aircraft - while I agree, is it still a legal requirement to conduct asymmetric training in Australia (simulator or no simulator available relevant to the aircraft type) for the aircraft type yoy want to be endorded on - ranging from say a Brasilia to PA31 to Patrenavia? - or, is it generally classified as non emergency type training and the asymmetric component is not legally required to be flown as part of an endorsement for this type of aircraft. Do the CAO's permit this?

I was under the impression that asymmetric operations were a necessary (legally required) component of a twin endorsement for a particular twin type (Navajo, C402, Baron etc) as they do have different handling characteristics to varying degrees). As a multi-engine instructor on several types of light multi-engine aircraft, I would be grateful for your thoughts and the thoughts of others please?

Thanks.


As a multi-engine intructor on several types of light multi-engine aircraft. Shouldn't you know the answer to those questions?:hmm:

[Monopole]

If it is too dangerous to carry out these procedures in RPT aircraft with only the crew aboard, then let's stop pretending that these aircraft have the magic ability to perform these manouvers with a full load of passengers aboard.
Either the aircraft cannot do it safely, or the crew training should improve.

bushy, I dont think that it is that the aircraft cannot perform, but rather how the failure is conducted.
I have done countless (simulated) V1 cuts on the Braz, and never was the prop feathered for real. Only touch drills. That leaves 4 great big paddles windmilling in the breeze.

The practice of reducing power on the remaining engine to simulate hot and heavy loads is, in my opinion bull:mad:. It was to prevent running out of rudder authority.

It would be nice to believe that with the prop feathered then the aircraft would have the "magic ability to perform these manouvers with a full load of passangers on board".

[bushy]

It is licensed to do that type of operation on the assumption that it can. If it cannot do it safely let's stop pretending that it can.

[ResBunny]

The preliminary report is on the ATSB website:

http://www.atsb.gov.au/media/1518296/ao2010019_prelim.pdf

Regards

[steelcraft]

Shows that the company appears to have the best intentions but it took CASA 6 weeks to issue a bit of paper.

[downunderscouser]

Nothing new in that report really, looks like a long wait till the investigation is completed...

[topend3]

I note on seek yesterday an advert for a safety and compliance manager...

[Tee Emm]

Nothing new in that report really, looks like a long wait till the investigation is completed...Apart from the fact the ATSB report said the engine was (simulated) failed one second after getting airborne. Regardless of the experience level of either pilot, the risk factor of a mis-handled engine failure that close to the ground must be tenfold more than a simulated failure at a safer altitude. I am sure there are many instructors who have multi-engine training qualifications that have been caught by surprise after pulling an engine on a student shortly after lift-off that the student has instantaneously and of course inadvertently, banged on full wrong rudder. Having had such an experience and surviving it most instructors would be very cautious at pulling an engine at extremely low level. It is simply not worth the potential risks involved.

A long time ago and following a series of multi-engine training accidents involving simulated engine failures after take off, the NTSB observed , quote: "that many flight instructors down through the years, used the technique of abruptly cutting an engine with a multi-engine candidate to test his emotional reaction and judgement with this extreme technique". The recommendation observed that use of such procedures at traffic pattern altitudes may not permit enough time to overcome possible errors on the part of the applicant.

Let's face it -it is an extreme technique to pull an engine one second after lift off. Best of luck to any instructor that tries it - he may need it....

[megle2]

Agree Tee

A side point

What if the pilot being checked decided the required Casa "tick the box EFATO" was in fact unsafe and simply, if it had been possible prior to retracting the U/C landed straight ahead (assuming distance remaining was not a limiting factor).

Would he have failed the check for going against the brief or would the checker have failed for instigating a potentially unsafe exercise.

[The Green Goblin]

Both the prior posters must not have an understanding of transport category aeroplanes.

A failure at V1 is perfectly controllable and the subsequent rotation and flight is all within the capabilities of the average (or below average Pilot for that matter) Pilot and briefed as such prior to every takeoff. When comparing that to light piston twins then of course you would not pull the mixture/throttle prior to a safe height.

As part of a base check you will have a V1 engine failure and have one simulated every renewal/proficiency check thereafter. Whether that is in the sim or the aeroplane makes no difference. Whilst the attention is on the Pilot being checked to perform the maneuver safely the onus is on the check Pilot to conduct the operation safely and to be ready with the levers and rudder if required.

In this game we play for keeps - Ernest Gann

[john_tullamarine]

Both the prior posters must not have an understanding of transport category aeroplanes

Can't speak to megle2 but Tee Emm has more heavy transport hours than you and I put together a couple of times over, I suggest ..

A failure at V1 is perfectly controllable and the subsequent rotation and flight is all within the capabilities of the average (or below average Pilot for that matter) Pilot

... providing that the circumstances on the day reasonably replicate the certification envelope .. one of the questions which our good friends at ATSB will be looking at closely is whether this was/was not the case for this mishap. In this respect we are considering crew, aircraft, weather, etc., etc ...

It is important not to infer guarantees with performance .. there is a measure of variability and statistical inference involved with all this stuff .. and, if one goes out on a limb a bit too far ... all bets can rapidly be off.

Whether that is in the sim or the aeroplane makes no difference

.. except to the extent that, in the sim, if one screws up, the others get to have a bit of a chuckle .. in the aircraft, the families might get to bury the crew.

landed straight ahead (assuming distance remaining was not a limiting factor).

purely speculation but I suspect that such would not have been an option for this event and any typical crew. In the lower weight end of the envelope, and depending on the speed schedule and systems handling, things can happen VERY quickly and, unless the crew is onto the problem correctly and rapidly, the ground sometimes wins ...

My comments don't necessarily apply to the mishap .. we need to wait awhile for competent investigation results.

[BombsGone]

Goblin,
By all means disagree with the previous posters but don't start by denigrating them as being poorly informed. As Tee Emm states the use of opposite rudder by mistake happens. This can rapidly lead to an unrecoverable situation in transport category airplanes. This may not be the case here I'm not assuming anything, but do you really learn that much more by simulating failure at rotate as opposed to above 500' or 1000' as I have seen in some ops manuals? If so is the risk worth it?

[remoak]

A failure at V1 is perfectly controllable and the subsequent rotation and flight is all within the capabilities of the average (or below average Pilot for that matter) Pilot

... providing that the circumstances on the day reasonably replicate the certification envelope .. one of the questions which our good friends at ATSB will be looking at closely is whether this was/was not the case for this mishap. In this respect we are considering crew, aircraft, weather, etc., etc ...


I think it is fair to say that, from the evidence we already have, the conditions on the day were benign and well within the certification envelope (if not pretty much ideal), and that the crew were considered to be above-average pilots. It would therefore appear to me, at any rate, that this is going to come down to either a bizarre mechanical failure, or crew error. My money is firmly on crew error, although I would be the first to apologise if it turns out to be a mechanical failure.

However I do agree with Green Goblin, an astute and professional check pilot will always make sure that the trainee can't kill him. When conducting any form of multi-engine assymetric training, I always have my foot hovering just above the "correct" rudder pedal, ready to counteract an incorrect input, and a hand close to the power lever ready to restore power if required. If you are going to do this sort of stuff close to the ground, you are absolutely crazy if you don't take precautions.

Yes, using the wrong rudder input will very quickly allow an unrecoverable situation to develop - however, a smart check pilot will never allow this to happen in the first place.

My gut feel for this accident is that the check pilot was probably complacent, and the trainee simply made a fundamental error.

I would have to agree with Tee Emm 100% as well. The Brits were very smart to mandate, after the J31 accident at Prestwick, that EFATO exercises be carried out at 500' AGL or above. Quite a few trainers in my company at the time (also a J31 operator), felt that the exercise was pointless unless carried out within half a second of V1, but then these were the same people (all ex-RAF) that took the view that the primary purpose of training was to load a trainee up until they lost the plot and screwed up. The secondary purpose of training was to then berate the trainee for their failures in as intimidating a manner as possible - preferably in public.

I have noticed, following a recent visit to the Ansett Sim centre in Melbourne, that the "load 'em up until they break" approach seems to be fairly well entrenched in some Australian training practices.

Thankfully, most of us are a little more enlightened these days (although ex-Forces people seem unwilling to let their old methods go).

As far as I am concerned, if you can't afford to do asymmetric training in a simulator, you can't afford to operate that type, period.

[BombsGone]

Remoak It would be nice to see one thread that does involve a civil versus military pissing contest. I vigourously agree with most of your thread but I think you'll find the style of instruction in the military is vastly different to your opinion.

[remoak]

It isn't opinion, it is first-hand experience...

[BombsGone]

Remoak your post implied that most exmilitary pilots have a load them up view of training, and believe dangerous practices are acceptable. This is a gross generalisation and not reflected in my experience.
The military safety culture has changed significantly in the last 20 years and accident rates will bare this out. It is not the people but the culture of "this is a dangerous game accidents will happen", that was to blame. This seemed to be implied by Goblin as still OK in his closing line.

An example: Double asymetric training in aircraft. Resulted in one fatal accident and several near misses. The airforce lost several lives and a lot of respect because it did not learn from civilian experience here and transfer the training to a simulator earlier.

What you and green goblin have stated about guarding against student errors is instructing 101. Given that once you have an ATPL you can magically become a check and trainer without any training experience, I hope that companies insist on teaching such basic survival techniques and include them in what the military would call an instructor guide for any given training event. A proper instuctional technique course would be nice.

The discussion here has centred around whether asymmetric training should be mandated in the simulator. I had a quick search of the NTSB web site and found 51 accidents in the last 20 years with asymmetric thrust as a factor. None that I could see was a training accident but a significant number involved poor handling of the emergency. Food for thought. As for opinion, a good simulator as many earlier posters have stated, can give far better emergency training than the real aircraft.

Enough from me I will await the eventual report.

Happy flying

[FGD135]

A failure at V1 is perfectly controllable

Yes, but this was a simulated failure, and simulated failures can make for a less controllable aircraft than a real engine failure.

[remoak]

BombsGone (hmmm, not ex-military are we...)

Well my experience of ex-military pilots is somewhat different. I have flown with about 50 of them, in various capacities, and have found them, with one outstanding exception, to be generally arrogant, overbearing, and disdainful of civil pilots. I have experienced the following:

- one ex-Lightning pilot who thought it was OK to perform aileron rolls in a Jetstream 31 during recurrent checks;
- one who thought performing "buzz and break" manoeuvres was acceptable with pax on board;
- One who I had to fail on a Line Check, because he called visual whilst he was not only IMC, but after he had just flown through the localiser at 90 degrees and had no idea where he was relative to the runway;
- one ex-fast jet guy who failed his F27 conversion because he simply could not fly in a straight line - I kid you not;
- one ex-military instructor who hit me across the head while I was flying, sending my headset down under the rudder pedals, because he didn't like the way I was flying the approach. His rationale was that he had got away with a lot worse in the RAF;
- one who used to request that USAF fighters do practice intercepts on our aircraft over the North Sea ("embellishing"), scaring the crap out of the pax in the process;
- one who disappeared from a conversion course for three days to go on a binge with his squadron buddies, stating that "military matters" were more important than the training;
- one who we had to fire after he had six altitude busts in a month in the London TMA;
- and, of course, all the tossers who simply can't fly without their treasured ex-military flying gloves, and the ones who go on and on about how ****-hot they were in the military, and who treat all civil pilots with contempt.

And that is the very short list of my experiences with ex-military pilots.

In my experience, ex-military pilots do not always adapt well to civil flying, because the very qualities that made them selectable to the military, are undesirable in civil flying. Try explaining CRM to a lot of ex-fast jet guys and see how far you get...

I don't know about Australia, but in the UK there are whole airline flight departments that are nothing more than RAF Old Boys clubs. The Chief pilot simply loads the company up with his ex-squadron buddies, irrespective of skill or competency. In one airline I worked for, the Fleet Training Manager was caught filing positive recurrent check paperwork on fellow RAF alumni, when no check had actually taken place. I mean, why go to all the trouble of actually checking these guys? They are ex-Forces, how could they not be competent. He got fired for that after the CAA did an audit. Guess where he ended up? The CAA, another bastion of ex-RAF types.

Don't get me wrong, there are some good guys out there, but there are others who simply can't let go of the giant Boy's Own adventure that their military service was, in their minds at any rate.

Anyway, to answer your points:

This is a gross generalisation and not reflected in my experience.

It isn't a gross generalisation because it IS reflected in MY experience.

Given that once you have an ATPL you can magically become a check and trainer without any training experience,

Maybe you can in Australia, but in the Civilised World you can't. In JAA/EASA land, you have to go through the TRI Core Course before you can do any airline-level instruction, and quite a long process of discrete CAA courses and sim sessions before you can actually become a sim instructor or TRI. It isn't easy at all.

I hope that companies insist on teaching such basic survival techniques and include them in what the military would call an instructor guide for any given training event. A proper instuctional technique course would be nice.

Again, in JAA/EASA land, most of that is included in the company Training Manual.

None that I could see was a training accident

Apart from this one of course, and the J31 fatal accident at Prestwick, and the night asymmetric training accident involving a SA227-AC Metroliner, VH-NEJ, at Tamworth on 16 September 1995, and numerous other in the US. If you go back in RAAF history you will find many training accidents while doing asymmetric training, from various wrecked Hudsons in the '50s down to today.

Enough from me I will await the eventual report.

Well after reading the Whyalla Airlines report, I wouldn't hold your breath... :=:=:=

[john_tullamarine]

from the evidence we already have, the conditions on the day were benign and well within the certification envelope

the crew were considered to be above-average pilots

that's the weather and crew taken care of, I guess .. now, what are your views on the other considerations ... for which we have, as yet, not much information of which I am aware .. ?

My money is firmly on crew error

I knew neither of the crew so I have no view on their abilities or standards. Regardless, has there been any hard evidence presented to date to suggest that they made an error ? The ATSB may discover that that was the case but, in the meantime, I think that we are better served keeping our counsel on matters of total speculation ? While not particularly wanting to get into speculation, I think it might be interesting to see what the investigation digs up in respect of aircraft systems and C&T systemic problems.

however, a smart check pilot will never allow this to happen in the first place

The sensible instructor will endeavour to do so .. however, sometimes strength and timing wins out .. I recall a mate who, as a helo instructor, couldn't prevent a student's mishandling of the collective during an autorotate flare with unfortunately predictable results. I like Tee Emm's attitude .. why put yourself in a potentially very marginal situation if you don't really need to do so ? History indicates that many fatals have been associated with training to avoid the fatal being trained for .. if that makes sense ..

While never having flown as a military pilot, I have had extensive involvement with such folk both in and out of the military .. I'm a tad confused as to why we are moving into military versus civil arguments ?

[Compylot]

In this game we play for keeps - Ernest Gann

Well by quoting E.K. Gann at the end of a post, then surely you would have to know what you are talking about!

[remoak]

that's the weather and crew taken care of, I guess .. now, what are your views on the other considerations ... for which we have, as yet, not much information of which I am aware .. ? I don't have any. That would be speculation... :=:=:=

Regardless, has there been any hard evidence presented to date to suggest that they made an error ? To be slightly mischievious...

Facts which at first seem improbable will, even on scant explanation, drop the cloak which has hidden them and stand forth in naked and simple beauty - Galileo

It is an old maxim of mine that when you have excluded the impossible, whatever remains, however improbable, must be the truth - Arthue Conan Doyle

In other words, yes it is possible that some obscure technical failure put the aircraft beyond the control of the pilots... but I think we all know that it is unlikely.

I like Tee Emm's attitude .. why put yourself in a potentially very marginal situation if you don't really need to do so ?As I said, I agree 100% with TM, however that isn't the real world. Unfortunately, in Australia you still allow this sort of training to be carried out in the aircraft when simulators are available, so if you find yourself carrying out these manoeuvres in the aircraft... be prepared.

I'm a tad confused as to why we are moving into military versus civil arguments ?Because military training methodologies have been, in the past at least, overly aggressive, and their proponents have been prepared to accept a much higher level of risk in an effort to load up the candidate and weed out those without the "right stuff". This way of thinking has spilled over into the civil world, as military pilots have entered civil flying jobs, and has been a factor in many training accidents. I don't know whether any of the Air North trainers are ex-military, but if so, it could explain the reluctance to use simulators and ergo this accident, at least in some part. It certainly shouldn't be ignored.

[Jabawocky]

There was a sim installed but at the time of the accident they were only just getting the approvals etc to use it sorted......almost in time.

[remoak]

Yes but Brasilia simulators have been available in the USA for many years. No reason at all why Air North couldn't have used them, they are all FAA/EASA certified which is more than enough for CASA I would think.

Mt Cook airlines in NZ have been, until very recently, sending their ATR crews to Thailand for recurrent training... it's just the cost of doing business. If you can't afford to train in the sim, you can't afford to fly that type.

To me, the real issue is that CASA allow this type of training to happen when sims are available - whether they are in Oz or not.

[Brian Abraham]

the real issue is that CASA allow this type of training to happen when sims are available - whether they are in Oz or not
It all comes down to economics the companys argue. The worlds largest company runs an offshore helicopter operation in Australia and captains get to visit the sim in the USA once every two years. Copilots don't get to attend at all, yet they are doing 50% of the hands on flying. Why? The bottom line - cost. I know, I know, if you think training is expensive, try having a...........

[triadic]

Folks!

I am not prepared to discuss the accident in question, however a few points have been raised in recent discussion that I feel deserve some comment:

As an experienced training Capt on Transport category aircraft including the days when a sim was not available, I have conducted all training sequences in the aircraft including engine failures and in some cases after V1 with all 3 wheels still on the ground (prior to Vr) and fly away. Yes, there is a risk, however I suggest that good training techniques, good planning in conducting the sequences and appropriate briefings are all good mitigators against the identified risks. Once upon a time there was no choice as Sims for many aircraft were not available.

Australian CASA requirements for Training Captains are weak to say the least and in many cases approvals are given to pilots with no training background or experience whatsoever. I have always considered this inappropriate at best and it is good to see some changes filtering thru the system these days. Once upon a time it was rare to find a pilot that at one time or another had not been an instructor in GA, that is now not the case and many of these non-instructors are put in a training position with minimal or no Instructional Technique training. I have always believed that a basic instructors course should be part of any training pilot approval.

Nevertheless, the boys clubs still exist and many training departments are full of the mates of Chief Pilots and/or Head of Training etc. regardless of their training background (or lack of) and even their ability to instruct. How some of these pilots can successfully plan a training mission and minimise all the risks is often I believe just good luck. I wont even mention assessment standards and how they are achieved!

Since the introduction of Sims the ego of some training pilots to engage in sequences that might only be carried out in the sim surfaces from time to time and in fact I have seen some of these ego maniacs try some of this stuff in the aircraft, surviving (sometimes) only due to good luck rather than good management! I have no idea what they are trying to prove? (the push em till they break attitude perhaps?)

Sims have their place and are an excellent tool for conducting training, especially in those sequences that have a high level of risk. I believe it is unfortunate that some training pilots and perhaps some training departments don't endorse ego free training in order to get the best value out of the time and effort that is applied. Ego is part of human nature but in this business unless perhaps you are a fighter pilot (where it helps to survive), it should be left at the flight deck or sim door!

[43Inches]

Since the introduction of Sims the ego of some training pilots to engage in sequences that might only be carried out in the sim surfaces from time to time and in fact I have seen some of these ego maniacs try some of this stuff in the aircraft, surviving (sometimes) only due to good luck rather than good management! I have no idea what they are trying to prove? (the push em till they break attitude perhaps?)

I think this is more a case of a little knowledge is dangerous in that they don't appreciate the fact the sim exercise is to prove how marginal a situation is. The sim exercise is not to prove you can get away with it but rather instill in the pilot a procedure which will most likely result in success.

The proof of this is previous posts regarding aircraft climbing with a propeller which fails to feather and continues to windmill. Yes the sim may say its possible and some incidents in the past the crew may have had similar situations in which they were able to climb, but is this the case always?

At least one bras was not even able to maintain altitude after a powerplant failure, let alone continue a take-off sucessfully (not refering to the Air North accident).

Whilst training a V1 failure in the aircraft was necessary without simulators as mentioned before it always carries a greater risk than a normal departure. Throw in even a small system failure on top of a simulated failure and confusion and loss of control can occur, a simple distraction at the wrong moment is all it takes.

Any instructor who has had a student lock up on them during sequences like stalling knows the risks involved in any abnormal operation. Any way of mitigating the risks should be taken. Assymetrics and emergency training in large aircraft should be in the simulator as the risk factor everything considered is very high.

[greybeard]

In my earlier post in this I eluded to the egos, competency and suitability of the Check and Training people.
More has now surfaced in this area, and the old chestnut of Military vs Civil as well.

It is so VITALLY IMPORTANT that the people charged with the resposibility of our standards are suitable, well trained, audited regularly and can leave their egos at home.
The use of any training sequence as a "load to they break" should be eradicated from the system, probably an impossible task without an extensive search and find audit of many companies, as we all resist admitting our errors/mistakes and choices, particularly Management.
As a canditate, if you feel the process is unrealistic, stop the check or training, put the Sim on the blocks, land the A/C and go home.

YES I have done this in a major Asian Airline, when my support F/O was being destroyed, tough afternoon for a while with the DFO Training, who supported me in the result.

This particular "trainer" when asked a question stated, "questions from you indicate a lack of knowlege" which should be a classic for the record.

Non of my comments should be taken to reflect on the unfortunate people at the Air North accident, we all await the full report and whatever changes may flow from that.

Stay safe

:ok:

[downwind]

From my point of view herein lies the 2 problems;

In Australia we just issue training approval to CAR 217/RPT organisations to easy, in JAR land one must do a full course to become a "TRI" and must pass a instructional abilitys assesment in the sim aswell to prove they can impart knowledge. In Oz all CASA needs for a training pilot is the hours stated by the ops manual and the tick from the flight standards manager or chief pilot. We really need to get in line with other ICAO regulators around the World, training is REALLY important! As for the sim's it should be a flat rule ANY RPT organisation be it greater or less than 5700kgs MUST use a sim (even any organisation other than RPT that operates a sophistacted a/c should also compulsury use a sim aswell) end of story and if the operator can't afford the cost of flightsafety, simcom etc.. they shouldn't be in business, an accident will cost you reputation, insurance etc.... I think it comes down to how much the boss of the company want's to spend. my 2 cents worth.

[MUNT]

" Once upon a time there was no choice as Sims for many aircraft were not available."

But that was then, this is now. This technology has been available for far too long, and the risks of this training have been known for even longer. Why why why are we allowed to conduct EFATO training at low level in the aircraft?! How tragic this reactive industry continues to be.

[Cycling Fish]

... Yes, there is a risk, however I suggest that good training techniques, good planning in conducting the sequences and appropriate briefings are all good mitigators against the identified risks. ...

Sorry Triadic, but that is just bollocks.
As training accidents happened on large aircraft at a rate significantly higher compared to line operations simulators became an international requirement many decades ago. Large aircraft training accidents have killed some of the best and brightest training captains and experienced line crews, regardless of their pre-sortie planning and briefings.
Look at the purchase/operating costs of a modern simulator - not really different from the costs of the aircraft it models (and with not much chance to have 300 fare paying bums seated behind the crew). Airlines and regulators know that that enormous expenditure of a new 747 simulator is money better spent than using any company 747 that is between revenue flights to conduct crew training.
Very simple risk management - all large aircraft training in a simulator, no debate, no waivers, no dispensations. If the company can't afford simulator training, then they should not be operating.

[LeadSled]

Folks,
Not mentioned here is the fidelity of the simulators, not just the IRE/TREs by whatever regional or operator name.

With major airlines and their simulator sections, this is not usually a major problem, but in my opinion, it is a problem where smaller aircraft are concerned.

It can also be a problem in "simulator centers" that serve a number of airlines. Commercial pressure militates against the ideal tailored training programs, tending towards the lowest common denominator and lowest cost, particularly where pilots are footing the bill.

Part of the CASA problem is that it is doubtful that their compliance staff have adequate combination's of training and experience for the fidelity checking of simulators.

In a similar vein, when an adequate simulator is not available, there seems to be a propensity to approve part task trainers beyond their reasonable limits. Indeed, some approvals have pushed the limits to qualify under Part 60 as a simulator at all, let alone a simulator really suitable for endorsement training.

On the subject of instructors, the task of eliminating personalities from the task is a close to impossible one, and it takes a rare boss of training or exceptional Chief Pilot to manage such problems. Accepting, of course, that he or she is not the Chief Offender.

There is room for huge improvement in the selection and training of IRE/TREs in Australia, at all levels of air transport operations.

Tootle pip!!

[barleyhi]

Wonder how CASA would view a 217 org doing engine failures in the circuit at night in a metro?

I thought we had learned from experience, but obviously not.

Why isn't the regulator doing its job and stopping this madness?

[Icarus2001]

Why isn't the regulator doing its job and stopping this madness? Are YOU doing YOUR JOB and reporting it to CASA?

Nothing personal barleyhi but I get very tired of the whining of people who are not prepared to DO something about it.

Write to CASA anonymously.

Call CASA anonymously.

Report it to the ATSB.

If you feel strongly about it do something about it.

[john_tullamarine]

Wonder how CASA would view a 217 org doing engine failures in the circuit at night in a metro?

That sort of thing has been going on forever when circumstances conspire. For instance, my first day failure practice on the Electra was on my first renewal ... the entire endorsement program had been done for the group at night to suit aircraft availability. I won't bother listing all the other rules we broke as well ... whether good or bad the job got done.

[remoak]

It's easier at night, you can't see the ground rushing up to smite you from some very strange angles... :}:}

[barleyhi]

Icasus2001

Already done

awaiting official response!

[av8trflying]

The report was released today.

Just a quick grab:

Contributing safety factors
• The pilot in command initiated a simulated left engine failure just after becoming airborne and at a speed that did not allow adequate margin for error.
• The pilot in command simulated a failure of the left engine by selecting flight idle instead of zero thrust, thereby simulating a simultaneous failure of the left engine and its propeller autofeather system, instead of a failure of the engine alone.
• The pilot under check operated the aircraft at a speed and attitude (bank angle) that when uncorrected, resulted in a loss of control.
• The pilot under check increased his workload by increasing torque on the right engine and selecting the yaw damper.
• The pilot in command probably became preoccupied and did not abandon the simulated engine failure after the heading and speed tolerance for the manoeuvre were exceeded and before control of the aircraft was lost.

Discuss

[john_tullamarine]

Final Report:

Investigation: AO-2010-019 - Loss of control - Embraer S.A. EMB-120ER Brasilia, VH-ANB, Darwin Airport, Northern Territory, 22 March 2010 (http://www.atsb.gov.au/publications/investigation_reports/2010/aair/ao-2010-019.aspx)


Jesus wept.

[rioncentu]

All other issues aside, the report and in particular the animation shows how quicly things can go wrong.

I have never flown anything other than a single so have no appreciation for assymetic training. But I am shocked to see how litle time elapsed between the flight idle and the aircraft rolling onto its back :sad:

Nasty indeed.

[Icarus2001]

There is a short movie (avi) that is very sobering. I spent years as a ME instructor, simulating engine failures after take-off, as required in the syllabus. I do not miss that part of the job one little bit.

[FGD135]

Gung ho checkies.

Very few of them appreciate just how dicey these exercises are. This checkie learned this, but with only a few seconds of his life left.

Most of them would be blissfully ignorant of the fact that more accidents happen in assymetric training than real assymetric emergencies.

[rocket66]

A wise old instructor in ME training said to me once that accidents, particularly with EFATO's occur through errors in conducting drills with haste. This may not be the case with turbines as my twin time is in pistons.

Ofcourse the actions must be prompt but not instant, I wonder how many accidents can be attributed to these kinds reactions??


rocket

[FRQ Charlie Bravo]

Very very sobering.

At the risk of sounding ignorant can I ask a very basic question of the more experienced pilots reading this? Can I assume that in a nutshell the two biggest errors here were:


Pitching to allow the aircraft to decrease below Red Line (or was Red Line not applicable due to the double failure including the feathering system?)
Not reducing the power on the good engine when direction could not be maintained.

Man, less than 22 seconds between initiating the simulated failure and being unrecoverable, that is damn sobering.

FRQ CB

[Jabawocky]

FRQ

I think the biggest mistake was not advancing the power lever when it started going pear shaped. But the power control on the right and not keeping the nose down seemed to be the start of it for sure.

FGD has a point too, knowing Shane and his family, gung ho is not what I would expect at all, maybe he was this day, but if I know the folk (him and his family) as well as anyone I doubt it was significant. More likely he had a belief the very experienced pilot being checked would not make a mess of it. Only a couple of seconds from belief-non belief - rolled on ya back and dead.

Reading how hard they are to control in a sim, the heavy control forces, and when you know what is coming and why you are doing the experiment, that makes for eye opening reading too.

Very sad event.:sad:

[Wally Mk2]

Nasty business this is.VMCA is something that should be avoided at all costs.
Notice in the animated sim that the rudder was not held at full deflection all the time especially when it started to roll on it's back. AS slowly decayed.The primary instrument to watch in these events apart from keeping wings reasonably level is airspeed. Airspeed is everything. You can go off course a fair bit and even lose a little Alt but losing AS & it's game over full stop! If you have to sacrifice anything make it Alt even if yr down at fence height a wings level crash is far more survivable than spinning in due going beyond VMCA.
I did many renewals in the old Beech 'till we got an old Sim to use. Man was that an eye opener! Old heap of junk Sim it was/is but it taught you to fly the numbers & had you as sharp as a razor blade in the end:ok:


Wmk2

[compressor stall]

I've just had a quick flick thru, but my take on the major issues the lead them into the trap (besides the culture of not doing itin the sim) are:

Checkie pulls per lever too far back, disabling autofeather and increasing actual min control speed. 25.149 from memory talks about vmc being certified with auto feather.

Checkee pull nose up too high. Speed loss. Puts in correct rudder, but not enough due to more adverse yawing than normal Puts aileron the correct way, but not enough and fails to stop increasing bank the wrong way (coming from the aforementioned yaw), further increasing actual min control speed

Aircraft gets towards the actual min control speed quickly which is now much higher than the normal 97 given the above (and this possibly caught the checkie out) and it's all over.

May we all learn from this.

RIP.

[Sarcs]

Very sobering!:( So what has happened to the 'mandatory sim' NPRM, has it been shelved till we have another EFATO training accident?:ugh::ugh:

[Algie]

In October 1954 TAA lost a Viscount (VH-TVA) on a training mission at Mangalore. Three pilots died. VMCA was at the core of this.

PROBABLE CAUSE: "An error of judgement on the part of the pilot-in-command in that he took the aircraft into the air at a speed below the minimum control speed....

They didn't have simulators of adequate fidelity then, but that was nearly 60 years ago. I have no idea exactly how many pilots have died in engine-out training since but it is not a small number I am sure.

The sooner this activity takes place where it can be done safely, that is in the simulator only, the better.

[Falling Leaf]

Very sobering! So what has happened to the 'mandatory sim' NPRM, has it been shelved till we have another EFATO training accident?

Sarcs, I raised that question late last year on a separate forum and no-one here knew anything. I quick search of the CASA website and all the literature points to a release of the CAO mid last year...:rolleyes:

[john_tullamarine]

One of the factors (in this case with a static departure) so pointedly obvious from the ATSB's animation is the typical small spread of IAS between "still under control" and "lost it" - it can all happen in the space of several knots and can be very dramatic as shown in the animation.

This phenomenon ought to be in the forefront of everyone's mind when playing in the asymmetric sandpit at or near the real Vmc for the day.

It brings a tear to the eye to recall a fatal (in which I was involved subsequently) which was a near mirror image to the present flight path - while the precipitating circumstances differed, the sequence and results were the same (albeit with a full load of passengers). That particular Type was not quite as dramatic as the present case, exhibiting a significant steady yaw prior to departure .. but the end result was the same.

At the expense of repeating oneself, Vmc is test pilot territory and one ought to maintain a comfortably wide margin from it for routine training operations.

[RENURPP]

Checkie pulls per lever too far back, disabling autofeather and increasing actual min control speed. 25.149 from memory talks about vmc being certified with auto feather. It's been over a decade since I have flown a turbo prop and that was a Dash not the E120, however I suspect the auto feather system would be similar to the Dash. (same engine prop combo as the Dash 100)
The auto feather isn't activated when simulating an engine failure by moving the thrust lever.
There were other requirements to make it auto feather, and I can't recall what they were. So the way I read it, the check pilot reduced the thrust below the zero thrust setting which creates extra drag and isn't an accurate simulation of auto feather, which in turn increases VMCa.

[Sarcs]

I raised that question late last year on a separate forum and no-one here knew anything. I quick search of the CASA website and all the literature points to a release of the CAO mid last year...:rolleyes:

Have gone through the relevant CAOs (CAO 40.0,82.0) and the Consultation Updates 2011 page :Civil Aviation Safety Authority - Consultation updates archives (http://www.casa.gov.au/newrules/changes/index.asp?session=2120784344&pc=PC_93263&year=2011) and cannot find anything beyond the NPRM, so wtf??:confused: Anyway if anyone can enlighten us it would be much appreciated!!:ugh:

[FGD135]

For a "real" view of what the EMB120 would have looked like, take a look at this video:

This was a Queen Air in the Philippines, only a few months ago, that also experienced a loss of power on the port engine. Hard to tell from the video, but it appears the prop was not feathered.

Like the EMB120 animation, there is a large amount of left bank immediately before the LOC.

The flight path of the Queen Air is almost identical to the EMB120. The result was identical.

Beechcraft Queen Air Stall and Crash - YouTube
(http://www.youtube.com/watch?v=vTQwkKameLg)

[compressor stall]

Compounding the tragedy is that it's textbook.

There are few new ways to die in aviation; someone's almost always succumbed to the same errors before.

[Blue Sky Baron]

Something that I noticed on the animation that does not make sense to me.
When stationary prior to take-off the asi is reading 30kts, the wind according to the report was 5kts. Can somebody explain this to me?

Could the asi have been overreading?

BSB

[Servo]

BSB, it want overeading. It was the minimum indicated airspeed as such on the indicator (actually is 40).CAIS or Calibrated IAS. OR

A FDR channel "error" brought over into the animation.

[john_tullamarine]

Like the EMB120 animation, there is a large amount of left bank immediately before the LOC

Unless the AFM says different, one can presume that the book Vmca is based on 5 degrees favourable bank for any conventional multi.

Realworld Vmc ramps up rapidly (and not linearly) as bank reduces and then goes the "wrong" way. The departure can be much faster than that arising from just letting the speed slowly come back trying to maintain height.

Include both reducing speed and bank going away from 5 degrees favourable .. and one is in for a very rapid and unpleasant roller coaster ride ... albeit only for a very short time ...

Back near Vmc, one pegs 5 degrees favourable bank like one's life depends on it .. which very well may be the case.

If that means a concurrent descent, so be it .. better to belly in right way up than corkscrew into the ground, upside down nose first ... and, if caught out in the situation and faced with a departure, it may be necessary to reduce thrust on the operating motor(s) to reduce Vmc .. allowing control if not performance.

[LeadSled]

Checkee pull nose up too high. Speed loss.

We still have FOIs, and ATOs and instructors under their influence demanding that the nose be pulled up to reduce to V2, if the failure happens at a speed greater than V2 ---- despite this dubious practice being abandoned in heavy aircraft training many years ago ----- but in Australia "compliance is all", gotta do what the CAO says.

In other threads, we still have "experts" (Xsperts) advocating "simulating" engine failures by chopping the mixture in pistons, or turning the fuel off.

Just in the last three days, I was talking to a quite well known instructor/ATO ---- who had little or no understanding of the changes of Vmca, depending on the bank angle.

I guess we will continue with a steady stream of fatalities in EFATO training, until we catch up with the rest of the world ----- and teach commonsense training techniques, and not blind "compliance".

Tootle pip!!

PS: Re. "compliance", a former Darwin FOI is now Bankstown based.

[Sarcs]

Small but relevant column on Australian Aviation website:ok::

Airnorth crash highlights importance of simulators — ATSB | Australian Aviation Magazine (http://australianaviation.com.au/2012/02/airnorth-crash-highlights-importance-of-simulators-atsb/)

PS: Re. "compliance", a former Darwin FOI is now Bankstown based.

Not the ex-seneca FO from China Southern, he'll be re-writing the AGK syllabus next!:ugh::{

[4dogs]

Vmca is a static speed. It is established in testing with asymmetric power/thrust set by incremental decreases in speed until one of the limiting parameters is met.

Because it is static and determined from a higher initial speed, it has some direct relevance to the Queenair video of slowly bleeding off the speed until LOC occurs. Well and good.

However, there is no element that accounts for sudden engine failure, slow rudder reaction or existing bank angle. The speed at which one of the limiting parameters will be met in the dynamic case will be much higher than the published static figure. There may be little margin, if any, between the target V2 and the dynamic Vmin if you have a sudden failure just after liftoff or at the start of a go-around. And in those cases, the priority is on control before climb.

The propeller related issues of loss of blown lift and discing exacerbate the dynamic issues substantially - I nearly lost a Conquest some 12-14 knots above the published Vmca during a practice engine failure in the GA, despite quite minimal reaction time as I saw the initiation begin. It seemed to take forever for the full rudder and full aileron to stop the roll and yaw, let alone bring it back to a sensible place.

JT: I seem to remember that, while certification standards limit the bank angle to "no greater than 5 degrees", the optimum is around 3 degrees.

And as for the good old V2 issue: it is a target speed from below (ie when accelerating), it is not the best anything (just the lowest speed at which the OEM can meet the minimum certification gradient) and, if you have already got it, V2+10 to V2+15 gives a much better gradient.

Stay Alive,

[MakeItHappenCaptain]

And to add to that, it (Vmca) is interpolated from LOC events at higher altitudes because no-one is dumb enough to intentionally find out what it is at low altitude.:E

[The Green Goblin]

And as for the good old V2 issue: it is a target speed from below (ie when accelerating), it is not the best anything (just the lowest speed at which the OEM can meet the minimum certification gradient) and, if you have already got it, V2+10 to V2+15 gives a much better gradient.

This got me into a heated position with a check captain during a cyclic check.

The engine was failed at about V2 + 15 (+/- about 5 knots). I slowed the aircraft to VFS (VySE) which was in this particular aircraft V2 + 10, and maintained it. The FO started calling 'speed'. I replied 'checked'. Once through AA the checkie paused the sim and told me that he wanted to see me maintain V2.

I told him that I would only maintain V2 if I was slower than it, and needed to accelerate to achieve it. If I were faster than V2 I would maintain that speed up to VFS (VySE) and if I were faster than VFS, I'd reduce to VFS.

Well this didn't go down to well. I was subsequently berated and told that I was required to maintain V2 until AA as this was the certification requirements of 20.7.1b. I replied that V2 was the TOSS, not a target speed for climb. I.e the minimum speed you could safely maintain to remain in control of the aircraft. You'd be daft to slow to V2 if you already had a margin of speed above it and a positive climb gradient

Tuns out I was right.......but I had to take some heat from it.

[betaman]

This got me into a heated position with a check captain during a cyclic check.

The engine was failed at about V2 + 15 (+/- about 5 knots). I slowed the aircraft to VFS (VySE) which was in this particular aircraft V2 + 10, and maintained it. The FO started calling 'speed'. I replied 'checked'. Once through AA the checkie paused the sim and told me that he wanted to see me maintain V2.

I told him that I would only maintain V2 if I was slower than it, and needed to accelerate to achieve it. If I were faster than V2 I would maintain that speed up to VFS (VySE) and if I were faster than VFS, I'd reduce to VFS.

Well this didn't go down to well. I was subsequently berated and told that I was required to maintain V2 until AA as this was the certification requirements of 20.7.1b. I replied that V2 was the TOSS, not a target speed for climb. I.e the minimum speed you could safely maintain to remain in control of the aircraft. You'd be daft to slow to V2 if you already had a margin of speed above it and a positive climb gradient

Tuns out I was right.......but I had to take some heat from it.

Interesting theory GG, how do you go passing an IRT or prof check doing that?

I replied that V2 was the TOSS, not a target speed for climb.
V2 means the initial climb out speed which is not less than the take-off
safety speed, it is not TOSS!!

Unfortunatley I am with your checkie on this one.

[Mach E Avelli]

Green Goblin's take on it is exactly the same as mine, and what I would have done if the engine quit at a speed above V2. Mr Boeing says if you are still in the second segment climb and already have speed greater than V2 when an engine quits, maintain that speed to the usual acceleration height etc etc. I don't have the manual with me, but seem to recall anything up to V2 + 15 is OK, assuming you already have that speed at time of failure. If you are faster, slowly come back to V2+15, by delaying the reduction of pitch (i.e. don't increase pitch just to get a lower speed).
What about 'improved climb' graphs and the performance benefits of climbing out above V2 min? V2 min is indeed sacred, but only if you haven't yet got it, you must get to it to have any guarantee of climb performance with an engine out, and of course to provide margin above Vmca. Unless the failure is introduced at V1 or at latest Vr, chances are the aircraft will be through V2 by the time the effects of a failure kick in. If you are already above V2, you can and usually should stay with what you have.
Engine failures in training should be introduced at various speeds - not just V1 or Vr - to reinforce this allowable flexibility. When training in real aircraft (as opposed to simulators) appropriate buffers should be built in - like assuming higher weights and V speeds for those higher weights.

[ManillaChillaDilla]

Guys, at the end of the day take the hypothetical plumb from your mouths and take a minute to reflect on the fact that the two aviators involved were, believe it or not, just like you.

How about a bit of respect. Does an extended net postmortem achive anything?

This industry has definately, definately changed.

Moderators?

[The Green Goblin]

Quote:
This got me into a heated position with a check captain during a cyclic check.

The engine was failed at about V2 + 15 (+/- about 5 knots). I slowed the aircraft to VFS (VySE) which was in this particular aircraft V2 + 10, and maintained it. The FO started calling 'speed'. I replied 'checked'. Once through AA the checkie paused the sim and told me that he wanted to see me maintain V2.

I told him that I would only maintain V2 if I was slower than it, and needed to accelerate to achieve it. If I were faster than V2 I would maintain that speed up to VFS (VySE) and if I were faster than VFS, I'd reduce to VFS.

Well this didn't go down to well. I was subsequently berated and told that I was required to maintain V2 until AA as this was the certification requirements of 20.7.1b. I replied that V2 was the TOSS, not a target speed for climb. I.e the minimum speed you could safely maintain to remain in control of the aircraft. You'd be daft to slow to V2 if you already had a margin of speed above it and a positive climb gradient

Tuns out I was right.......but I had to take some heat from it.
Interesting theory GG, how do you go passing an IRT or prof check doing that?

Quote:
I replied that V2 was the TOSS, not a target speed for climb.
V2 means the initial climb out speed which is not less than the take-off
safety speed, it is not TOSS!!

Unfortunatley I am with your checkie on this one.

The checkie no longer works there (neither do I), the operations manual was modified to reflect the above.

Mr Boeing says if you are still in the second segment climb and already have speed greater than V2 when an engine quits, maintain that speed to the usual acceleration height etc etc.

You'll also find this in mr Airbus' literature

:ok:

[LeadSled]

Betaman,
With all due respect, your reply typifies what is wrong with the "compliance" approach to training and checking.

I am reminded of the vehement opposition of the AFAP, at the time, to offset tracking. That offset tracking would prevent collisions in the event of all too common ATC mistakes, was not in dispute.

The AFAP opposition was entirely based on the CAO detailing tracking standards, and the rather stupid argument that, if a pilot was offset tracking, he was not "complying" with the CAO.

Conceptually, The Green Goblin is spot on , but you want to haggle with definitions, when he wants to fly his aircraft in accordance with the AFM ----- which is also a legal requirement, so I'll see your CAO, and raise you a regulation, CAR 138 ---- non-compliance with which is a strict liability offense with up to a 50 point penalty.

What The GG described would, I am willing to bet,be in conformity with the AFM and the manufacturer's training manual for his aircraft.

However, far more important is the fact, obviously unknown to you (or GG's check pilot) that we dropped pulling the nose up to get back to V2, after the American Airlines DC-10 loss at Chicago, many years ago.

Obviously, minimum climb gradients must be achieved at the nominated V2, but the performance of most transport aircraft, these days, will meet CAO 20.7.1b at a speed anywhere between V2 and V2+25 or more, at the chosen T/O flap setting.

The whole lesson of Chicago was that, in the event of Engine Fire, Severe Damage or Separation, you don't reduce speed or change configuration until you have a damned good idea of the situation and possible outcome.

In the Chicago DC-10 accident, the aircraft was controllable at V2+10, the pilot flying reduced to V2, and everybody died.

As this accident happened something like 30 years ago, and all the Boeing and Douglas ( and, I think, Lockheed) AFMs were amended as a result of NTSB recommendations, taken up by the FAA ----- and very promptly actioned, I am pleased to say, by Qantas, which was not fazed by the "imperative of compliance", at the cost of potentially losing an aircraft.

As a very wise former Director of Aviation Safety at CASA (Leroy Keith) once said:

"A compliant organisation is not necessarily a safe organization , a non-compliant organisation is not necessarily an un-safe organisation".

The subtlety of this view ( particularly given the shambolic state of regulation and standards in Australia) is clearly lost on all too many in the Australian aviation industry, within and without CASA.

Tootle pip!!

[john_tullamarine]

Some observations, if I may ...


demanding that the nose be pulled up to reduce to V2

archaic thinking .. as others have observed


Vmca is a static speed ... there is no element that accounts for sudden engine failure, slow rudder reaction or existing bank angle.

Not quite the case.

For instance, current FAR 25 Vmca test requirements can be reviewed at AC 25-7B (http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2025-7B%20Chg%201.pdf) starting page 102.

The usual Vmca workup starts with the static Vmca (cf the typical pilot Vmca demonstration exercise). After this figure is determined, dynamic Vmca checks are made to ensure that the final figure published in the AFM covers both cases.


The speed at which one of the limiting parameters will be met in the dynamic case will be much higher than the published static figure

Not necessarily so but is covered in the AFM figure as above.


or at the start of a go-around

Different figure to that for takeoff and is established during certification


It seemed to take forever for the full rudder and full aileron to stop the roll and yaw, let alone bring it back to a sensible place.

This is a common observation unless the pilot has been through the wringer in sim training with the result that reactions are instinctive.

For instance, I recall (quite fondly) one endorsement crew (initial command ex 744 F/O and intake F/O) on the 732 during a contract training engagement many years ago.

The initial command chap hadn't ever really got on top of takeoff engine failures and, initially, was very underconfident. Not a good situation for that stage of his career. We fixed that problem late one night when (on the sly) we took one programmed session and hammered failures .. the next session was a spare and the techs let us continue on so the time ended up totalling around 6 hours as I recall.

To cut a long story short we made extensive use of freeze and reposition to concentrate on the difficult bits for both guys, working our way back to min weight, aft CG, min speed schedule takeoffs with the failure (a very impressive modelling of an historical large bird impact FDR trace - ie catastrophic seizure). By the end of the session, both guys could handle the failure with continued takeoff tracking the opposite end LLZ .. just about with their eyes closed. They toddled off home dead tired but with very large swelled heads and the rest of the endorsement program went pretty smoothly ...

As this particular operator made very extensive use of overspeed takeoffs and, as far as I could determine, only used low speed schedules for ferry flights from one coastal aerodrome .. and did all their sim training for the overspeed case, my contract colleagues and I were rather concerned for obvious reasons.

During the occasional checking/renewal sessions, I took to introducing the lowspeed case in play time .. where the pilots were prepared to have a looksee at the problem.

In just about every case, those who had a go at the critical case .. cold ... did the Braz sequence .. the sim, of course, was frozen shortly after the departure. All were able to get on top of the failure with a bit of explanation and several practice runs.

The point was the pilot responses had to be instinctive, near instantaneous, and quite aggressive to survive. I have no objective information as to just how the sim fidelity was for that exercise .. but it sure appeared realistic regardless of from which seat one saw it.

I think you did very well to survive your encounter, good sir.


standards limit the bank angle to "no greater than 5 degrees", the optimum is around 3 degrees

Static Vmca Standards impose a maximum favourable bank of 5 degrees. Given that the OEM would like to get the lowest Vmca possible .. as Vmca limits other certification considerations, a fence needs to be put around the paddock to maintain a level playing field. In addition, too much bank increases sideslip and, for such an exercise, too much of a good thing can be rather bad ...

Once the failure is sorted out and the aircraft gets to a sensible speed (somewhat higher than Vmca) the pilot can start worrying more about performance than control. It appears reasonably general, that optimum bank for climb performance is around 2-3 degrees regardless of Type. The only caveat is for some AH systems which can't tolerate steady small bank angles so, in general, the optimum is traded for the simpler by sacrificing a little performance and climbing wings level. Much easier for the pilot and the result is not all that different.


if you have already got it, V2+10 to V2+15 gives a much better gradient

The climb characteristic curve is a bit like an upturned cup .. with V2min well away from the top. Overspeed V2 provides a better climb gradient. Generally the top of the curve will be a moderate margin above V2min. Looking at routine overspeed schedules, the limit generally runs to V2min plus 20-30 to keep a check on ridiculous runway deltas.


Does an extended net postmortem achive anything?

If a bit of knowledge saves a crew next time .. I'd say that's a positive ... wouldn't you ?


we dropped pulling the nose up to get back to V2, after the American Airlines DC-10 loss at Chicago, many years ago.

Indeed .. and essential reading at NTSB AAR79-17 (http://www.airdisaster.com/reports/ntsb/AAR79-17.pdf). Although this mishap involved an asymmetric stall, the Industry recognised it as a wakeup call regarding pilot techniques during takeoff failures.

[The Green Goblin]

V speeds - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/V_speeds)

Betaman and the like, I hope you learnt something tonight.

For the record, V2 is a TOSS, nothing more. It's not a magic speed that will fix all ones worries in an asymmetric situation. It's just the minimum speed you can fly to achieve certified climb gradients.

Which is why it's called the take of safety speed :ok:

[thorn bird]

John & greenie,
you guys are perhaps examples of "trainers" against "checkers".
Trainers teach...checkers just check and that is why some of this
"Bullsh...t" gets entrenched into our system.
It starts in GA where half qualified FOI's enforce their "opinions",
and massage their ego's, by forcing this sort of stuff into CAR 217 organisations. You cannot argue with them or reason with them, they are always "Right". A small CAR 217 organisation simply dosnt have the clout to pull them up..."comply with what I say" or you lose your accreditation, or suddenly become a " A not fit and proper person".
I failed a check ride for maintaining V2+10 instead of V2, have also been instructed that Full stalls must be conducted in a T tail jet, and stability augumentation must be turned off to practice stalling.
Actually I'm amazed more good pilots havnt been killed by these lunatics in charge of the asylum, and leadie am I right in that the BK FOI was the one the Skull reinstated after getting thrown out of Darwin?

[Sarcs]

Absolutely spot on thorn bird!:ok: Except for this...It starts in GA where half qualified FOI's enforce their "opinions",
....I think your being over generous!:yuk: Especially when it comes to this individual: and leadie am I right in that the BK FOI was the one the Skull reinstated after getting thrown out of Darwin?

[john_tullamarine]

I failed a check ride for maintaining V2+10 instead of V2,

I guess that, sometimes, one has to play the game. However, the fault probably lay with the operator (and, perhaps, OEM) for not generating a more liberal SOP in the Ops Manual.


have also been instructed that Full stalls must be conducted in a T tail jet

Stall protocols are another major concern when it comes to the operational standards side of the table not always having much of an idea of what the certification folks did in the first place.

The certification flight test standards have varied over the years so that aircraft A and aircraft B might well have had different techniques applied in the stall certification.

One example comes to mind - a well-known flight test organisation used to use a particular light twin for TP training. This particular Model was certificated by approach to the stall only, rather than pulling into the developed stall.

Apparently, during one course, a USAF trainee proposed that it might be interesting to check out the developed stall .. whereupon the aircraft flicked into an inverted spin.

Food for thought ?

Lesson is .. before making it up on the run, do some homework on the certification standards and techniques relevant to the aircraft via TCDS, Design Standards, ACs, etc.


stability augumentation must be turned off to practice stalling.

I presume we are talking SAS stuff here ? Given that the usual reason for SAS is to fix a deficient stability characteristic found during certification testing, AFM admonitions MUST be observed lest the pilots find themselves in a pickle beyond their knowledge limits.

For instance, the same flight test organisation used to use a well-known (different) twin for training. This particular aircraft incorporated a SAS to fix a very undesirable longitudinal static stability problem during the missed approach.

Consider the situation with the system deactivated .. you, as pilot, initiate an overshoot (not too different from stall recovery when you run up the thrust at the appropriate time) and, with an unintended reduction in speed, you find that you now have a runaway speed reduction unless you push forward aggressively - the reverse of what you expect normally with a stable aircraft where you have to put in a pull force to fly slower than trim speed.

Again, know what the story is for the aircraft prior to making it up on the run ...

[004wercras]

Actually I'm amazed more good pilots havnt been killed by these lunatics in charge of the asylum, and leadie am I right in that the BK FOI was the one the Skull reinstated after getting thrown out of Darwin?

This individual was almost certainly one of the “holes” in the “reason model” that was causal to this tragic accident.

Fortunately several Operators in DN voiced their concerns about this individual and he was subsequently transferred and some semblance of sanity returned.

Unfortunately a couple of our Checkies (one of which ended up becoming our CP) was tainted by his mantra, some of which defied all commonsense and the laws of physics .

Examples were-
(a) Sudden and vicious V1 cuts just as the aircraft was rotating (and they wondered why we were having multiple/un-explained torque rollbacks across the fleet);
(b) low level (200-300’ overwater or on takeoff) stickshaker climbs;
(c) sudden and un-warned emergency descents with full crew onboard;
(d) low level (200-300’ overwater) steep turns with foggles on and sometimes with full crew onboard ( one of the checkies said that this was a regulator requirement, even though it was contrary to SOPs and company Ops manuals);
(e) demonstrating x-wind technique by keeping the down-wind mains in the air for an extended amount of time (FDR recorded 17.5 seconds), this manoeuvre nearly had the aircraft departing the runway and the sudden hard braking resulted in a skidmark over 100m long with the result that two main tyres were destroyed (this incident led to the checkie losing his approval and being demoted). The list of examples is by no means exhaustive.

All those operators in the Sydney basin beware of this individual, if he his assigned to oversee your ops and you value your business and the safety of your employees’ then demand to have someone else!

[framer]

How about a bit of respect. Does an extended net postmortem achive anything?



Well.... it's motivated me, in a different country, flying a different type, to get my books out and brush up on a few things so I guess the industry is a fraction safer. But I bet I'm not the only one.

[porch monkey]

And you'd be right, dude!

[Ex FSO GRIFFO]

I'm with you Mr Framer...

I don't fly 'every day', and I don't fly twins as regularly now.
I have been 'back to the books' for a few of these posts, to rejuvenate the grey matter a little.
A sim practice, or a good safe practice at a safe alt. I know would be a whole lot better, but.....we do what we are able to do....

Cheers:ok:

[betaman]

V speeds - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/V_speeds)

Betaman and the like, I hope you learnt something tonight.

For the record, V2 is a TOSS, nothing more. It's not a magic speed that will fix all ones worries in an asymmetric situation. It's just the minimum speed you can fly to achieve certified climb gradients.

Which is why it's called the take of safety speed http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/thumbs.gif

Ok GG, LS, et al,

Looks like I owe you an apology!

I have always used the 20.7.1b definition

"V2 means the initial climb out speed which is not less than the take-off safety speed;"

Which seems to imply that they are two different speeds.



But having blown the dust off the AFM of the last two turbo prop types I flew, my copy of Handling the big Jets & some old ATPL notes which quite plainly states that V2 is the TOSS.
Wish I could say that it was due to too many reds or stubbies but I was sober as judge, so yes I did learn or re learn something.




Incidently both AFM's don't mention anything about climbing at a speed higher than V2 but the current aircraft I fly does, so go figure.



Cheers

[compressor stall]

For those interested, there are a couple of iphone/ipad apps showing the FARs in a nice easy to navigate document that is also appropriately hyperlinked making regs that cross reference others simple. I know the stuff is free on the net, but the formatting does make such a difference to getting your head around some of the bits.

[The Green Goblin]

Glad we could help :cool:

Also good to see is someone who's mind is not a closed shop (like many in the industry).

Now it will become a frustrating exercise reducing your climb out speed to V2 to appease your checkie when you know it's a rediculous manuovre that could cause a loss of control for no reason other than ignorance.

Handling the big jets is pure gold.

[framer]

Also good to see is someone who's mind is not a closed shop (like many in the industry).

Spot on.It's a mark of maturity and character to wite a post like that. It used tbe the norm a decade or three ago, now....not so much.

[john_tullamarine]

Incidently both AFM's don't mention anything about climbing at a speed higher than V2 but the current aircraft I fly does, so go figure.

Probably a simple answer upon reflection -

(a) there is no imperative for the OEM to provide overspeed schedule data

(b) your turboprops, I guess, are short range machines (Dash, 340, and similar ?) so the presumption is that a lot of departures are from shorter runways where min speed schedules rule.. ie not much demand for overspeed schedules.

(c) jet ops typically involve longer runways at major aerodromes where the opportunity to squeeze a bit more payload out of a runway is significantly greater ergo more reason for overspeed scheduling


One very important point with increased V2 considerations which I don't recall seeing noted is - OEI, one should never attempt to increase V2 from a lower speed to get a better climb due to the distance penalty in the air - while the final climb will be better, the intermediate problem is that the aircraft will probably run under the planned NFP with obvious terrain clearance considerations.

The whole idea of the higher airspeed covers two situations -

(a) if the takeoff is planned with overspeed scheduled speeds, the higher V2 is targetted as part of the OEI takeoff

(b) if the initial takeoff didn't involve a failure, then the airspeed, in all likelihood, will be somewhat above V2 which puts you in a better part of the climb characteristic (gradient curve).

So, in the event of a post-V1 failure, hang on to whatever speed you end up with (after the failure is controlled) within a modest increment band (typically quoted as V2 to V2+20 or so) rather than pitching up to slow down to V2.

If, on the other hand, you are at V2+40, say, then, in the absence of general knowledge regarding your position on the climb characteristic, it is a better practice to pitch up slowly to come back within the AFM-cited overspeed range.

[Sarcs]

Without this diverging into a mixture vs closed throttle vs Flight idle vs zero thrust debate has anyone noticed the gradual decay of the quality of investigation reports coming out of the ATSB?

Besides the Hempel Inquest, where the ATSB appears to have abrogated all responsibility to investigate at all, the ATSB report into the Brasilia accident in Darwin is nothing short of totally spare in its conclusions!

There also appears to be no 'Safety Recommendations' generated from a training accident that I think we could have all learnt a lot more from.

Take a look at a couple of extracts from the report:


Terminology used in training and checking
The operator’s documentation did not contain any specific terminology for discontinuing a manoeuvre, but did provide clear instruction as to how control of an aircraft was to be changed between crew members.
To take over control from the pilot flying, or for the pilot flying to relinquish control to the other pilot in a multi-crew aircraft, very specific terminology was used. To avoid any confusion as to which pilot was manipulating the controls, the operator’s General Policy and Procedures Manual, section 4.7.2.2 Crew Communication - Handing Over and Taking Over stated:
The process of handing over control of the aircraft shall always be conducted in a positive manner. To minimise confusion or operational risk, the following terminology shall be used.
To assume control, the pilot monitoring shall call "taking over". To relinquish control, the pilot flying shall call "handing over".
Control of the aircraft cannot be handed over until the pilot monitoring has called "taking over"...
The term ‘disengage’ that was used by the PIC during this simulated engine failure was not standard phraseology. Other EMB-120 pilots reported that they had never heard the term ‘disengage’ used for any action other than deselecting the autopilot/yaw damper and had never heard it used to discontinue a manoeuvre.
They also reported that if a training or check pilot decided to discontinue a simulated engine failure procedure, they would expect that check pilot to restore power to the ‘failed’ engine. Alternately, if the training or check pilot wanted to assume control of the aircraft, they would expect to hear the term ‘taking over’.

Which is pretty basic stuff in a multi-crew aircraft....and then in regards to the Yaw Damper....

The operator’s flight operations manual for the EMB-120 stated that the yaw damper was not to be used for takeoff or landing, and that the minimum speed for its use during one engine inoperative (OEI) flight was 120 kts indicated airspeed (KIAS).

.....and then more in relation to the apparent Yaw Damper activation...

The use of the yaw damper during asymmetric flight was introduced to the simulator testing following consideration of the cockpit voice recording references to the PIC’s command ‘disengage’ and the pilot under check’s response, ‘yeah, disengaging’. It was assumed that the reference was to the yaw damper and not the autopilot because the chime that sounds when the autopilot was disengaged was not heard on the CVR recording. Additionally, the simulator instructor reported having previously observed pilots engage the yaw damper during simulated engine failures in the EMB-120 in response to pilots ‘overcontrolling’ rudder and aileron following a simulated engine failure.


All of the above is all good factual investigative methodology a lot of which points to a number of operational issues (company SOPs etc) and regulator oversight issues....right?? Wrong, take a look at the first paragraph of the ATSB conclusion.


No organisational or systemic issues that might adversely affect the future safety of aviation operations were identified as a result of this investigation.


Maybe this conclusion is a result of the regulator putting in place the Mandatory Simulator program and subsequent NPRM leading to the current NFRM, but does it excuse glossing over what was a particularly significant training accident event that, although tragic, we could all have learnt from!:=

ps ....and what gives with the no 'Safety Recommendations' issued!:ugh:

http://www.atsb.gov.au/media/3546615/ao-2010-019.pdf

[Kharon]

Look at the stellar job BASI did on the Seaview fatal.

Then look at the half hearted, puling effort ATSB made of Lockhart River.

Then read the pile of bollocks produced for Whyalla.

Compare the J* soft porn against the harsh fantasy of the Tigers tale.

Then read this provided by HMHB for the Hempel inquest.
Found the reference in the annual report
Civil Aviation Safety Authority - Stakeholder liaison (http://www.casa.gov.au/scripts/nc.dll?WCMS:STANDARD::pc=PC_93468)
Complementing activities under the MoU, in 2008–09 CASA established an Accident Liaison and Investigation Unit to manage the agencies’ day-to-day interaction. The unit provides a contact point for the ATSB, reviews all ATSB occurrence reports and prepares responses to ATSB recommendations, and identifies opportunities for aviation safety improvement.

CASA has also established an Accident Investigation Report Review Committee, chaired by the Deputy Director of Aviation Safety, to review and agree on the method of implementation of any formal recommendations from the ATSB.
Then, when you join up all the dots; call a taxi for the Minister - they are his watch dogs after all.

Abogate - ab·ro·gate tr.v. ab·ro·gat·ed, ab·ro·gat·ing, ab·ro·gates
To abolish, do away with, or annul, especially by authority.

[Centaurus]

has anyone noticed the gradual decay of the quality of investigation reports coming out of the ATSB?


I agree. Of course we are not privy to the original draft by the investigating team which when all put together without the benefit (?) of lawyer input is probably a lot clearer than after it has been sanitised.
With all sorts of litigation flashing around as a reult of a serious accident, is it any wonder that ATSB are very careful in how they word the final document.

[Slippery_Pete]

standards limit the bank angle to "no greater than 5 degrees", the optimum is around 3 degrees

4Dogs, JTs comments are correct on this.

You are infact talking about two completely different things.

One is an attempt to minimise Vmca.
The other is where the aircraft performance (ie rate of climb) is best.

They are two separate objectives. Vmca will, in nearly all aircraft, continue to DECREASE a little more as bank increases above 5 degrees towards 8-10 degrees. As JT said, this is not practical, so certification places a restriction on the manufacturers that Vmca can not be at more than 5 degrees angle of bank.

It is also important as people have said, that during certification, speed is slowly and in a very controlled manner reduced back onto Vmca. The current type I fly at a minimum speed takeoff, requires aggressive and sudden application of full rudder and 60-70% aileron during rotation. Once at the required pitch attitude, these can be reduced very slightly. This is in complete contrast to a nice, slow and controlled walk back into Vmca.

Vmca could be considered somewhat of an irrelevant speed in flight operations (important conceptually, of course). When was the last time you had a V1 cut, and rotated the aircraft into the air with 5 degrees angle of bank?

All this discussion about min speeds is all well and good, but not particularly relevant. The main causes IMHO were:
1. Should have been in a sim
2. Autofeather failure with a V1 cut is a ridiculous scenario to train for. How many times has this actually happened vs. how many people have been killed training for it? ABSOLUTE waste of time.
3. The checkie made some fundamental errors when it turned to :mad:.
a) He should have been trained by CASA to have a strict set of criteria (a maximum heading change, speed change, controllability change) upon which he terminated the exercise immediately by no method other than advancing the power lever of the failed engine.
b) He should have been trainined by CASA that in the event of pushing the "failed" power lever forward, if things were still not improving, that the live engine should have been pulled back to ensure directional control, even if this required a temporary loss of altitude.

Both crew most probably could have given quite a good rundown in the briefing room on what Vmca is, under what conditions it is certified, and what that speed was for their aircraft.

But that knowledge meant nothing when the exercise was not immediately terminated when it went pear shaped, and when the power on the live engine was INCREASED, not reduced.

Anyone CASA approves to complete ME aircraft training needs to be extensively trained and examined on the following before being let loose:
1. Be absolutely confident in their head which engine they are going to pull and what actions will be required
2. Guard the "wrong" rudder just prior to the failure to provide protection against incorrect rudder application
3. Have a STRICT set of SMALL tolerances, beyond which they commit themsleves to IMMEDIATE termination of the exercise
4. Where exercise termination is required, do this by immediately advancing the "failed" engine
5. Where this does not resolve the issue immediately, reduce the live engine power to ensure directional control (sometimes at the expense of altitude)
6. Immediately takeover control of the aircraft.

Another two (from all reports) nice guys of aviation who have paid the ultimate price because of archaic, 1960s training ideologies & methods.

[aussie027]

Slippery Pete,
Very well said.
Your comments re strict criteria for control of and termination of the exercise are spot on. That is what is required in all training scenarios but especially something as critical assym work at the very edge of the envelope and close to the ground.
Again doing so in the sim is best and safest in these TKOF scenarios.
As you say it is never worth dying for to practice some extremely unlikely scenario that out of hundreds of millions of TKOFs worldwide over decades an EXTREMELY small number of flights have ever experienced.

Also for everyone out there who has seen the variety of FAA definitions of V1 that have been published over the last 30yrs here is the best one I have seen that is most accurate and easiest to remember--

V1

"The speed at which the takeoff must be continued, if the abort has not already been commenced." :ok:

V1 is NOT the latest speed for a stop decision, V1 is a GO speed, the difference is significant and critical. The failure must be recognized and the decision made before V1.

I have the article explaining those statements in a file, if anyone wants to see it just pm me.

[Wally Mk2]

I've always found the V1 speed thingy a total croc! No one can actually read/nominate this defined exact number whilst hurtling down a rwy sheez our speedo's aren't calibrated to such an accurate figure anyway!
By the time yr eyes see the V1 speed reach the line in the sand, yr brain processes it sends the req'd message to yr voice box the recipient processes that sound via his/hers ears into usable info & then via their CPU (brain) for consideration yr almost at TOC!:-) It's an arbitrary figure.

Aussie's comments are spot on re V1's def.

For me once the speed V1 has been called it's too late to stop (theoretically anyway) you go unless it's unflyable & even then it's an unknown as to the extent of major damage.

Wmk2

[Mach E Avelli]

But better to go off the end of the runway at 20 knots than to get airborne at 100 knots+ and go splat from 200 ft.
In training, where you don't have the luxury of a simulator, schedule the MAXIMUM V1 that the runway or aircraft performance allows, regardless of the real V1 for the weight at the time. Then you have a nice fat buffer for the lower typical training weight.
Scheduling V1 min for actual training weight will put many aeroplanes too close to Vmca for comfort.
The check pilot can always simulate a heavier aircraft weight to align with the high V1 by judicious use of less than max T/O power. This provides a further safety buffer against Vmca.
In fact, scheduling V1 max is not entirely a silly philosophy wherever you have a runway that will allow it. The longer you stay glued to the ground the better, because that's the best place to have an emergency if you really must have one.
How many runways do we have that we use for training that are really so accelerate-stop limiting that we must use V1 min?

[Sarcs]

I think K has a point here, take a look at the Seaview report from about pg 44 onwards:

http://atsb.com.au/media/24362/aair199402804_001.pdf

BASI (as they were known then) kicked the regulator so many times (13 directly) that their noses would have left a trail of blood from the accident site to Lord Howe and back to Canberra....all without stepping outside the boundaries of their remit!:ok:

No wonder the metamorphosed CASA promptly circled the wagons, battened down the hatches and have been in seige mode ever since! :ugh:

[By George]

Interesting to see that some Airlines no longer call out "V1" anymore they call "Go". I'm sure Lufthansa is one and I think it's a good idea. V1 is called a decision speed by some which is not entirely correct.

[Kharon]

I find I am once again forced to read between the lines of an ATSB report. Technically it's spot on; for example, reading the time line analysis, there is a temptation to question the rudder v aileron input, however this is clearly resolved in the computer simulation graphics. Not having operated a Braz – there are a couple of points of interest which perhaps can be explained by someone who has.
Disengage ?? –could this refer to the Flight Director or is it the Yaw Damper ?. I note the AFM mentions –(paraphrased) FD Before take off (SET), expanded to PF select GA and check 7° pitch up; and, that the AP or YD may not be engaged during TOFF and LAND manoeuvres.

Has it been SOP for the PF to engage the YD as part of an EFATO or was this a recent innovation ?.

The V1, Vr and V2, V2 +10, etc. schedule. The AFM seems to be clear about the speed schedule and the acceleration to V2 +, then flaps up then Vfs (paraphrased). There appears to be a deliberate reduction from V2 + 4 (at – 23 seconds) to V2 (at -20.7 seconds). Is this a norm for the type or a new innovation ?.

Is the un monitored management of the OE, the over torque (124%) and the corresponding rudder/aileron excursions normal for the airborne exercise being conducted ?.

It is suggested by the ATSB final analysis that the BASI recommendations made after an investigation into the Flight Idle v Zero thrust (auto feather) scenario have been ignored. There is much documented proof that CASA have been enforcing 'black letter' CAO 40.1 requirements which conflict with both the AFM (see CAR 138) and a common sense approach to airborne EFATO exercises.

It is noteworthy that simulator based training had been recently introduced; and, conversely that Air North have safely, successfully conducted many 'in flight' simulated failures prior to the introduction of 'simulator' techniques. It is of concern that several things occurred which should give a check pilot the screaming heebie jeebies, airborne.

Perhaps we could ask of the ATSB to investigate 'in depth' the contributing factors to this situation occurring. We have the almost self evident facts of the accident, we have the why, but maybe it would be nice to know the wherefores.

P.S. Categorically not having a pot shot at the crew, the company or the simulator. Just seeking a satisfactory explanation of why and how this 'abnormal' chain of events occurred. If this was a new ME instructor and an initial twin conversion, perhaps this event may have occurred, but it wasn't – was it.

[Sarcs]

It is noteworthy that simulator based training had been recently introduced; and, conversely that Air North have safely, successfully conducted many 'in flight' simulated failures prior to the introduction of 'simulator' techniques. It is of concern that several things occurred which should give a check pilot the screaming heebie jeebies, airborne.

Perhaps we could ask of the ATSB to investigate 'in depth' the contributing factors to this situation occurring. We have the almost self evident facts of the accident, we have the why, but maybe it would be nice to know the wherefores.



A lot of what was covered in the ATSB report touched on the areas of operational concern and hinted to several differences in history where the Check Pilot had started to diverge from his 'norm'. This quote from page 54 of the report is significant:

Two of the pilots who were recently assessed by the PIC reported that he selected flight idle (zero torque) to simulate an engine failure after takeoff in their check flights. It was possible that the PIC had decided to deviate from the operator’s approved procedure in order to test the recognition by the candidate of the additional failure of the autofeather, before setting zero thrust.

However it isn't clear whether this 'divergence' from his 'norm' started after he had been to the simulator or before. If it was after then one may suggest that he was operating in a 'simulator induced complacency' manner i.e. it was proven that Flight idle (aircraft) or 'Autofeather Failed' engine failure (simulator) could be successfully recovered from while conducting a V1 cut.

This also appears to have been an area of concern for the regulator, as they used this accident as an example in Annex A of the NFRM for Mandatory Simulator, see here:


From CASA NFRM Mandatory Simulator training Annex A:

COMMENT 1.2
Some respondents proposed adding wording to allow training and checking to occur in the aircraft provided the exercise had been conducted by all pilots in a simulator in the preceding 12 months.
CASA Response
CASA is firmly of the view that where a qualified STD is available for aircraft of this size, this should be used for all training and checking activities. The ATSB has reported that the training captain of the aircraft involved in an accident in Darwin in March 2010 had undergone training and checking in a flight simulator, however the actions by the training captain in simulating an engine failure in the actual aircraft during the accident flight was not consistent with the training received during the simulator course. This suggests that doing one session of training and one check per year in an STD (with the subsequent session/check in an actual aircraft) does not satisfactorily address the risk of conducting non-normal exercises in an actual aircraft.



If the Check Captain was inducing this scenario (FI V1 cuts) prior to having gone to the simulator, whereas previously he always only induced a Zero Thrust EFATO scenario, then there must have been input from somewhere/someone to change him to suddenly start breaching the company T&C SOPs??

As 'K' suggests there has been many takes, ambiguity and debate..etc..etc..on the regulatory requirements of CAO 40.1.0:

There is much documented proof that CASA have been enforcing 'black letter' CAO 40.1 requirements which conflict with both the AFM (see CAR 138) and a common sense approach to airborne EFATO exercises.



Maybe there is an element of rogue FOI's, that lack the necessary industry experience, that insist on adhering to the letter of the law in CAO 40.1.0. Instead of applying practical safeguards and risk management to high risk training and checking scenarios!!

[john_tullamarine]

Vmca will, in nearly all aircraft, continue to DECREASE a little more as bank increases above 5 degrees towards 8-10 degrees

A LOT more. The nature of the beast is that

(a) for near wings level, Vmc varies sedately with a degree or two of bank

(b) the further we get away from wings level, the HIGHER the RATE at which Vmc varies with bank. Nothing sedate about it as the bank increases beyond 5 degrees. More importantly, if you are back near the real Vmc for the day (ie for 5 degrees) and you let the bank reduce or, worse, go the wrong way, the Vmc can ramp up VERY quickly and you might find yourself emulating the video linked a few posts ago.

When was the last time you had a V1 cut, and rotated the aircraft into the air with 5 degrees angle of bank?

However, if you are using a min speed schedule, especially if Vmca limited, and the configuration/conditions put you near to the real Vmc, then you had best make sure that you roll in the 5 degrees during the rotation flare ...


Mach E Avelli, who has been around for a LONG time and has a sound idea of what is what, provides good guidance in recommending the use of higher speed schedules within the RTOW ambit when departing at very light weights .. and not just for training sorties .. works the same way for line operations.

I would add that this is even more relevant in the case of a stiff crosswind takeoff .. why expose yourself to a potentially significant Vmcg consequence when, with a bit of lateral thinking, you can avoid it altogether ...

[sheppey]

The longer you stay glued to the ground the better, because that's the best place to have an emergency if you really must have one.

Interesting point of view which many will agree with. I guess we all have our personal opinions based often on personal experience.
I have always favoured a low V1 based on research papers that state most runway accidents are caused by a late abort when it was never necessary in the first place. A burst tyre is more likely at high speed than low speed and the general rule espoused by McDonnel Douglas aboout 30 years ago, was that it is safer to continue the take off from 15 knots below V1 rather than risk extended abort distance with a buggered tyre and associated brake loss that wheel. The statistical chances of hitting an obstacle after take off following engine failure after V1 are far less than the probability of a cocked up abort at high speed which is how some aircraft have crashed because of an over-run.

The higher the V1 the more the energy needed to stop with resultant hot brakes. Historically, overruns caused by an abort beyond V1 have occured because of indecision/uncertainty or even incompetency by the crew. If a late abort on a heavy weight take off occurs for whatever reason, there is the possibility of the brakes being beyond their energy limits and thus brake failure. For all these reasons this writer takes the view that a low VI if available, is a safer proposition in terms of the go decision rather than sweating out an unecessarily high V1 and the demonstrated dangers of a high speed abort. I would be much happier with a 20 knot spread between V1 and VR than having V1 =VR or maybe a couple of knots below.

[BPA]

Tend to agree that the standard of reports coming out of the ASTB is getting worse. Most reports these days a full of quotes etc about human factors from other sources and no real meat anymore. A lot of the reports they produce about incidents involving QF, Jetstar and Virgin are copies of the reports the safety departments from those airlines have produced ie they are letting the airlines do all the work and then take credit for it.

Have a read of some of reports the NSTB or the AAIB have produced such as the Q400 crash and they contain far more than just quotes on human factors and the like.

Perhaps it's time to start a new thread about the standard of the ATSB reports coming out.

[Mach E Avelli]

Sheppey what you say about a good split between V1 and Vr is sound advice if the runway is close to limiting for the weight i.e. accelerate-stop is critical. But at LIGHT weights - as in training or short-haul operations (which are more often landing-weight limited at destination) - there will usually be plenty of margin to allow V1 max for the runway to be scheduled, bearing in mind that it will accelerate very quickly and also stop more quickly because the weight is less than limiting for the runway length. Hence in distance terms, V1 even at 'max' will be reached much earlier than it would be at limiting weight, leaving proportionally more room to stop if need be.
I like the Lufthansa idea of dropping the term V1 in favour of the word 'go'.
One operator I worked with called V1 when 4 knots below actual V1, which also reinforced the idea that by V1 you had to continue.

[Flautist]

The whole "disengage" quote from the CVR is extremely confusing.
Engaging yaw damper or autopilot has never been a practice at Airnorth, and no-one has even contemplated it - no idea which other companies the CASA interviewed sim instructor was recalling when he stated that some pilots do it as it had nothing to do with Airnorth! We have no clue as to what the pilots involved were refering to or why.
The over-torque to 124% is also puzzling as there has always been a paranoia at Airnorth over even approaching the 20-second 110% torque limit. We also find it unexplainable how a boost up to 124% would be made for so many seconds, and without even a reflexive comment on spotting it and retarding the lever back to within limits.
The physics of the crash sequence are simple enough, but there are too many questions about what was actually happening, and why.

[Sarcs]

Flautist I believe your response further highlights the deficiencies in the investigation and the final report.

Other than the assumption by the ATSB investigator:


Quote:
The repeated command to ‘disengage’ suggested that the PIC was referring to a system under the control of the pilot under check, most likely the yaw damper.

Nowhere do they actually prove that the Yaw Damper was actuated and then 'disengaged'. It is also unstated about the obvious implications of having the Yaw Damper engaged, contrary to the AFOM.

If anyone has ever inadvertently taken off with a Yaw Damper engaged, while maybe conducting a touch and go, will recall that the feedback/signals felt through the rudder pedals can be very confusing and leads the pilot to make exaggerated inputs. Could this be why the FDR recordings show a series of mixed rudder inputs throughout the recorded data...dare I say questions that again should have been addressed!!??http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/confused.gif

Flautist as you seem to be 'in the know' with regard to Airnorth, do you know if the Airnorth Brasilias were all fitted with Electonic Trend monitor systems? If so it would be interesting to find out if the YD activation was a recorded parameter! Maybe the ECTM (if it had one) was totally destroyed or maybe not??

The question of why a Checkie would seemingly change his operational checking methods and standards so drastically over a relatively short time frame is very strange.

Prior to this accident Airnorth had reportedly operated the Braz with an exemplary record for a number of years, with a highly regarded T&C department setting a high standard for all its line pilots.

Which makes the actions/inactions of both of these well experienced drivers all the more bizarre, may they RIP!!

[FGD135]

Tend to agree that the standard of reports coming out of the ASTB is getting worse.

The ATSB report on the QF72 (Airbus 330 ADIRU spikes near Learmonth) was a disgrace.

The PPRUNE thread devoted to that report is here:

http://www.pprune.org/dg-p-reporting-points/472039-airbus-a330-303-vh-qpa-7-october-2008-atsb-report.html

[nomorecatering]

Is there a really good reference suce on Vmca and bank angle? Ive recently had a look through various instructors notes on Vmca and none mention about increasing Vmce with bank away from the failed engine.

[john_tullamarine]

none mention about increasing Vmce with bank away from the failed engine.

Plenty of reputable references around.

You might try the FAA Handbook (http://www.faa.gov/library/manuals/aircraft/airplane_handbook/media/faa-h-8083-3a-5of7.pdf) for starters at page 12-29.

If one graphs the Vmc variation with bank angle it is shallow near wings level and then increases rapidly with increasing favourable bank (Vmc decreasing) and, likewise, with increasing unfavourable bank (Vmc increasing).

A simple consideration of why bank affects Vmc will demonstrate the general effect of Vmc with bank .. either way.

[Dog One]

Does any one know if a inquest was held after the ATSB report was released?