Flap retraction

[tommoutrie]

Ok.. I'm bored of the ryanair private jet thread so can anyone put me straight on this..

On a normal all engines operating take off in a business jet we get airborne, romp through V2, go through the speed that the manual says the flaps can go up (V2+20 in mine) and then the most common trigger in companies I have worked for use a height trigger (400 feet for some, 1500 in the one I've just left) to retract the flaps. The challenger is regularly doing 200 ish by that point which is V2+70. I have tried to have the argument many many times that the wing doesnt care how high up it is and we should simply manage the drag the way the manufacturer intended but nobody is having any of it.

What do other people do?

[Cough]

Think the point is nothing to do with the wing. Its about the chance of moving the wrong switch close to the ground and giving yourself a bit of height to get out of trouble if needed.

[tommoutrie]

really? Whats your go-around height on an ILS then?

[PURPLE PITOT]

Company SOP 1000ft (agl), both donks or OEI.

I agree with you though, oei or on a noise departure, you manage the speed, but on a normal day, best to manage the drag.

[sevenstrokeroll]

if you are going so fast close to the ground, why not pull the nose up a bit and gain more altitude?

you may be super light on a reposition flight...do you have option of reduce thrust takeoff?

except for two special airports, we start clean up at 1000' agl, and reduce power at 3000'agl/afe

[PURPLE PITOT]

Deck angle vs gin and tonic in the back!

Derate not allowed by company. Glex climbs like a homesick angel even at max tow.

[tommoutrie]

Why do companies have all engine operating heights for retracting the flaps. In the case of your global for instance, what has height got to do with anything? I realise its an SOP (it is for most companies) but where does it come from? Its got nothing to do with the manufacturers. For the challenger the flaps can be retracted at V2+20. So why does anyone wait for a height?

[A Pandy]

At my company we call flap speed at V2+25 but do not make any turns until 400' agl.

[Pace]

TomM

It is a double edged sword! Extension of flaps on landing ie in the descent has the effect amongst other things of increasing drag and lift but the aircraft is descending so tapping into potential energy as another source of energy supplied by the engines.
The drag helps control the speed the lift allows the aircraft to fly at VREF for landing.
Takeoff is different we have the lift required to takeoff at a relatively slow speed but with that comes the drag.
Not just from the takeoff flap setting but from the gear and increased AOA!
The gear we get away quickly but we are at max N1 and at slow speed with no potential to tap into potential energy from the airframe should for any reason we need it and limited ability to reduce AOA.
Obviously the main concern in cleaning up in event of an engine failure or loss of power but there is another!
In still air all well and good but in shear conditions that slow speed can become critical.
Hence it is better to concentrate on flying the aircraft in a stable condition until well clear of the ground where you have the ability to tap into potential energy should you need to as well as reducing drag by reducing AOA before going from flap takeoff to zero.

Some say 400agl some 1000agl

Pace

[what next]

Hello!

In my part of the world, most major airports have noise abatement rules that call for a V2+10kt climb until passing 1500ft AGL before retracting flaps and accellerating. Therefore, many operators have made this (totally arbitrary!) 1500-figure part of their SOPs. Luckily, we are still permitted to do what we want if we precede it with "non standard" ;)

max

[Cough]

really? Whats your go-around height on an ILS then?

About the same as yours, for Cat I...

What I'm trying to suggest is you separate the act of getting airborne with the act of retracting the flaps. Think of it this way, by the sounds of the performance of your jet, you could probably get airborne and by the time you are airborne and have selected gear up, you could probably select flap 0 too.

So, you spend a good few years safely doing this. But you are now at the end of a veeerrrrryyy long week, end of an even longer day and an engine has just failed on you. Unfortunately your motor skills training says that when you select gear up, the flaps go too....

Its about, as I suggested above, error management.

And I'm not suggesting that it would be YOU making these mistakes, just that its possible...

[JonDyer]

And I'm not suggesting that it would be YOU making these mistakes, just that its possible...

You obviously do not know him then.

[Doug Neidermeyer]

Moutrie,
Its all to do with the profile, you raise the flaps at a height to take into account obstacles, NADP 1 NADP 2. If you are flying too fast for the flap speed then manage your speed...
If you retract too soon and then have an engine failure you might not clear the obstacle or on a two engine take off earn yourself a fine for noise...
The wonderful Capt Dyer knows that. He is a sky God...

[tommoutrie]

now you see thats all very interesting info.
APANDY, I think your lot have got it spot on. Get rid of the drag as early as possible - ie, flap up as soon as you're V2+whatever the minimim is, and the no turns before 400' is straight out of document 8168 so that makes sense too.

But why anyone would link a flap retraction to a height is beyond me. I've heard countless arguments and I don't understand any of them! There are no circumstances that I'm aware of where the height makes any difference. A change in flap selection can only be made because of speed - it says so in every aircraft manual written, and it never even mentions height!

Where I think the confusion lies is that there are various certification platforms for an acceleration altitude (ICAO, for instance, use between 400' and 1500') for the acceleration platform in the event of an engine failure but this still is not the criteria for flap retraction - its only about speed!

The arguments about reaching for a lever in the dark on a windy night when you are a bit knackered and finding the wrong one are a bit bizarre to me. Its certainly not a reason to be climbing against the significantly increased drag of having the flaps down! Noise abatement is an interesting one - very few business jet operators I know fly proper noise abatement departures because of the problem of limiting body angle (actually I don't think this is the real reason they don't do it - I think the real reason is they can't be bothered to train properly for it and believe their aircraft are quiet enough thanks very much and they are probably right). But even that doesn't justify leaving the flaps down and increasing the speed against that drag.

What I'm really interested in is where on earth the idea came from that flap retraction is linked to height. In lots of companies its the first call that isnt speed related and I have seen loads of COR's and MOR's related to forgetting to retract the flaps because the 400' call was missed. Big problem here, height is the wrong call to trigger retracting flaps - should be the V2+ call, and its PM moving the eyes to a different instrument at a critical moment that may be at the heart of this. What also bothers me is that some people think that an engine failure means you do something different with the flaps than what you do if the aircraft is operating with all engines (which is at the heart of companies choosing an arbitrary height for both). You DO do the same thing in the event of an engine failure - retract the flaps on the correct speed schedule...

what do you think..?

[tommoutrie]

.. thought of something else pace..

regardless of the conditions, in the event of an engine failure you would fly your plane at V2 flapped to acceleration altitude, take the flaps up at the appropriate speed, and climb away at V2+minimum, then go to an enroute climb speed at an appropriate time. wouldn't you?

So why is there a fear among pilots that selecting flap up at V2+20 will somehow make your aircraft unstable or prone to turbulance? Because its a very common misconception. The amount of lift you need from the wing is significantly reduced in the climb and you will be somewhere around 1.5 Vs so where does the feeling that the aeroplane needs 40 or 50 knots of extra speed from. All we are doing is degrading the 2nd segment climb and therefore wasting fuel and making noise.

just a thought..

[what next]

What I'm really interested in is where on earth the idea came from that flap retraction is linked to height.Historically this comes from airport design criteria which were matched to aircraft design. Around a round table (many round tables over the years) starting in the 1930ies, representaives of towns and aerodromes and representatives of aircraft manufacturers debated over the obstacle-free zones around aerodromes and the climb performance of aircraft. The aerodrome managers wanted to build as close to town centres as possible, the aircraft manufacturers wanted to use the cheapest engines on the market, and eventually that 400ft compromise evolved that found it's way into both aerodrome layout and part-25-design criteria. If someone wants to do a historical search, I'm pretty sure that 400ft-obstacle which was the origin of all this can still be identified somewhere. Some building around Idlewild or Tempelhof, who knows...

But where on earth this 1500ft-figure came from is a miracle to me. Totally arbitrary, nonsensical, yet part of many training programs and SOPs. Personally, I tend to disregeard it with the exception of my yearly checkride at FSI.

[Sillypeoples]

You have to understand that while we scratch our heads at the rationale of some checklists and SOPS, the reality is that you had a bunch of pilots and lawyers in a room cooking this stuff up at certification time....

'Ok, imagine the lowest time, pal/buddy/robot, Chief pilot culled inexperienced moron flying this plane...next to him is a pilot with even less time, less balls..a marshmellow, hoping the pilot has it right, because he's not going to say anything...so when do we have this guy retract the flaps?'

'Well if we have him do it right way...some guy, some where is going to rotate right at stall, then retract the flaps...can't have that...if we make him wait until 1500 feet, chances are some moron will accelerate to 300 kts and rip them off....so tell you what...let's make it 400 feet.....high enough where idiot #1 won't do it to quick.....not so high that idiot #2 will accelerate past Vfe. All those in favor say aye. Now just to cover our butts, let's make the climb out speed less then Vfe, so figure the times to climb for that...ok...so what am I missing? Come on guys...try to imagine a complete retard flying the plane.....what have we missed...yeah yeah...that's right...get the AP on fast...no early turns....good good keep them coming...'

[tommoutrie]

whats next
yes the 400' is part of document 8168 - its in the procedure design criteria bit in section 2 but it still has nothing to do with flap retraction.

Sillypeoples
you're kind of proving my point.. its got nothing to do with height. So when you say newbie might do it at this point or that point the only bit that matters is selecting them at the right speed. In fact, this is exactly where all the confusion comes from!

starting to see a theme here..

So, is there any reason at all for having a height trigger? Has anyone ever seen such a trigger in an aircraft manual?

I'll tell you where I think it all comes from. Flight flipping safety! I'm gonna ask them see if they know..

[Kak Klaxon]

It's to do with the distance it takes to get from V2 to flap retract speed when an engine fails, each take off or intersection has in theory a different altitude to raise the flaps governed by what you may fly into on the take off flight path.

400 feet is the minimum by regulation, do you really want to fly level at 400 feet trying to speed up to flap retract when it's 40 degrees at Al Bateen and you are heading towards downtown Abu Dhabi at MTOM.

In the mountains you may need to fly V2 to your engines 5 or 10 minute limit before being able to fly level for flap retract. If you don't buy take off perf or calculate it like we are supposed to then 1500 feet has got to be safer than 400 feet for level acceleration?.

[tommoutrie]

hello mr k

I can do a first principles net take off flight path calculation, thats not the issue here. My problem is that all engines operating, most biz jet pilots go rattling through the speed that they can retract the flaps and continue on up to whatever speed they get to by the time they get to 1000' or 1500' or whatever their particular company chooses to to use as a totally arbitrary flap retraction height.

Flap retraction heights don't exist - they are a figment of crappy understanding. There are level acceleration platforms which you can use to get from V2 to whatever speed you need to raise the flaps to the next position but all engines running you don't need them. So you can raise the flaps whenever you like as long as you have achieved the necessary speed.

Its incredible to me that very very few of us do whats in the aircraft manual. A mixture of tribal knowlege and lack of understanding has taught an enormous number of people to do something that doesnt make sense and can't be justified.

[Kak Klaxon]

The Bank Job is on TV, I can't comment further.

[B200Drvr]

I fly a G550, and 400 ft flap retraction certainly is in the book, thats not all it says, but on the 2 donks profile 400ft is flap retraction height.
What amazes me more, is that companies override what the manufactures set out as a profile.

[tommoutrie]

Any chance you could send me a page reference?
All I can find in the 550 manual is 06-02-00, normal take off with AT which call for gear then flap before the 400 foot call. I think whats in the 550 manual is correct but not what everyone actually does - never flown a 550 though.

Will try to post the page on here.

[tommoutrie]

https://skydrive.live.com/redir?resid=564144EC8608DFAE!10425

[tommoutrie]

https://skydrive.live.com/redir?resid=564144EC8608DFAE!10426&authkey=!ACCq-1twS2HQk7Q

[FrankR]

In the FSI document "G550 PTH", on Preface, page MTP-1, Gulfstream has stated that FSI is in fact their training partner, and that documents produced by FSI, are adopted as standard procedure for ALL Gulfstream aircraft.

On Page 19-13 (Rev 5.2, Oct 2011) it states that at 400 Ft AAL, the command "Flaps Up", Flight Level change" shall be given.

If you can get a hold of this document, it provides excellent standards training for pilots new to Gulfstream aircraft, and anyone flying an older generation aircraft where training documents may be lacking.

I'm not here to start a fight gents, just sharing what I got!

Hope this helps

FR

[tommoutrie]

thanks frank - that confirms my earlier suspicion which is that this comes from Flight Safety. Its definitely not whats in the G550 manual from Gulfstream because I've looked at that and tried to post the page. Its not in the Global manual, the Challenger manual, the Embraer Lineage manual, the Cessna Citationjet manual, or the Embraer Phenom manual.

I'm not trying to start a fight either, I'm simply trying to work out why we don't fly these planes the way the manufacturer suggested during a particularly critical phase of flight and why the belief that we should do otherwise is so deeply ingrained. FSI are responsible for teaching a very large number of pilots and there is a commonly held belief that if it comes from them then its gospel. Maybe it isnt..

[Kak Klaxon]

You need to hit the aircraft perf charts, for the CL 30 the acceleration altitude is called the transition segment, section 7-19 of the perf data in the operational reference manual.
I use APG for take off calculations and I was given the option when I opened the account to use 400 or 1500 for this segment. If the airport needs higher than 1500 it is published on the APG data sheet.
What normally happens if I can't do 1500 feet then an emergency turn is published by APG.
I fully agree that the aircraft I fly all wizz through flap retract and careful energy managment is required.
The argument for me waiting for 1500 all engines is that should an engine fail I don't need to remember what the profile should be as I do it all the time.
Never say never though as with a low initial level off after take off or with gusty conditions I use 400 feet and if I am freelancing I do what I am told.

[JonDyer]

The argument for me waiting for 1500 all engines is that should an engine fail I don't need to remember what the profile should be as I do it all the time.

And therein lies the answer in my opinion. It's got nothing to do with the aircraft and everything to do with the pilot. I have always believed that we should do exactly the same on every take-off - OEI or normal. When the engine starts spewing metal and the airframe is vibrating your fillings out of your head, you and your crew can just do as you have always done.

As for blasting through minimum flap retract or noise abatement - here's an idea - follow procedures - take off in FLC and reduce power after take off. That's what's in every ops manual for every company that I have flown the CJ for and I can count on one hand the number of pilots I know that do it.

[tommoutrie]

actually, therein lies the problem. You only need to remember a profile to fly at all because of the warped logic coming out of flight safety. The only thing you need to remember (as far as the manufacturers are concerned) is that the flaps on the CJ can come up at V2+10. On the Challenger its V2+20. Phenom its V2+1 and so on. And you always do that whether an engine fails or not. Should you lose an engine before V2+10 (for the CJ and whatever for other aircraft) you will lose a large percentage of your available thrust. You may, therefore, need a level acceleration platform to achieve V2+10 in order to raise the flaps and climb away clean. ICAO introduced two certification platforms - 400 feet and 1500 feet. You will probably remember that the straight CJ happened to be certified at 400 feet but most aircraft now are certified at 1500 feet for a level acceleration platform. The reason was to do with time available at max thrust OEI. In fact, the perversion of leaving the flaps down and climbing at higher speeds against the induced drag causes quite a serious problem - should an engine fail at higher speed when you are still in the take off flap condition, whats your plan? Just consider for a moment where you are - climbing at 160kts against the flap, engine fails at 900 feet (very common for a birdstrike) what do you do?

The reason for taking the flap up at the speed the manufacturer suggests is that is where the L/D curves are closest for the different wing configurations. What you get, therefore, is minimal pitch change, and the most efficient combination of lift and drag for the changing speeds. As soon as you are appreciably over this speed you are simply creating more drag than you need to for the lift you need and there is no case at all for doing this on take off. Its arguable that this is desirable on approach so that you have an element of drag control to help lose speed but on take off all you do is degrade the climb profile and therefore have an associated decrease in safety and increase in noise. Where does it come from?

I think there is quite a serious climb performance gradient issue here which I've done some maths on and there is also an awful lot of confusion caused by poor understanding and incorrect teaching by some of the training organisations (not just flight safety). Pilots talk about different profiles for an all engine operating take off and a loss of thrust condition but in reality they are exactly the same. I just really want to check that I'm not missing something and make sure that no manufacturer issues a manual that tells us to do what everyone is actually doing.

[tommoutrie]

Hi Klaxon, checked and thats all OEI data. Not all engines operating. All that does is add to the fact that you shouldnt be climbing with take off flap at anything significantly above the flap retraction speed otherwise you dont really know where you are along the all engines operating take off path..

[Kak Klaxon]

Sorry I am getting lost now, I only calculate a single engine NTOFP, maybe you should post in the tec section where all the boffs hang out. Good luck:)

[tommoutrie]

you calculate a single engine net take off path (or more likely a bit of software does it for you) then fly an all engine operating take off and you don't do it the way the manufacturer intended. You hold a take off flap setting, climb against drag, make more noise than necessary, end up in an unknown and unprovable vertical situation with regard to SID gradient, and you use more fuel. And there's no reason for it.

I'll put 100 quid on it. Does that help?

[tommoutrie]

and its not a boffs question. We all do it wrong, we are pilots, we are taught to do it wrong. And I'm pretty sure I can prove it.

Come on, I'll up the bet if you like. But its two way...

[apruneuk]

On the Hawker, we regularly do flap 0 take-offs. The second segment climb performance is calculated using our computerised programme and/or the aircraft manual and is often better than using flap 15 ( not to mention one less action to undertake at a particularly busy stage of the flight).

Some flight departments like to standardise procedures for all types and this could range from a Citation up to an Airbus. Clearly there are different requirements for different aircraft and a one size fits all policy sometimes appears a little non-sensical. Airmanship dictates how we operate and any variations from SOPs are discussed beforehand and need to justifiable to the men in suits at any subsequent board of inquiry.

AP

[tommoutrie]

AP you are working for the enlightened and thanks for your post. The 125 series aircraft is descended from the Dominie I think which was originally used as an instrument training aircraft by the RAF. When it was used by them it almost always did a flap zero take off because, as you say, its already clean that way and the 2nd segment climb is better. Bizarre then that when its used as a business jet the SOP's get fannied around with and it becomes the norm to take off with flaps set at 15(I think). And then, because the dolt that has written the part B has copied it from someone else, this confusing rubbish about 1500 feet gets thrown into the equation. I advocated taking off in the CJ flap zero at my previous employer and got all sorts of snipes for being experimental.

Nobody want to take the 100 quid bet? I'll up it then to 200. Flight Safety instructors particularly welcome..

[apruneuk]

Tommoutrie
Yes, the modern Hawker 125 series is descended from the Dominie albeit with more powerful fan engines as opposed to the original constant thrust, variable noise Viper turbojets.

There seems to be confusion between second segment and noise abatement climb profiles and what they are trying to achieve. 1500' agl is the end of the second segment climb and is the point at which you will accelerate, retract flap if used, and accelerate to en-route climb speed, having had an engine fail at V1. The calculation allows for the aircraft in this condition, if flown straight ahead at V2 to 1500', to clear all obstacles to that point. If this is not possible then an emergency turn procedure is devised. At least, that is how our performance programme works, and it will give profiles for both flap 15 and flap 0.

Noise abatement profiles assume both engines operating and are designed to leave as much noise in the vicinity of the airport as possible with as much height gained over distance travelled as possible (vx) prior to cleaning up and reducing power to a level sufficient to give an acceptable rate of climb or height in time (vy) with minimum noise nuisance.The goal of a noise abatement climb is to reduce noise whereas the goal of second segment climb is to clear obstacles.

Now consider a standard departure where both engines function correctly. If the performance calculation shows that you could clear all obstacles to1500'agl if the aircraft is flown correctly with an engine out at V1 with flap 0 or flap 15, then all that is required to stay safe with two engines operating is a sufficient rate of climb to satisfy the requirements of the SID. This is generally less than a 5% gradient which is the same as a standard ILS, or 750'pm at 150kts. The best two engine performance for our aircraft is achieved by initially pitching to 12degrees and retracting flap and reducing power at the calculated flap retract speed, which is usually reached by 400'agl. Leaving flap extended beyond that speed will result in unnecessary drag and a performance penalty. I generally accelerate after flap retraction to 180-200kts for the initial turn on the SID and control rate of climb with power to avoid exceeding 1000'pm in the final 1000' to level-off (our SOP). This profile exceeds the obstacle clearance requirements of a standard SID four-fold on an ISA day at sea level with climb power set!

Clearly, all departures are briefed and profiles adjusted to suit conditions, terrain and airport requirements. I can't think of any scenario, however, when it is advantageous to leave flap at take-off setting past calculated flap retract speed on our aircraft with both engines operating.

Sorry for the ramble, I really haven't been drinking!

AP

[tommoutrie]

That sounds absolutely spot on. I think you are in a tiny minority of operators who are doing it right. Genius! Hey at least that confirms I'm not completely nuts!

[mutt]

The CAE Manual for the G4 states "At VFS (Minimum), select FLCH" so this would have you retract the flaps based on a speed rather than a height.

But of course that's not the way we do it :)

The 400 feet froms from aircraft certification where the limits are between 400-1200 feet, the 1500/3000 feet comes from ICAO noise abatement. They were not developed to meet the same goals, in the same sense as the certified gradient will not protect you for the SID departure gradient requirements.

Mutt

[tommoutrie]

aarrgh!! More evidence from the manufacturer! Why don't we do it like they want us to?

The ICAO level acceleration platforms are 400 to 1500 feet - they are in document 8168. In fact you can choose to certify your plane using any level acceleration platform between and including those two heights but all of that is to do with OEI operation.

NAP1 and NAP2 are noise abatement procedures for close in and slightly further away noise reduction. These are applicable to all engine operating conditions and almost all biz jet operators ignore them deciding that the body angles achieved are too great (there's a body angle max suggestion of 20 degrees). What most operator choose to do is leave the flaps down and accelerate anyway which degrades the take off path and actually causes more noise.

All of this is supporting my argument.

Tell you what... I'm upping the bet to a grand...

[tommoutrie]

come on.. somebody clever must be able to prove that the way virtually every business jet departs is the way the people who build them intended. Somebody must be able to show that I'm talking rubbish. I mean, come on, we all must be doing it the right way...surely..

a thousand pounds

its my real name

I can't run away

make me look foolish and get some cash

[mutt]

You must remember that you are operating a relatively powerful corporate aircraft, when the regulations were written this wasn't the case, you are also assuming that the aircraft has a better climb gradient with a lower Flap setting, once again this isn't always the case.

Under FAR25, the aircraft has to be certified to meet all the required gradients with an engine out, this information is only applicable to us when we need to clear takeoff obstacles. How do you protect yourself for clearing the obstacles if an engine fails right after you have retracted the flaps?

Mutt

[Empty Cruise]

Most places, 95% perhaps, what OEI AA you chose has no consequence whatsoever. The remaining 5% it has a very clear and immediate impact, and buggering around with it can terminate you if you lose one donkey.

For that reason, I am sure we all agree that the OEI AA needs to be respected, full stop.

Now, let's say you have all donkeys burning - so you can retract your flaps at a lower altitude, right?

Consider losing your engine before you reach en-route climb speed, ie between V2+10-20 and Venr. You now have to continue acceleration or stay at whatever speed you're at, in neither case knowing where you are in respect to obstacle clearance. Or could re-deploy flaps and drop back to V2+10, but that somehow defies the purpose of the exercise...

You know that you're quite a bit above the OEI flightpath when you start retracting at eg 400 ft, but how much? Enough?? If you have a 1500 ft ADER acceleration height, you might make it up there and still be above the OEI path from 35ft at this stage - but what if it's 2000 ft? 3000?

Problem is that if you roll the flaps before you reach your obstacle clearance altitude and you lose a donkey immediately after, you have no scooby doo about where you are or will end up in relation to your OEI path.

OEMs only build the things and specify the minimum certified height they want you to retract the flaps. Consider CMF, ASE, INN, SFJ etc etc etc. - your AA is waaay above cert minimum in all these cases, so by respecting your performance needs, are you flying the aircraft contrary to how the OEM tells you how to fly it?? A careful look at the AFM will reveal correction tables for 2nd segment extended above 400/1500 ft respectively.

In other words - the OEM only builds and certifies your aircraft - you, your company and your authority must then come up with how you operate it. Suffices to say that if you roll flaps at 400 ft at either of the above mentioned places or their relatives, you clearly have had an imagination failure :} You don't need to put yourself in that (flapless) position, so why do it?

Deck angle limits need to be respected, but the old idea about the owner firing your sorry ass because you exceed 8-10 degrees? Had a very nervous owners wife out of INN on a CL30 telling me not fly out of there too steeply :D flew the usual profile reaching 18 deg ANU, she afterwards said it was the best takeoff ever... They don't often notice a deck angle - but they DO notice a shoddy (ie too fast) rotation rate...

Anyone here ever actually had a pax complain about deck angle?? Would be interested to run a poll...

[mutt]

And Empty Cruise wins the 1000 quid :):)

Mutt

[tommoutrie]

Nope, still my money I'm afraid chaps.. For the sake of not typing too much lets stick with an aeroplane where the flaps can retract at V2+10.
2nd segment climb gradient is ALWAYS better at V2+10 clean than it is a V2 flapped which are the two conditions you have the climb gradients for. Therefore, when you are all engines operating and accelerating through V2+10 you MUST retract the flaps to ensure that in the event of the engine failing you remain above the required gradient. If you do what most operators do and remain with the take off flap set but accelerate above V2+10 and then the engine fails you have a draggy aircraft trying to climb with one engine out. If you had already got rid of the flap the aircraft would already be climbing as efficiently as possible.

Its a two way bet... im a grand up now..

[tommoutrie]

pick an aircraft, any aircraft, lets get the charts and I'll prove it to you

we've all been doing this wrong for so long that nobody wants to believe it!

tomorrow I'm going to prove the world is, in fact, flat

[tommoutrie]

and no, never had anyone mention deck angle. I took a photo out of the window of a 320 out of Heathrow recently sitting in the back on the way to paris and I've tried to measure it against the horizon and the deck angle is pretty close to 30 degrees. Another GA myth!

[Empty Cruise]

Tom,

Just a quick q - on your chosen aircraft where you may retract the flaps at V2+10 - what is your en-route (ie clean) climb speed? What is your manouvering speed clean?

I am not saying that no aircraft exist where you don't climb clean at V2+10, but for most of the serious kit out there, V2+10 (or whatever is specified) is a transient speed, not a speed you continue flying.

On my current aircraft the gap between flap retraction (V2+12) to Vfto is in the order of 20 kts, and on the 737 it was around 25 kts.

If you can explain how you get from V2+10 to Venr without busting your gradient OEI (or indeed, explain how climbing below your Venr clean improves the gradient OEI), I shall be most impressed - or a grand richer :ok:

[tommoutrie]

no problem. For the case where the aircraft is one that cleans up at V2+10 lets go for the CJ. The process in the CJ is if you take off with flap 15 and happen to have an engine failure you continue at V2 up to whatever platform height you are able (engines are limited to 10 mins for the later ones and 5 mins for the early ones at max thrust). If you make 1500 feet you fly level, accelerate to V2+10, clean up and climb away at that speed to your 10 minute engine limit where you reduce thrust to max continous, accelerate to Venr, and then continue the climb as necessary. In reality, most people just accelerate at the 1500 foot platform to Venr and climb away clean from there. If you look at the charts for a flap 15 take off and a flapless take off the 2nd segment climb gear up OEI is always better for the clean condition and it just so happens that the speed for the flapless condition is almost exactly the V2 +10 of the flapped take off. Which is why you are supposed to retract the flap passing V2+10 when you have all engines operating.

I'm currently on the Challenger and its exactly the same for that except that I don't have clean take off tables for it because you can't do it. However, if you plot the L/D of any commercial wing you will find the reason the flap up speed is what it is is that is where the L/D curves are closest. Venr is the enroute climb speed single engine and you use that once you've run out of max thrust time and have to go to max continuous.

Which aircraft are you on? I'll get the manuals and have a look at the actual pages for your type to make sure I'm not talking balls and if I am I will post over the cash

[tommoutrie]

does my challenger count as serious? cos its the same on that..

[Empty Cruise]

yep, Tom - the 300 is a decent piece of kit - same there, though, V2+10 (or whatever it was, haven't flown it for 3 years now) is below Venr - which raises the question why Bom in their wisdom have not chosen Venr=V2+10? :p

[tommoutrie]

The speed for flaps up (V2+20 on my 601) will still give you best angle. A better angle than V2 with flaps 20. The enroute climb speed, commonly called Venr, gives you best rate. Which is what you want once above your platform except in very unusual circumstances. Its also slightly easier to fly because you are going faster and the fin works better so you need less rudder and consequently there's less drag.

[tommoutrie]

Point is, most folk ignore all this and the initial climb out is at increasing speed - which is fine if you take the flap up but its definitely not if you leave the take off flap set. Its grossly incorrect to be doing 190 with flap 20 still selected in the challenger yet thats what my last companies SOP's called for. My old company are happy climbing the challenger with flaps 20 at V2+70 on the way up to 1500 feet. And its utter, utter rubbish! The flaps should go up at (maybe shortly after) V2+20 on a challenger on any take off. The theory is true for any pretty much any aircraft.

[tommoutrie]

Just been looking at the 737 and 777. All engines you climb at V2+15 to 25 and take the flaps on schedule which appears to be roughly V2+30. So again, you don't go through the flaps up speed without taking the flap up!

its all the same..

we've all been doing it wrong and contrary to popular belief it actually does matter!

[A Pandy]

For the sake of adding to the discussion, as I mentioned in a previous post when operating our Lear 45s we call for flaps at V2+25 as per the manual. However I have just finished a type course on the Gulfstream G650 and Flight Safety International teaches for flaps to be raised at 400agl. The Operating Manual as well as the Gulfstream checklist call for flaps to be raised at positive rate just after the gear. No mention of speed or altitude. Same call for flaps 10 and flaps 20 take-off.

[gaunty]

Gents enjoying the chat and great to see a good work out on why?.

The below may contribute to the debate as to where the 400-1500ft numbers derive.:cool:
I always go back to 1st principles when I can, and D.P Davies "Handling the Big Jets" is a great primer. The title is a bit confusing insofar as that it contains a very detailed discussion of the design tricks and trade offs the manufacturers make to get to their target specification.

FAR Part 25 has some very instructive reading for aircraft >5700kgs.

FAR. Part 25 as amended, was previously 25.77
§ 25.111 Takeoff path.

(a) The takeoff path extends from a standing start to a point in the takeoff at which the airplane is 1,500 feet above the takeoff surface, or at which the transition from the takeoff to the en route configuration is completed and VFTO is reached, whichever point is higher. In addition—
(1) The takeoff path must be based on the procedures prescribed in § 25.101(f);
(2) The airplane must be accelerated on the ground to V EF, at which point the critical engine must be made inoperative and remain inoperative for the rest of the takeoff; and
(3) After reaching V EF, the airplane must be accelerated to V 2 .
(b) During the acceleration to speed V 2 , the nose gear may be raised off the ground at a speed not less than V R. However, landing gear retraction may not be begun until the airplane is airborne.
(c) During the takeoff path determination in accordance with paragraphs (a) and (b) of this section—
(1) The slope of the airborne part of the takeoff path must be positive at each point;
(2) The airplane must reach V 2 before it is 35 feet above the takeoff surface and must continue at a speed as close as practical to, but not less than V 2 , until it is 400 feet above the takeoff surface;
(3) At each point along the takeoff path, starting at the point at which the airplane reaches 400 feet above the takeoff surface, the available gradient of climb may not be less than—
(i) 1.2 percent for two-engine airplanes;
(ii) 1.5 percent for three-engine airplanes; and
(iii) 1.7 percent for four-engine airplanes.
(4) The airplane configuration may not be changed, except for gear retraction and automatic propeller feathering, and no change in power or thrust that requires action by the pilot may be made until the airplane is 400 feet above the takeoff surface; and
(5) If § 25.105(a)(2) requires the takeoff path to be determined for flight in icing conditions, the airborne part of the takeoff must be based on the airplane drag:
(i) With the takeoff ice accretion defined in appendix C, from a height of 35 feet above the takeoff surface up to the point where the airplane is 400 feet above the takeoff surface; and
(ii) With the final takeoff ice accretion defined in appendix C, from the point where the airplane is 400 feet above the takeoff surface to the end of the takeoff path.
(d) The takeoff path must be determined by a continuous demonstrated takeoff or by synthesis from segments. If the takeoff path is determined by the segmental method—
(1) The segments must be clearly defined and must be related to the distinct changes in the configuration, power or thrust, and speed;
(2) The weight of the airplane, the configuration, and the power or thrust must be constant throughout each segment and must correspond to the most critical condition prevailing in the segment;
(3) The flight path must be based on the airplane's performance without ground effect; and
(4) The takeoff path data must be checked by continuous demonstrated takeoffs up to the point at which the airplane is out of ground effect and its speed is stabilized, to ensure that the path is conservative relative to the continous path.
The airplane is considered to be out of the ground effect when it reaches a height equal to its wing span.
(e) For airplanes equipped with standby power rocket engines, the takeoff path may be determined in accordance with section II of appendix E.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-6, 30 FR 8468, July 2, 1965; Amdt. 25-42, 43 FR 2321, Jan. 16, 1978; Amdt. 25-54, 45 FR 60172, Sept. 11, 1980; Amdt. 25-72, 55 FR 29774, July 20, 1990; Amdt. 25-94, 63 FR 8848, Feb. 23, 1998; Amdt. 25-108, 67 FR 70826, Nov. 26, 2002; Amdt. 25-115, 69 FR 40527, July 2, 2004; Amdt. 25-121, 72 FR 44666; Aug. 8, 2007]

Part 25.101 thru to the end describe all the certification design requirements.

BTW I think I saw some mention of the CJ, these aircraft whilst jet are <5,700kg and therefore actually Part 23. There are a number of excellent design and cost reasons why these manufactrurers use the less strict Part 23 rules although provide Part 25 type take off perfromance.

enjoy.:ok:

BTW for very sound legal reasons, FSI teach exactly, the manufacturers FAA certified AFM, IMHO any operator that goes away from that document better have a very very good reason if it goes pear shaped, the lawyers will make mincemeat out of you. Too many COMs and procedures are based on folklore or the CPs personal prejudice. The AFM is the law, period.

Qantas thought they knew better than Boeing and came within an millimeter of a hulls loss with many lives. Fortunately very the close shave brought them to ther senses.

[Empty Cruise]

Tom,

Must have misunderstood your first post - thought you advocated flying fixed pitch and retracting when you reach V2+10 or wassever...

Now see you say - either that way or fly a fixed speed (V2+10-30) to AA, then accelerate and take flaps on schedule.

The latter makes a lot of sense in my book, the former not ;-)

As for Venr being a rate rather than a gradient speed - where does it say so?? :)

[tommoutrie]

I dont know where it says it but I have L/D curves for it and although its slightly slow (but not very) its close to it.

Hello Gaunty - All the net take off flight path stuff refers to one engine inoperative operation and the thrust of my posting this in the first place is that I don't think training organisations like Flight Safety do, in fact, teach what is in the manufacturers books. I think they get so fixated on engine failures that they teach a normal take off incorrectly. I think operators don't really know or care what they put in their SOPS and because the CAA don't approve that bit (they only accept it) they don't care either.

However, I think it is actually important. Flown the way that everyone currently does it we make more noise and degrade the flight path and use more fuel. Not much more, granted, but some. And in a plane like a Challenger if you save a little bit near the ground and carry it to height it takes you a little bit further..

Also, nobody has actually said what their plan is should an engine fail when they are at 1000 feet, take off flap still set, V2 +50 ish. At V2+50, are you still on the required SID gradient? Who knows - your rate of climb is pretty good but your forward speed is much higher so you don't actually know. Then, if you don't have a plan as to what you are going to do, how can you be sure (or prove to the authorities in a theoretical way) that you will stay above the PDG?

My belief is that FSI and the ilk have simply missed whats going on here and confused the OEI situation and the all engines operating situation.

Am I convincing anyone or is this just rubbish?

[tommoutrie]

does anyone know anyone from FSI who could have a look at this?

[JonDyer]

Must have misunderstood your first post - thought you advocated flying fixed pitch and retracting when you reach V2+10 or wassever...

So did I and I've read back through it all twice now.

Also, nobody has actually said what their plan is should an engine fail when they are at 1000 feet, take off flap still set, V2 +50 ish. At V2+50, are you still on the required SID gradient?

Which required SID gradient? Are you talking noise abatement, obstacles in flight path / airspace, Step climbs or OEI gradient? Which?

Am I convincing anyone or is this just rubbish? Normally my default position with your ideas is no... but I must admit I am intrigued and I'm wondering if you are right.

What you are wrong about is Kak Klaxon's suggestion that you post a link to this thread in Tech Log. If you do that you may well get a definitive answer and you may win or lose your money.

[His dudeness]

Also, nobody has actually said what their plan is should an engine fail when they are at 1000 feet, take off flap still set, V2 +50 ish. At V2+50, are you still on the required SID gradient?

I for one would pull back to V2, thus bleeding speed for altitude and then continue on V2. What gradient one does at V2 + 50 with flaps T/O nobody really knows hence back to V2. On my airplane, pulling back 50 knots in 1000ft would give me more than 500ft anyhow, so I could accelerate again to Venr. (given that one would not need more 1500agl for the SID. Other wise V2 to safe ALT/FL)
We go to flaps 0 passing 400ft AND V2 + 20 minimum...

[tommoutrie]

Hello Dudeness
I think that given the situation lots of us put ourselves in thats a good plan but really the aircraft should already be clean because you've passed the flap up speed (not sure what you fly, soverign maybe). So with the take off flap still set and at a speed appreciably above the flap up speed you are generating extra drag and as soon as the engine fails this becomes a more serious problem. If the flap was already up you would be reducing the speed to the flap up speed or Venr as appropriate and making no further configuration change, you would not be coping with the extra drag, and at all times you would be climbing as well as the aircraft possibly can. With the take off flap still set above the flap up speed you aren't.

Jon, deep down, you've got a sneaky suspicion that I'm onto something and the reason is that you know how Part B's get copied (did I say copied, I meant written)! Worse still, the operator I have just left refuse to change the way they teach us to fly the take off but the wierd thing is that whats in the part B is actually far closer to correct than what we actually do. But nobody reads it and nobody takes any notice of it.

The problem is that nobody thinks it matters but climbing inefficiently, burning extra fuel, making extra noise, and having a rather wierd situation should you lose a powerplant at some point after the flap up speed are all very good reasons to think more carefully about this. There dont seem to be any good reasons at all to keep doing what we are doing!

Just to make the point, Dudeness, whats the reason for the 400 foot call and why do you use it as a flap up trigger? Where has it come from?

(honestly chaps, not being adversarial, just want to work this out)

[JonDyer]

Tom, you do recall that on the CJ (for example) there is no 400ft call, don't you?

The SOP is: Above 400ft AAL and V2+10kts PF calls for:
Flap Up
I realise the 400ft prohibition is still there, and I know many people call it, but there is no call in the SOPs.

I'm not splitting hairs - a call would be yet another layer upon your (alleged) layer of nonsense.

Why not ask eckhard (for it was he what wrote it) where he got the 400ft from? My guess is "The Citation 500 SOPs"

... and so it goes on!

[His dudeness]

We do have a checklist in our airplane... :eek:

It says:

AFTER TAKEOFF/CLIMB
1. LandingGear ......................UP
2. Flaps..................0° (V2 +10 knots and at or above 400 feet AGL)
3. Throttles.................. MCTDetent
4. YawDamper................ AsDesired
5. Autopilot (above 400feet AGL)......... AsDesired
6. Pressurization................... Check
7. SEAT BELTS and PAX SAFETY Buttons . . . As Required
8. Anti-Ice...................AsRequired
9. Altimeters/RECOG Button (at transitionaltitude) ........... Set/OFF
10. APU (prior to climb above FL300). . . . . . OFF (refer to Normal Procedures, “APU Shutdown”)

And it is a Sovereign, meaning this CL is basically from FSI....

We use + 20 instead of + 10, just because the Sov goes thru these numbers so bloody quick and one usually can´t hold V2+ 10 really...

I do know a guy that would raise flaps almost immediately after takeoff in his CJ3. I don´t like it too much to be honest. Maybe I´m just slow or stupid, but I like 'to settle in' before changing config. IF I understand 'it' correctly, I can meet all the requirements the way we do it, provided the V2 OEI numbers are achieved. And thats what I´m interested in most, to be honest...

[tommoutrie]

flight safety again. Can't say I'm shocked.
Dont forget, I'm not saying you necessarily need to hold V2+10 - thats a noise abatement issue and until we routinely de-rate its totally impractical. What I'm suggesting is that we should select flaps up as soon as we can. If you made the configuration change as soon as you're allowed to I suspect you'd hardly feel it whereas if you make it when you're considerably faster the pitch change is much greater which contributes to the feeling of sinking etc..

I'm going to see if I can find a Cessna manual for the soverign and see what it actually says rather than one thats caught a nasty FSI

[A Pandy]

The following comes straight out of the Gulfstream G650 Operating manual.
Normal 2 engine take-off, at positive rate gear up and flaps up. Select FLCH which will command auto throttles to go from V2 to 200kts. No mention of 400'. The 400' call is from the FSI training manual.
Engine failure above V1.
Climb at V2 to 1500' then accelerate to V2+20 flaps up. If engine failure occurs after passing V2 maintain V2+10 as this gives the maximum climb gradient.
In the sim we were using 400' to retract the flaps but this is a Flight Safety call and is nowhere to be found in the Gulfstream documents.

[tommoutrie]

a pattern doth emerge..

I think it may be worth asking Flight Safety.

I shall do it in the morning and report back.

all...very....interesting...

(quite jealous of your G650)

[Cough]

I took a photo out of the window of a 320 out of Heathrow recently sitting in the back on the way to paris and I've tried to measure it against the horizon and the deck angle is pretty close to 30 degrees

About 15deg NU for an average day. 30 degrees NU = full back stick and maintain....(Normal law) (speed will be going badly south...)

[mutt]

Normal 2 engine take-off, at positive rate gear up and flaps up. Select FLCH which will command auto throttles to go from V2 to 200kts I'm surprised that there is no "speed check" included before retracting the flaps!

Gulfstream say almost the same thing in the G4, at VFS (minimum) select FLCH.

So if you want to look at things in isolation, there is nothing stopping you are per the manufacturers procedures from retracting the flaps at V2+X and 100 feet. This is exactly the way that you wanted. However if we dont look at things in isolation and the nice "FED" shows up and asks you how you are going to comply with the regulation pertaining to clearing all obstacles in the takeoff flight path, the only way that you can prove it is to refer to the manufacturers AFM (or software), this is based on the certification requirements of FAR 25 with a define profile where 400 feet is stated, so you would have to be able to show that you were in compliance with those procedures.

If FSI teach you the procedures in isolation, then they have just shouldered the legal responsibility for you flying into a mountain.

Mutt

[Sillypeoples]

Obstacle Clearance

[G-450 AFM 5.6] The obstacle clearance procedure is to climb with landing gear retracted, flaps in takeoff position at a speed of V2 to at least 1500 feet above the takeoff surface. Use of the obstacle clearance data in this section will ensure that obstacles will be cleared by a minimum of 35 feet for dry runway takeoffs. For wet runway takeoffs, 20 feet must be added to heights read from the charts to assure 35 feet minimum clearance. Climb performance is referenced from 2 locations — 1) Reference Zero and 2) the Departure End of the Runway (DER). Reference Zero is the point along the runway where the aircraft attains a height of 35 feet for dry runway operations or 15 feet for wet runway operations. Per TERPS (Terminal Instrument Procedures) criteria, SID (Standard Instrument Departure) climb requirements are specified from the DER. Accordingly, when extra runway exists beyond Reference Zero to the DER, different available climb performance is computed for these different reference points. Shown below is a schematic which illustrates the resulting climb performance capabilities from either of these reference points.


Summary: V2+10/400 AND Obstacles cleared....is when you retract flaps..

Zero Zero out of Eagle..where you reduced fuel, changed departure time to the coldest time of day...ect...you are going to leave the flaps down and V2 all the way up.

Code7700 (http://code7700.com/performance.html)

[tommoutrie]

The net take off path you just described is OEI. What I'm trying to get across is that most operators, on a normal take off, leave the flap in the take off position, go blasting through V2+x, get to 1500 feet at V2+40 or 50 or in many cases more and retract the flap there. Hopefully this is clearly wrong. Many companies SOP's talk about a flap retraction at 1500 feet and those that don't will tend to use a flap retraction at 400 feet. Even the example you just showed me for the 450 doesnt mention 400 feet.

If you look at your marginal day out of Eagle (don't know Eagle, going to read Sion) the argument still holds. If you take off all with all engines operative and somehow manage to make it to your retract speed you WILL have a better gradient if you retract the flaps there EVEN if one engine then fails. This is for a normal take off remember - we're not talking about a noise abatement procedure which calls for a Vx climb to 1500 feet for noise.

The important thing is that the flaps should go up once you've passed the flap retract speed REGARDLESS of the height. I can't find any references in any flight manual anywhere that requires a conditional height for an all engines operating take off. If you are going to take off and remain below the flap up speed then thats great but why do Flight Safety take it upon themselves to teach everyone that there's a 400 foot condition for raising the flap when its clearly rubbish. The level platform (400 foot, 1500 foot, made up 1000 foot for lots of companies) is for acceleration and is called an acceleration altitude. If you don't need it its irrelevant.

Are there any votes for the motion at all? Or is it just me...

[Kak Klaxon]

Do I win a Thousand ? I can put it towards getting this Part FCL licence issued and next years ETS charge.

[gaunty]

tommoutrie

I will be totally amazed if FSI teach anything but the AFM, otherwise they are on very very thin legal ice.

If they express a view otherwise I would get it in writing, with an indemnification. Warren would not be pleased.

Our experience is that if asked about non AFM approved manouevres they may express a personal view but will always return to the manufacturers AFM.

If the manufacturer allows their approved training org to do otherwise they will be codefendants, I dont think so.

You get exited in my organisation for using otherwise, and if a regulator (believe me in my part of the world they sometimes try) or an auditor tries to impose a personal prejudice outside the AFM as a condition of an approval then it's game on.
It usually starts with a polite but firm request from me for a formal personal indemnity from them and their organisation and always ends in a white flag. I have found, at least in my country, the amount of misinformation, lack of background knowledge, prejudice, legend, folkore, and Chief Pilotology astounding. I am fortunate to have been able to hand pick and mentor some outstanding people.

As I am sure you are aware the AFM is the FAA approved reduction of the performance derived from the manufacturers certification process and yes is based on OEI.

SillyPeoples has got it in one, its really all about the departure runway obstacle clearance basket (we use APG to provide RTOW which simplifies the preflight planning matter somewhat) within which we operate and ALL the calculations are based thereon for all combinations of where you may find yourself OEI at any time up to the end of the takeoff phase. The default position for the OEI calculation is V1.

Simply put, if you fly the speeds/AFM to 1500ft, or higher if the particular departure requires, you are gauranteed to have the required obstacled clearance whether one or both are going. Thats what V1 is about.

So, mess with that and you are now a manufacturers test pilot, in an uncertified aircraft and or only guessing where you might lay in the basket up to that point. "Well M'lud up to that point everything was going so well I thought I'd just wing it from there."

The subject under discussion seems to suggest that at some arbitrary time during the take of phase the pilot decides that everything is going just swimmingly so lets clean up and get going.

Sure the modern aircraft can perform all manner of interesting things but not what it can't.

What you can be sure of is that the manufacturer has squeezed the living daylights out of the performance calculations in your manual up to the certification limits available.
Why would they not do otherwise, they are trying to sell you an aircraft with the best possible performance, the FAA on the other hand are intent on keeping them honest.

I might be wrong but if they thought there was a better way it would be in the AFM.

Your theories may well be correct, but this little black duck wont be chancing his arm outside the AFM.

I have sat in court as an expert witness too many times and seen too many unintentional test pilots try to defend what they thought was a good idea at the time.

Anyway I have been wrong before.

[gaunty]

Tom

Just noticed in your post.

" If you don't need it it's irrelevant". Too true, but one have to have your eye on the FED. :=:E

FSI may be pedantic but the "400ft" clearance remains as a benchmark, is it not he pilots responsibility to satisfy that condition.

Further consider FSI teach on the assumption that this is your Initial, recurrent is a refresher on that so back to "kindly"'perhaps.

How do you teach or recognize different levels of experience/dumbosity. Some of their pupils are smart some are dumb, so they have to default to dumb.

A corporate dept near me had their so called legend in his own lunchbox sent home, despite their considerable teaching skills, as he was unable to handle the upgrade. Not surprised mind you, but humbling for him nonetheless, to his credit he eventually got there but not without an enforceable undertaking to have an approved pilot in the cockpit for a period.

Interesting stuff as the performance of the aircraft we now have improves beyond belief.

I never thought I would ever see M.83 in the climb schedule. Clearly the installed thrust required to get over M.9 in the cruise is way more than necessary to get away from mother earth in a sprightly manner. I hasten to add I am not rated in the type but have spent a bit of time in the sim and aircraft.

[B200Drvr]

Tom
Just a thought, is the 400 ft not just giving time for the gear to be completely up before you start the flap up selection!! On the 550 the flaps take a very long time from 10 -0 my guess is you are easily through 1500 feet on a normal SID before the flaps are fully retracted. So if you started retracting them at 1500 ft on a normal climb, you will probably be at 250 kts before they are retracted fully depending on the MSSA that you have set in the box to maintain 200kts.
You really don't have time to do it before 400 ft because of speed and then selecting the gear up.

[B200Drvr]

PS, So far this is one of the best ever threads on PPRUNE, I hope it stays that way, it is informative and thought provoking!!

[His dudeness]

I will be totally amazed if FSI teach anything but the AFM, otherwise they are on very very thin legal ice.

They won´t. In case of the Sovereign and me thinks of most newer Citations, it says Flight Safety International AND Cessna on both checklists and I was verbally informed by a memnber of Team Sovereign that FSI has a major stake in writing these checklists together with Cessna.

[tommoutrie]

Which rule? Where is this rule about not taking flaps before 400 feet?

Let me stick my neck out further. Some of the responses are concerned that retracting the flaps at the manufacturers recommended speed may be flirting somehow with the net take off flight path and therefore putting you in a sticky situation should you actually lose an engine.

The opposite is true. If you DONT take the flap up and continue to accelerate you are potentially putting yourself in the area where you don't know what gradient you can achieve.

Here's why. Lets use V2+10 as the generic flap up speed because I can't be bothered to type all the caveats.
V1, rotate, take off, positive rate, select gear up, accelerate to V2. So far it makes no difference whether you lose an engine or not - we do the same thing. However, if you have lost one you remain at V2 (or slightly over because if you go below V2 the drag markedly increases because thats the side of the LD curve you're on which is why we climb at V2 to V2+10). We don't climb on one engine at V2+30 or 40 because.....

THE DRAG IS HIGH BECAUSE OF THE FLAP

Does anyone disagree with that bit?

Ok so lets say both engines are still running and we accelerate from V2 to V2 +10. Now you are at the point where you can take the flap up. The reason you can do this is the manufacturer says this is the time where changing characteristic of lift and drag is least - look at the curves. The LD curves for flapless and flapped are closest at this point. If you keep accelerating with flap then the drag just keeps increasing - you don't get a busting lot more lift out of the wing. If you take the flap where the manufacturer suggests, the pitch change is smaller and as you don't have the increased drag you accelerate/climb a bit better. You use less fuel, you get away from the ground better. And if you do lose an engine you are in a clean aeroplane thats climbing better and easier to fly.

There is no downside.

The idea that we take off and have to make sure we are above 400 feet before retracting the flaps is a myth. The idea that we may somehow move the wrong lever and that would be a disaster is just rubbish otherwise we would have decision altitudes on approach which reflected that.

Why make a call for flaps based on anything other than speed - speed is all that flaps care about! Why complicate the call for the PM and require the call to be conditional on two parameters?

Whats happened over the years is that operators have become confused by teaching from FSI and others, missives regarding noise abatement requirements, and attempts to standardise what happens on a normal take off compared to what happens if an engine fails.

The answer to the last problem is they have always been the same - its willie waving nonsense thats make it complicated. You take off, if you get to V2 you climb, if you get to V2+10 you raise the flaps. If you have lost a powerplant or, indeed, if you cant accelerate and climb adequately for any reason, you can use a pre-arranged acceleration platform to do that and raise the flaps there.

so now I've gone further and suggested that what most people do doesn't actually comply with the rules.. now everybody will hate me.. whats the number of that truck driving school, truckmaster I think it is...

[His dudeness]

Okay, I hate you now. Satiesfied?

Right, don´t mention it.... ;)

The idea that we take off and have to make sure we are above 400 feet before retracting the flaps is a myth. The idea that we may somehow move the wrong lever and that would be a disaster is just rubbish otherwise we would have decision altitudes on approach which reflected that.

Well, it might a myth, BUT in my airplane its in the official checklist/AFM.

And even if we have a tad more drag between 0 and 400agl, I´m comfortable with the idea of having some time to observe, check and act before doing anything even on a non-event departure...

[tommoutrie]

well that fair enough - its your plane. What do you do with the flaps on a go-around? Do you fairly smartly go from flap land to whatever the take off setting is or sit about for a bit, just in case? The difference between taking the flap passing V2+10 and waiting for 400 feet is probably not much in terms of drag but I think its important for pilots to make flap settings for the right reason and that reason is the speed, not the height.

and... where the hell does it come from!! If its so ingrained that Flight Safety are now writing checklists in conjunction with Cessna the thick will plotten!!

..just saying..

[tommoutrie]

my grand is still safe.. ;)

[Kak Klaxon]

FAR 25 section 111, used notes please in a bag marked Kak to be left at TAG Farnborough.

[cldrvr]

JAR/FAR 25 certification states no config changes below 400 AGL, (other than prop feathering if my memory serves me right)

Send the grand to a Cancer Research UK please.

[cldrvr]

Come on guys, FSI would not unilaterally make things up in their training.

[cldrvr]

Oh and the 1,500 is the end of the takeoff path if anyone wonders where that number comes from, unless the enroute altititude is below that, can't think of an airport that has an enroute segment below 1,500 but wait to stand corrected on that one.

Let me correct myself here.



Takeoff path.

“The takeoff path extends from a standing start to a point in
the takeoff at which the airplane is 1,500 feet
above the takeoff surface, or at which the transition from the
takeoff to the en route configuration is
completed and Vfto is reached, whichever point is higher"

[tommoutrie]

FAR 25 section 111 and JAR 25 certification are both in the event of the failure of the most critical powerplant. It says so right at the top. Also, it makes sense. If all the engines are running you can raise the flap at the flap up speed. This is where the confusion comes from and is why FSI teach it so badly. They spend all their time teaching people to fly away with one engine out and virtually no time at all teaching people to take advantage of all them jets..

This is the reason that no manufacturer mentions 400 feet during an all engines operating departure.

Is a two way bet and I'm two grand up now. Cheque going to the dogs home.

[cldrvr]

FAR 25 section 111 and JAR 25 certification are both in the event of the failure of the most critical powerplant...


No it is not.

[His dudeness]

Do you fairly smartly go from flap land to whatever the take off setting is or sit about for a bit, just in case?

Its a mood thing, you know, if feel like doing it quick, then... :)

Apples and Oranges....going from Flaps 7° or 15° to 0°, or 35° to 15°....from 35° to 15° you more or less just reduce drag, from 15° or 7° to 0° its more about lift, IIRC...

And in the checklist is says:

All Engine Go-Around
1. Go-Around Button (either throttle)..................... Push
2. Throttles ....................................TO Detent
3. Airplane Pitch Attitude........................ 7.5°Initially
(FD go-around command), then As Required
4. Flaps............................................ 15°
5. ClimbSpeed..................................... VAPP
6. LandingGear ......................................UP
And here we go again:
7. Flaps........................... 0°(VAPP+10knots and at or above 400 feet AGL)
8. Airspeed..................................As Required
9. Throttle ...................... MCT Detentor As Required
10. YawDamper................................ As Desired
11. Autopilot ................................... As Desired

BTW, from 7° to 0° takes ages, even If I´d be half as alert as you are and change the setting ASAP (say at 200ft minimums), the flaps wouldn´t be in below 1000-ft...

[gaunty]

My Friends

Don't get confused, it's 400/1500 ABOVE THE TAKE OFF SURFACE.

We like FSI insist that after V1 commit, the crew "figuratively" or mentally sit on their hands until you get to 400ft ABOVE the take off surface, from a certification viewpoint there is no requirement for any action including EFATO actions and it reduces the opportunity for fumble thumbs and provides for an orderly, thoughtful and disciplined reaction.

The certification rules and the jet turbine now provide the opportunity to avoid a reactive response, denied Part 23 pilots and the old CAR 4 types where quick but accurate responses often meant the difference between hero or zero.:{

Tom, thanks for the stimulation but I'm not yet sure about who owns the grand. :cool:

[tommoutrie]

hey... that wouldnt be a flight safety checklist would it?

and CLdriver

straight out of the FAR's, 25.111, I draw your attention to note 2 in the conditions for the net take off path..

(a) The takeoff path extends from a standing start to a point in the takeoff at which the airplane is 1,500 feet above the takeoff surface, or at which the transition from the takeoff to the en route configuration is completed and VFTO is reached, whichever point is higher. In addition --

(1) The takeoff path must be based on the procedures prescribed in §25.101(f);

(2) The airplane must be accelerated on the ground to VEF, at which point the critical engine must be made inoperative and remain inoperative for the rest of the takeoff; and

(3) After reaching VEF, the airplane must be accelerated to V2.

(b) During the acceleration to speed V2, the nose gear may be raised off the ground at a speed not less than VR. However, landing gear retraction may not be begun until the airplane is airborne.

(c) During the takeoff path determination in accordance with paragraphs (a) and (b) of this section --

(1) The slope of the airborne part of the takeoff path must be positive at each point;

(2) The airplane must reach V2 before it is 35 feet above the takeoff surface and must continue at a speed as close as practical to, but not less than V2, until it is 400 feet above the takeoff surface;

(3) At each point along the takeoff path, starting at the point at which the airplane reaches 400 feet above the takeoff surface, the available gradient of climb may not be less than --

[tommoutrie]

everybody is happy with what happens if the engine fails at V1 because thats what we all spend a load of time learning about. But we don't properly consider what happens if it fails a bit further up the take off path and often don't even have figures for what happens if, god forbid, all the engines keep running.

If an engine fails above the flap up speed it doesnt matter where you are in the takeoff path the airframe should be clean. Thats part of why this matters. Lots of folk are well above and are still dirty. Often they have reduced the power a bit to contain the climb and if a powerplant then fails they are well into the draggy bit of the curve. Because they've reduced the power to hold the deck angle and keep the climb rate sensible they now have to set max cont and focus hard to get the aircraft back to V2 to make sure they are climbing properly. Where are they on the vertical SID profile? nobody knows..

If they are clean at the point where it fails they still have to set max cont on the remaining power plant but only have to come back to V2+10 or in reality, Venr. They will climb better than they would flapped and are in a better position because they had to reduce speed by a smaller amount and therefore incurred less of a drag penalty.

There is no downside in doing it correctly!

(be honest, has this got you thinking..)

[cldrvr]

Tm, don't have the regs to hand here so can't give you the exact reference until later tonight.

Have a look at the AMC, I am 99% sure on the top of my head that there is a reference to all engine operating in there with regards to the 400'.

If you don't have a copy to hand, I will post the reference later here.

[Pilot DAR]

I went through this discussion with a company pilot who was right seat to me during Caravan flight testing I was doing. The company pilot was horror struck when I retracted the flaps from 20 to 10 as I accelerated through the appropriate speed, irrespective of altitude - on a deliberately flat takeoff. He was so shaken by this, he had trouble expressing his concern. I bit shaken myself from his reaction, I went back to the Flight Manual, to be sure I had no missed something important during my first read. Nope, no reference to a minimum AGL for flap retraction, so I had flown the aircraft within the terms of the Flight Manual. He was annoyed when I pointed that out to him. "But... but.. what if you'd had an engine failure...?". "Well, I'd rather enter a glide with less drag, so if the speed is right, I would rather have the lesser amount of flaps extended. I can re-extend them any time I want". He did not agree, but could not present an argument to this logic either. He decided to stop his resistance when I pointed out that the Flight Manual states for a balked landing (which is kind of like a takeoff) to retract the flaps to 20 right after you apply power - not wait for any particular altitude before a configuration change!

The quoted FAR is a design requirement, it is not an operational regulation. The aircraft must demonstrate the stated capability, that FAR is not telling you that you have to fly it that way, just that it can be done.

If a Flight Manual tells you that you must or should, then you should. If the person who owns the plane says "fly it this way" then you should if you want to keep your employer happy. Otherwise, fly the plane safely, operate the flaps within the limiting speeds, and select the flaps as you require them.

[tommoutrie]

is nobody else seeing a common thread here...

how the hell did pythagoras convince the people that the earth was an oblate spheroid? oh wait... that happened a thousand years later when Magellen sailed round it..

why is there a slavish addiction to a rule that's painfully obviously rubbish just because its what we all thought was right? This is a bad industry to just blindly accept what you're told. Its important to actually understand.

Still up for the bet.

[His dudeness]

Where are they on the vertical SID profile? nobody knows..

The only that matters is that they are above the REQUIRED profile. (the OEI profile usually)... Which they certainly are if they had to reduce power to keep deck angle & ROC 'sensible'.

By how much I´m above a required altitude is not really of interest, IMHO.

They have enough speed to come back gently to V2 whilst adding power back to MCT.

Q.: what do you do if you need, say, a 6% gradient to 7000ft above the airport, you depart, collect your flaps at 400ft, set MCT & accelarate in the climb and then eat a goose at 2000ft. Lets say your at 160 KIAS at the time, V2 would be 116 and Venr 180.

Do you accelerate to Venr or pull back to V2 and reset flaps? Or V2 without flaps? Or just stay at the present speed?

[Kak Klaxon]

I give up. :ugh: it's worse than talking to my teenage daughters.

[tommoutrie]

You do exactly what it says in the manual. You should have taken the flap at V2+10 (is it for the soverign?) so you should be clean. You are above 1500 feet so you confirm which one had gone bang, select MCT on the other one and an appropriate pitch for Venr or dial it into FLC and continue the climb for 7000 feet.

The airframe climbs better clean than it does with flap. You take off with flap to reduce the take off roll and keep the groundspeed down for the tyres and to make sure the brakes can cope with an RTO. Once in the air and above the speed that you can retract them you get rid of them because now they are only producing extra drag.

If this stuff was taught properly it wouldn't even be a question.

[tommoutrie]

on the bright side, if we sort this out now we don't have to think about it when it happens!

out of interest, does anyone actually agree with me?

[tommoutrie]

apart from klaxon's kids?

[Empty Cruise]

Tom,

I think that through our combined sheer disbelief, FSI indoctrination or desire to retire with licenses still intact, a majority here might well be against the motion.

There seems to be 2 distinct issues at play here:

1) Operators flying all-engines operating with a fixed pitch and getting alarmingly close to VFE before retracting flaps on a normal departure.

2) The aerodynamic efficacy of the aircraft operating at V2-V2+10 with TO flaps vs V2+whatever clean

Now, issue 1 - can deffo see where you are coming from. Have flown everything from B737, CL30, EMB Legacy and CL850, and in all of these airframes, "Gear UP - Level Change" has produced acceptable attitudes, V2+15-20-ish and acceptable ROCs. Fixed pitch is bad for noise, fuel, path and turn radius - so am fully with you on the idea that on a normal TO, flying V2+80 and flaps TO is a kaka idea.

Issue 2 - still not buying it. From an aerodynamic POV you might very well be right, but with no way of making the manufacturer accept your evidence. They all have 2 ways of climbing OEI:

1) V2 and Flaps TO (or back to V2+10 if failure occurred after this speed)
2) Vfto and Flaps 0

Now, apart from waving Ockhams Razor at you - suggesting that the simplest explaination for OEMs chosing Vfto as your clean climb-speed because this is the most effective gradient speed, thus having the best performing and thus best selling aircraft they can - I simply must disagree with the idea of flying the aircraft in a radically different configuration than the OEM tells you to, especially just after losing one engine. This apart from the arguments stated in my previous post...

If the G650 AFM says gear+flaps up at the same time, then so be it, and that aircraft then needs to be flown accordingly. However, if it is just the 650 checklist that states this, then this is merely the sequence you check things in, not necessarily indicating a temporal relationship between when you legally can retract the gear, respectively the flaps. On the 850 checklist, "Gear and Flaps" is one check-item but by no means one do-item ;-)

It may be more efficient going clean @ V2+whatever - but why would I do it? I check for each and every departure that I can clear all obstacles using the AFM speeds and configuration, so I would gain nothing by going down the path you suggest. I cannot lift more mass out of a given runway, but by using non-standard procedures I leave myself wide open to attack from lawyers, to career-ending rumours about my person and ridicule from my peers.

In other words - you may have an aerodynamically point, but from an operational point it's a non-starter.

Payment by cash or cheque accepted :E

[BizJetJock]

Sorry, Tom; you're down 2 grand.

First, it's interesting that you keep saying everyone's doing it (in your opinion) wrong because FSI & co have been teaching it for years. The reality is that it's only recently that they've started to teach it after years of pressure to correct their previous errors. They used to teach all sorts of strange things that were not as per manufacturer, and have the court cases to prove it!

Second, a lesson in aerodynamics; V2 is most certainly not the best angle of climb speed. It is the minimum speed for climbing out following an engine failure at V1. On swept wing jets, Vxse is between V2+10 and 20, which is why many manufacturers' advice for an engine failure above V2 is to slow to V2 + 10 or + 20 depending on the type. It is also why when you get into airliner size machines they give you the figures for the option of trading runway length for improved climb by increasing the speeds.

I agree entirely with you that flap retraction is a function of speed, not height. I also agree, I have never seen an AFM or manufacturer's checklist that gives a height, although many say "not below 400ft". The significance of the 1000 or 1500 (or even 400 for those so inclined) is that it is the trigger to start accelerating for flap retraction. The reality is, though, that most bizjets have so much performance that you are normally already past the minimum speed and so can retract the flaps immediately. I have seen crews cockup in the sim when heavy, hot & high due to this not being the case, but just because crews don't understand the SOP (usually due to poor training) doesn't make the SOP wrong.

So why is the SOP as it is? There are two reasons, both of which have already been posted.

The first is NADP's. All EU-OPS operators are required do do them. So before we go any further, anyone retracting flaps at 400' on a European commercial operation is operating illegally. In this context, you are actually better off having some flap down, because the drag and the pitch attitude change of flap helps with the issue of body angle. 15 to 20 degrees is no problem, but more does start to be uncomfortable in the back particularly for pax in rear facing seats.

The second is the engine failure in the climb case. All twin engined jets will do a far better gradient on two engines even at a much higher speed than they will OEI. For example, at 200 knots 2000fpm is a 10% gradient. That is off the scale for most aircraft OEI. So in the event of an engine failure in the climb you are already above the NTOFP. During the period of reducing speed to V2+10 you will be climbing better than at the steady V2 had you had an engine failure, and when steady at V2+10 you will still be climbing better, see above. So you have guaranteed your obstacle clearance.
However, if at some point before the engine failed you have retracted the flaps, while you start off in the same position you rapidly move into no man's land. You mention the Challenger; there is no second segment speed clean because flaps up is not an approved takeoff configuration. So what speed should you fly? And what is the performance at that speed? If you fly at Vfto/Venr or whatever the manufacturer calls it, you may or may not have to accelerate to reach that, and the gradient may or may not be better than V2 with flaps. Most of the time it is, but not always. And the passengers are not paying for "most of the time" or "probably" - they are paying for definite answers.

So to summarise, leaving flap retraction to 1500ft or similar has advantages in being the approved noise abatement procedure and guaranteeing obstacle clearance in case of an engine failure, with the bonus of the commonality of procedures between normal and OEI ops also mentioned. So why do it any other way?

Interestingly, if you read D.P. Davies, the airlines were having this discussion 30 years ago. It's nice to know we're at the cutting edge of the industry!

So, Tom, you can send the cheque to me made out to the Campaign Against Sobriety and Hunger (C.A.S.H. will do!):ok:

[Pilot DAR]

out of interest, does anyone actually agree with me?

Yes, I do.

I spent more than an hour flying my amphibian over the water yesterday, and obeying the 400 foot "rule" for flap retraction, I would not have retracted them the whole hour, as I did not get higher than 200 above the water....

The first is NADP's. All EU-OPS operators are required do do them. So before we go any further, anyone retracting flaps at 400' on a European commercial operation is operating illegally.

Is that any flaps up at all (don't touch the knob)? Or just the last flaps to a clean wing? I do hope that if flying a balked landing, they'll let you get the flaps from "landing" to "takeoff" at a lower altitude than that, or it could get exciting in some conditions!

[BizJetJock]

Sorry, the curse of acronyms! NADP's = noise abatement departure procedures, so not relevant to balked landings.

And this whole discussion is about transport style jet ops - not real flying! I don't think I'd stay employed for very long if I did a whole trip below 400 feet, but it might be worth it....:E

[I.R.PIRATE]

Which brings us to another quandry.

On the aircraft I currently fly (G-IV-SP)

The manuals all state flaps up not below 400ft. Although I must admit that I found an earlier (1999) CAE training checklist stating : on positive rate of climb - gear up , flaps up.

However, if we work it backwards slightly, on an all engines operating go-around, there is nothing about a 400ft min for cleaning up, it just clearly states flaps up at V2+20. Which brings us back to Tom's question of why the 400ft 'limit' is there in the first place, if we are expected to clean up the flaps at V2+20 on a go-around. Why then not on a normal departure?

In the case of the G-IV its actually much of a muchness, in that on a normal all engines departure, selecting gear up on positive rate of climb and waiting for the lights to go out, leaves you at just about 300-400ft, on speed, ready to retract the flap. Thus we are quite happy to stick to the prescribed 400ft flap up, FLCH call as prescribed during training, as its near as dammit to lifting the flap as soon as the gear is confirmed stowed away.

[tommoutrie]

ok Emptycruise and BizJetJock you seem pretty sure of your ground.

Would you like to actually take the bet?

I'm perfectly happy to leave it at a grand but if you're not so sure we can make it a pint. Either way, witnessed by all and sundry.

:ok:

[tommoutrie]

By the way, my point, once again, is that we should do it exactly as per the AFM. Nothing I've suggested at any point in this thread suggests otherwise and furthermore, I'm pretty sure that most business jet operators don't fly the take off as per the AFM. I kind of think we should.

Anyway.. bet on? you can name the stake.

[BizJetJock]

Haven't got time to post the docs, but I've just checked the AFM's of the CJ2+ and the CL601 (since you mentioned types). Both of them, in the "normal procedures, after takeoff", just say "Landing gear - up; flaps - 0". So as far as lawyers are concerned, either way of doing it is complying with the AFM.

I'll call that a beer.....

[DA50driver]

On the first generation jets with water injection 400' was used to allow for a level off and acceleration to clean speed.

They wanted to ensure that they would attain the required speed before the water was consumed.

We still use it today for normal ops in our G450/550, but we have so much power it's not required anymore. In the event of an engine failure we climb to 1500' or a safe obstacle clearing altitude prior to acceleration and flap retraction. (With two donks running and flaps 20 we would overspeed the flaps unless we had a 40 degree deck angle).

[tommoutrie]

DA50, what do you do then on a normal take off? when you select flaps up? What speed in particular?

[tommoutrie]

Hello Emptycruise

Do you mind if I include a couple of bits of what you posted so that I can reply to them?

1) Operators flying all-engines operating with a fixed pitch and getting alarmingly close to VFE before retracting flaps on a normal departure.

Yes this is what I'm particularly concerned about and has been the thrust of the post from the start.

2) The aerodynamic efficacy of the aircraft operating at V2-V2+10 with TO flaps vs V2+whatever clean


I am certainly not advocating climbing clean at V2+whatever. I'm suggesting that if we are not doing a noise abatement departure we take the flaps up once we are above the AFM flap up speed and continue to accelerate to at least Venr and then onto a sensible initial climb speed for the aircraft.

Noise abatement causes specific problems for high powered business jets so we could debate these as well if you like.

Issue 2 - still not buying it. From an aerodynamic POV you might very well be right, but with no way of making the manufacturer accept your evidence.


I am suggesting we climb the aircraft exactly as the manufacturer suggests.


1) V2 and Flaps TO (or back to V2+10 if failure occurred after this speed)

This doesnt make any sense. All engines operating, no manufacturer suggests that for a normal departure we climb at V2. In the case of an aircraft where the flaps come up at V2+10, the manufacturer expects us to raise the flaps at V2+10 (which hardly anyone does). If we are at a speed over V2+10 and clean we would hold that speed. If you were at a speed appreciably above that you would increase the pitch to reduce speed to V2+10 (although in practical terms it may make more sense to simply reduce the speed to Venr). This IS what the manufacturers intend us to do. The aircraft will climb more efficiently clean than in the flapped condition. The whole point is that if the failure occurs before the flaps are raised that we do not have enough excess power to accelerate and climb (well thats where the theory comes from) and we have a demonstrable net take off flight path if we delay the acceleration to a known platform. That is not always 1500 feet. There are a number of other limitations which may mean the available acceleration platform is lower - one of which is the time you have available at max thrust on one engine.




Now, apart from waving Ockhams Razor at you - suggesting that the simplest explaination for OEMs chosing Vfto as your clean climb-speed because this is the most effective gradient speed, thus having the best performing and thus best selling aircraft they can - I simply must disagree with the idea of flying the aircraft in a radically different configuration than the OEM tells you to, especially just after losing one engine. This apart from the arguments stated in my previous post...

Nowhere am I suggesting flying the aircraft in a manner which is not consistent with the AFM. I am suggesting that the most common way that we are told to operate these aircraft is not in accordance with the AFM. I am directly suggesting that the majority of SOP's do not understand what the AFM actually says. I am suggesting that all engines operating it is ridiculous to use a height to trigger whether or not to raise the flap. It doesnt exist in the regulations, it doesnt exist in the FAR's, it doesnt exist in the JAR's and its been incorrectly interpreted from the situation where a powerplant fails.

If the G650 AFM says gear+flaps up at the same time
I'm absolutely certain that the 650 will have a flap up speed, V2+whatever, and it tells the crew to take the flap up at that point. So does every other aircraft, yours included (what is it by the way and I'll look it up).

It may be more efficient going clean @ V2+whatever - but why would I do it? I check for each and every departure that I can clear all obstacles using the AFM speeds and configuration, so I would gain nothing by going down the path you suggest.

For all the reasons stated previously, ie noise, fuel burn etc. Also, if you are saying you fly every single departure to 1500 feet without the speed going over the flap up speed then fair enough but if you exceed that speed (in all honesty it has to be by a bit) then you are creating extra drag and degrading your all engines operating flight path. Thats simply bad airmanship because if you do lose an engine you have to pitch for longer to get back to V2 to V2+10 (and just that pitching causes a fair amount of drag so the longer you pitch, the more drag you make) and when you get there you don't climb as well as you would if you were a bit over V2+10 and clean. Because that is where the manufacturer intended you to be.

I cannot lift more mass out of a given runway

True but because you haven't burned it you do carry a little bit more fuel to altitude and there is absolutely no penalty. You burn that fuel churning up the air with your flaps!

but by using non-standard procedures I leave myself wide open to attack from lawyers, to career-ending rumours about my person and ridicule from my peers.


In fact, this is my point. Although its very unlikely, I honestly believe that the slightly confused way we are taught and the lack of understanding it leaves the majority of pilots with means that it is the vast majority of us that are operating outside what the manufacturer has intended. Perhaps you included!


In other words - you may have an aerodynamically point

you might mean an aerodynamically correct point and I do

but from an operational point it's a non-starter.

really? why?


Once again, please show me the business jet AFM which says what we are all commonly doing is correct. I'm actually not saying it doesnt exist, but I am saying that for all the types I've ever come across it is clear we are not doing it correctly. What type do you fly EmptyCruise?

[tommoutrie]

one thing that I'm going back to my university books for is the relationship between V2 and Vx. V2 is a computed speed which cannot be less than Vs. Vx all engines operating can be well below Vs depending on available thrust, take off mass, loading, airfoil section, all sorts of things. Vx OEI (Vxse would discount all the three and four engined pilots out there and I'm all about inclusion) is always higher than Vx all engines (provided all the other considerations remain the same) but from memory is usually very close to V2. Vy is usually a bit above V2.



I'm currently buried in Roksam Airplane Aerodynamics and Performance to try to work out the answer. Taint easy.. In fact, that one I will search the teccies corner for..

[provo]

Really good discussion.

i wonder if the 400ft is more about getting out of ground effect, getting some distance between you and the ground in the event of windshear etc and establishing a stabilised flight path before thinking about touching some buttons. So possibly more about the possibility of human error close to the ground than anything else.

[A Pandy]

Tom,
First off let me just say that I tend to agree with your argument and would consider myself to be on your side. However having just finished school on the G650 I can assure you that in the AFM and the Operating Manual there is no speed mentioned in relation to raising the flaps. For both flaps 10 and flaps 20 take-off the climb checklist calls for gear up and next flaps up.
For interest sake it is FSI that has the 400' call included prior to raising the flaps.

[mutt]

A Pandy, a similar statement is in the older Gulfstream Manuals, where Flap retraction is based on speed and not altitude. However have Gulfstream made any software available to you, to prove that you can clear obstacles in the takeoff flight path with all engines operating?

Mutt

[tommoutrie]

Well that's very interesting for the 650. Is there a flapless take off option?

[JonDyer]

Well I think he's right - and I know him so that really is saying something.

Some people here (no names, no insult intended and no personal attacks) just are not reading what he's saying (he never once advocated flying outside the AFM instructions) or just cannot consider that their SOPs may be based on folklore.

He is being as clear as he can be - it makes sense to me. It surely is self-evident that flap retraction is unrelated to height?

As for those who feel more 'comfortable' not touching levers below 400ft - what about the gear? Do you leave that down? Climb-power? Mode Select? Does it all hang out until AA or is it just the flap lever you won't lay hands upon?

(Just joking - no fight wanted - this really has been an unfeasibly good-natured 6 page thread)

[mutt]

It surely is self-evident that flap retraction is unrelated to height? The flaps have no idea what height you are at, so they dont care :):)

But again, please don't look at the flap retraction in isolation. Firstly, why do you want to rush? Secondly, how can you prove that you will clear the takeoff obstacles? There is nothing in the AFM for all engine obstacle clearance as its not required by regulation?

As an airline, we increased the 400 feet to 800 feet and took the associated weight loss, we use 1000 feet for all engine, that philosophy was carried over to the corporate fleet.

Mutt

[JonDyer]

Firstly, why do you want to rush?

I'm not fighting his battles for him but I can't help but wonder how positing an entirely arbitrary limit is somehow 'better' than operating in accordance with aerodynamic limitations. It's just trading one belief for another - that's politics 'innit?

There is nothing in the AFM for all engine obstacle clearance as its not required by regulation?

I must be misunderstanding you here because there are certainly climb gradients for flap zero OEI ops. How can two engines not deliver better performance? If they didn't we might never meet our SID limits on a normal day.

[tommoutrie]

Hello Mutt

Same as above, hope you dont mind if I cut and paste your original post.

Firstly, why do you want to rush?

I'm not suggesting you rush. I'm suggesting that, in the same way as we note "positive rate" and call for gear up that we say "V2+20" and call for flaps up. (its V2+20 on my plane). When the PM calls "Positive Rate" you don't wait to climb to 400 (or 800) feet because you might possibly move the wrong lever, you get rid of the drag. Why is the same not true with the flap?

Secondly, how can you prove that you will clear the takeoff obstacles?

I have complied fully with the AFM therefore I will clear the close in obstacles and everything in the net take off flight path. I was all engines operating to V2+20 and continued the climb at a gradient in excess of the PDG. At any point I could have lost an engine and remained above the PDG. I dont think the calculation is as easy if you go busting through the flap up speed and leave them down thus degrading the climb with drag because thats not what the AFM says.


As an airline, we increased the 400 feet to 800 feet and took the associated weight loss, we use 1000 feet for all engine, that philosophy was carried over to the corporate fleet.


On what basis did you do that? Is it in the AFM? Seems amazing to me that operators make these sweeping decisions and there's no basis in aeronautical logic. Which aircraft types is this for? I don't understand how these policies get written and over-ride the manufacturers manuals for the planes.


I'm going to try to arrange a meeting with Flight Safety at some point this week to chat about this. I've also been promised a call back by one of Bombardier's guys tomorrow. How about I report the result of those conversations on here when they happen?

[tommoutrie]

sorry mutt - read my post and it reads like I'm calling your department idiots and I'm really not. I think this kind of potentially flawed logic is very widespread indeed and I don't know why its happened. Lets see what the boffins at Bombardier and Flight Safety come up with - if a lowly pilot bod like me can get through to them..

[mutt]

Yep it's in the AFM, remember 400 feet is a minimum not a maximum. We do it or have done it for....
B707/737/747-100/200/300/400/ b757, B777
Airbus 300,320,330,340
MD90,11
Embraer 170
Gulfstream 3/4
Falcon 900/7X

All manufacturer approved and is a default in their software. :) this is also the way that crew are trained in Flight Safety :)

Mutt

[B200Drvr]

Tom
At what speed or height do you think we should start retraction of the flaps for a standard all engines operating non noise abatement departure?

[tommoutrie]

exactly as per the AFM. On my aircraft the AFM says at V2+20. Height is not a condition for flap retraction. It doesnt matter if you are all engines operating or one engine inop. Its exactly the same. Retract the flaps at V2+20. If you can't accelerate to V2+20 in the climb (perhaps because a powerplant has failed) then use a pre-arranged level acceleration platform to pitch to level flight and accelerate there to V2+20 then retract the flap to get rid of the drag and accelerate further to Venr.

Who was throwing Occams razor at me earlier? Surely the method above is simpler that all that other fannying around because its exactly the same regardless of whether you lose an engine or not. Take off, call of "positive rate" - put the gear up and pitch to 15 degrees, accelerate to V2+20, call of "V2+20" - put the flaps up. If you have lost thrust and cant accelerate to V2+20 in the climb, use the Acceleration Altitude agreed prior (1500 feet) and speed up there.

as that bleeding meerkat says, simples!

[tommoutrie]

(next threads gonna be noise abatement and all the bull**** and mystery that goes with that!)

[First.officer]

Okay, have to agree that for all donkeys working i agree that the Flap Retraction Altitude is a hang back to some unknown reason that we all do without really questioning it, and that 400ft agl is most likely chosen because it coincides with the OEI acceleration altitude to get to V2+10 and clean up etc., etc. - i know it's not correct, but what sort of time (seconds) does it take on average i wonder to get from V1 to V2+10 etc., etc when compared to reaching 400ft agl?? probably about the same in my CJ ??

[B200Drvr]

exactly as per the AFM. On my aircraft the AFM says at V2+20. Height is not "a condition for flap retraction. It doesnt matter if you are all engines operating or one engine inop. Its exactly the same. Retract the flaps at V2+20. If you can't accelerate to V2+20 in the climb (perhaps because a powerplant has failed) then use a pre-arranged level acceleration platform to pitch to level flight and accelerate there to V2+20 then retract the flap to get rid of the drag and accelerate further to Venr.

Who was throwing Occams razor at me earlier? Surely the method above is simpler that all that other fannying around because its exactly the same regardless of whether you lose an engine or not. Take off, call of "positive rate" - put the gear up and pitch to 15 degrees, accelerate to V2+20, call of "V2+20" - put the flaps up. If you have lost thrust and cant accelerate to V2+20 in the climb, use the Acceleration Altitude agreed prior (1500 feet) and speed up there.

as that bleeding meerkat says, simples!"

With that in mind, what if you pass V2 +20 while your gear is in transit, ie the lights have not gone out, do you still select flaps up?

[BizJetJock]

I think the root of the problem is that you are confusing a minimum with an instruction. V2+x (depending on type) is the minimum safe speed for flap retraction, in the same way as Vfe is the maximum for extension. Do you always extend flaps at Vfe as you slow down?

Good luck with a meeting with FSI; unfortunately a large part of the problem is that they don't understand it either so you will not get an authoritative answer even if they sound definitive.

Bear in mind that the checklists are written as a follow up to you having done everything, so by the time you get to reading a checklist which may or may not mention a height or a speed you will be long past it.

That also opens the can of worms of why are they still teaching read and do checklists decades after manufacturers changed to scan flows and challenge and response?

May be able to add some more definitive references later, but I need to go and earn a crust now!;)

[JonDyer]

I think the root of the problem is that you are confusing a minimum with an instruction. V2+x (depending on type) is the minimum safe speed for flap retraction...

He's not confused at all. He is saying that it *is* an instruction and FWIW I think he's right.

He is saying that failure to comply in a timely manner degrades flight-path performance, burns fuel and increases noise footprint.

He is not advocating going against anything written in the AFM.

(Incidentally since we are all professionals here and since we have all known since PPL days that the AFM is the word of God herself, can we stop the straw-man arguments about "test-pilot" flying? Even the gashest cowboys I have ever shared a Cessna with know not to argue with the AFM. )

He is claiming - suggesting even in his Tom-like manner - that the height restriction is arbitrary, unnecessary, wasteful, and possibly came out of the mists of time as tribal-knowledge and has no place in modern ops.

It's a point of view that no one has properly knocked down though some have made balanced well-reasoned and informed arguments against.

Not much like a real PPrune thread then.

This should be locked.

[BizJetJock]

OK, I'll go with the Challenger 605 since it is one of the types I am current on, and the other - the CJ - is not a Part 25 aircraft so really doesn't qualify for this discussion.

So let's start with the AFM.
All it says in the normal procedures section is the After Takeoff Checklist where it just says:

O. After Take-Off Check
(1) LDG GEAR lever .............UP
(2) FLAPS ................. Set to 0°
(3)

No mention of heights or speeds.

In the FCOM1, expanded normal procedures, it says:

G. After Take-Off Check
(1) Landing gear ........................................................Chec k retracted.
NOTE
During normal operations, landing gear and flap indications are normally occulted (removed
from EICAS) when the landing gear are stowed and the flaps are up.

At not less than VFTO + 5 KIAS:
(2) Flaps....................................................... .................. Set to 0°.
(3)

Note it says "not less than".
Also bear in mind that this is the checklist, which is intended to be used as a follow up after the event. The after takeoff checklist should not normally be read until the aircraft is well away from the airport since before that the crew should be concentrating on flying.

So flying a NADP profile in no way conflicts with the AFM, ensures obstacle clearance in the event of an engine failure and gives commonality of procedures between normal and OEI.

As I said before, the height trigger is to start acceleration and is only indirectly linked to flap retraction, and certainly should not be as low as 400ft.

In fact it is the rush to pull the flaps up quickly after takeoff which came out of the mists of time as tribal-knowledge and has no place in modern ops.

Part of the problem is that training providers (I will not single out FSI since there are plenty of others) market themselves as teaching people all they need to know, and most pilots do not make the effort to find out how little the actually know.

A challenge for you all - how many of you have actually read the AFM and the FCOM (or equivalent) from cover to cover? You might be surprised at how much you find in there that is not as you were told in training - even on a factory course!

[tommoutrie]

Hello B200Drv

I feel a bit like I'm being led up the cul-de-sac of shame and slaughter but hey, in for a penny, in for a pound..

I can't think of any particular reason not to select flap up with the gear in transit - there's certainly no limitation I'm aware of. I've got 6 hydraulic packs going full chat at that point. The two that are powering system 3 raise the gear, the other four are split between system 1 and 2 and raise the flap (from memory). Have I missed the point?

Aerodynamically, I can't see why I wouldnt get the airframe clean when Bombardier tell me to.

What have I missed?

[B200Drvr]

Tom,
Not leading you to anything, just trying to find a reason why not to raise the immediately across all types.

[BizJetJock]

the other four are split between system 1 and 2 and raise the flap (from memory)
If you're talking the 601, then memory fails you! Too many beers.....

Flaps are electric on all Challenger 600 series.

[tommoutrie]

bizjetjock - yep thats right, sorry, wasn't really thinking about it and I still dont really understand why its important in terms of a performance discussion. what have I missed? They are completely separate systems. What relation does it have to performance?

(should have remembered that really as the squirly whirly electric cable drive wound itself into a pig tail on one of the 601's I flew not that long ago and I had my head up its chuff looking at it... thats what happens if you answer a question without thinking properly!!)

you could be right, it could be the beer..

[tommoutrie]

Biz jet, you'll upset Cessna if you say it was certified part 23. They voluntarily certified it part 25 for take off and landing and spend a bucket load of cash doing it.

I'm not certain I understand the thrust of the rest of your post. Yes you can fly both noise abatement profiles exactly as they are laid out and not contravene anything in the AFM. Is that a surprise? Thats how it should be. Certainly the 601 flies both profiles without any issue - you do get a pretty consistently high deck angle of approx 20 degrees but I don't really see why that's a problem. You could choose to follow the derate procedure if you want to make it more comfortable (its a bit of a faff in the 601 and my old company couldnt be bothered to include it in the Part B anyway).

[tommoutrie]

Can I bring us back to the central point? Lots of operators (I have worked for 3) have SOP's which encourage pilots to take off with the appropriate flap setting, go well through the speed at which they could select the flap up (sometimes by 50 kts or more) and take the flap up at 1500 feet just because its seen as a flap retraction platform.

Is this what anyone reading this thread does and do people think that's right or wrong?

Also, whats wrong with raising the flap when the manufacturer suggests? Where did a 400 foot height check come from? What I'm suggesting is that it doesnt make sense to have a height check at all for flap retraction. We should have a level acceleration platform available so that we can pitch level and accelerate if required but why is there a routinely accepted height check for flaps?

thats all I'm saying chaps, slightly surprised that everyone seems so negative about it. Do what you like, I don't really care. Tomorrows thesis is on the advantages of flying the ILS inverted so that you see the ground more easily on breakthrough.

[BizJetJock]

Biz jet, you'll upset Cessna if you say it was certified part 23. They voluntarily certified it part 25 for take off and landing and spend a bucket load of cash doing it.

I was really referring to the quality of documentation and procedures rather than the performance - it leaves quite a lot to be desired!

My point really is that the manufacturer doesn't specify, so we have plenty of leeway without contradicting anything in the AFM.

At the same time as EU-OPS operators we are obliged to fly NADP's - it is not optional! (OPS1.235 or if you're getting really ahead then CAT.OP.MPA.130)

And that's before you get into any discussions about engine out procedures. Apart from the esoteric arguments about performance, I have plenty of times in training seen people get themselves into trouble by trying to fly their normal profile following an engine failure. So it is much better to have a procedure where you climb to the same acceleration altitude regardless of number of engines. The only difference is the speed you fly to get there.

And just for clarity, you are flying a speed up to the AA, not a fixed pitch or a VS.

[tommoutrie]

On a noise abatement departure we take off, pitch for V2+15 (or thereabouts), passing 800 feet reduce power a bit, put the autopilot in FLC, LNAV, at 1500 feet wind FLC up to the enroute climb speed of 190, as the aircraft passes V2+20 (normally somewhere around 160) select flaps up, and it climbs away at 190. Then, once clear of the terminal area and typically at around 3000 feet we dial in 250 kts and have a cup of tea.

Normal departure, pitch for 15 degrees, passing V2+20, flap up, when it gets to enroute climb speed 190 or 250 as brief take FLC. Thats not whats in my part B - whats in my part B is daft..

[tommoutrie]

I think noise abatement is quite difficult to fly absolutely accurately and I also think it warrants a proper discussion on here. Its a difficult subject for business jets because hardly anyone does it correctly (well I don't think they do - I could be wrong)

[cldrvr]

Tom, so what would you do if you lose an engine below 400 ft then, just out of interest.

[cldrvr]

Thats not whats in my part B - whats in my part B is daft..


So instead of having a meaningful discussion with your flight ops department, you just do your own thing and ignore your companies SOP's

[tommoutrie]

noise abatement, pitch to keep the speed at V2 to V2+10.

Non noise am already clean so am final segment - pitch for V2+20, when I get to 1500 feet accelerate to enroute of 190, keep max thrust until time limit runs out and set max continuous

What do you do with an engine failure at 400 feet? My arguement is that lots of operators are V2+50 and increasing at that point and I honestly haven't got a clue what their plan is at that point.

[cldrvr]

My arguement is that lots of operators are V2+50 and increasing at that point
and I honestly haven't got a clue what their plan is at that point.


That makes no sense either, how do YOU assure your second segment obstacle clearance if you have already raised your flaps and lost an engine at that point?

[cldrvr]

So why don't you tell me exactly what your profile is

We do not raise flaps before 400' as the regs/OM dictates. You are now on page 8 here trying to justify why you do not need to follow 1) your part B 2) what you have been trained 3) second segment obstacle clearance.

[cldrvr]

Tom, you still haven't answered my question. You ignore the 400', raise your flaps when you like. Now what if you lose an engine, how do you assure your second segment?

[tommoutrie]

Hardly anyone flies noise abatement correctly in business jets - I'm one of the few that tries to. The power to weight and lack of inclusion of derate procedures make it very difficult at anything other than high weights.

As I said before, noise is another thread. Does anyone disagree that the majority of operators do not fly business jets in accordance with either NADP1 or 2?

I'm one of the few that post on here with my real name and actually try to tackle the genuine problems that we face. So who do you fly for, what do you do for NADP1 and 2, what do you do for non noise - give me a typical take off profile on a short european sector at 42,000lbs out of Farnborough for instance.

[tommoutrie]

Cldrvr - just seen your post about raising the flaps

Which regs prohibit raising the flaps before 400 feet? Been asking that since the start of the thread! What is the regulation?

[tommoutrie]

I am assured of obstacle clearance because I fly 2 engines from V0 to Vef and i've done it all according to what the AFM says. I've wasted no energy at all climbing against drag which is NOT the case if you leave the flaps down.

How does anyone else justify it when they climb at up to 190kts with the flaps down?

[tommoutrie]

The aircraft always climbs better clean. The point of the profile with an engine failure at V1 is that you CAN'T accelerate enough to raise the flap AND maintain a sensible gradient. So you cope with the degraded performance until 1500 feet where you accelerate and raise the flap.

Otherwise, whats the point of raising the flap at all?

[tommoutrie]

Look.. I'm not shy of how I operate an aircraft . I'm really happy to discuss it with anyone that can help with the quandry - we can discuss it with the manufacturer, flight safety, flugprestansa, the CAA, whoever. I simply want to know what the conflicting information adds up to.

Its bananas to fly a bastardized version of the OEI profile when you have both engines running - its why the NADP is so tough for us.

[cldrvr]

So you cope with the degraded performance until 1500 feet where you accelerate
and raise the flap.

OK, so you operate your aircraft clean soon after takeoff? What height, roughly do you raise the flaps then, as you don't use 400 ft.

[tommoutrie]

Here is your post

We do not raise flaps before 400' as the regs/OM dictates. You are now on page 8 here trying to justify why you do not need to follow 1) your part B 2) what you have been trained 3) second segment obstacle clearance.

What is the regulation?

Where does it say it in the OM in relation to an all engine operating take off?

What profile do you fly? Do you exceed the flap up speed and if so by how much?

I'm not trying to justify it on page 8 - my argument is exactly the same as it was on page 1. Nobody else has put numbers to what they do. Not one single pilot. Nobody has told me what this regulation is that you've stated exists.
It all adds up to everyone does it like this because they do it like this and nobody ever asks the question.

So I'm asking you - please can you post on here exactly as I have done the profile you fly for noise and non noise departures?

ta..

[cldrvr]

Tom, I have asked the same question 3 times, at what height do you retract the flaps, as you don't use the 400 ft.

[tommoutrie]

to answer your post 152 - I've got no idea what height and I honestly don't care. The flaps can travel because the speed is correct. They don't care what height the aircraft is at and until I see a regulation which means I can't do what the AFM says I think its a good idea to do what the AFM says.

This isnt about one type - its a problem which affects different aircraft in different ways. It was more difficult on the CJ2+ which tended to be right up against the high end of the speed range for the take off flap. Its why I ended up taking off flapless under almost all conditions.

I had a load of pilots tell me I was wrong for doing that too..

[tommoutrie]

I keep answering that. Is anyone else struggling with this? I don't care what the height is - I only care that I'm going fast enough. The height is utterly immaterial.

To help out a bit further. I'm guessing but typically, max take off, probably around 400 feet. Light, maybe 200.

Now. Whats the regulation? What profile do you fly?

[cldrvr]

Light, maybe 200.



Good, we got an answer, now let's assume you are having a bad day and your engine fails at 209 ft. Can you give me your second segment climb gradient from your AFM, use the chart that has the engine failure at 209 ft, clean config.

As I don't know how fast your flaps travel, give me the climb gradient also for flaps in transit, as the engine failed 9 ft after you selected flaps up.

[tommoutrie]

I'm not second segment at that point. I have already accelerated and am climbing at my final segment gradient. Slightly better than that in fact because I'm still using max thrust rather than max continuous. The gradient is better than the flapped climb because I'm clean. The only reason for using the 1500 foot acceleration altitude would have been to get from V2 to V2+20 and then to clean up.

Now

What profile do you fly

What is the regulation?

[tommoutrie]

The portion of the climb where the flaps are transitioning is totally irrelevent which is why it isnt quoted anywhere. The reason it is irrelevent is that I have been all engines operating to that point. My engine didnt fail on the ground at V1 - it failed after a successful take off and climb to 209 feet.

now...

Whats the regulation?

What profiles do you fly?

[tommoutrie]

here's a question for you. Which configuration gives you the better climb? Take off flap, V2 or clean at the flap up speed?

[tommoutrie]

if your answer is V2 and flapped, whats the point of cleaning up at all? Why not climb to MSA in that configuration?

(please don't tell me thats what you would do...)

[cldrvr]

I give up. Tom, you go ahead and go through life being a test pilot on your takeoffs, ignoring your Part B/SOP's and taking procedures from guys you talk to in the bar downroute, I will stick to the regs if you don't mind.

[tommoutrie]

Which regs?

Honestly, please just tell me which regs?

And as for being a test pilot, this is what the AFM tells us to do!

Flight Safety told me today its a company wide SOP and the instructor who I spoke to couldnt tell me any more than that. I'm going to call FS in Montreal later and am still hoping to hear back from Bombardier.

by the way Cldrv, its pretty offensive telling me I'm a test pilot when you are not willing to tell me your company profiles, how you fly them or tell me what this regulation is that you keep believing exists. The relevant sections of FAR25 and JAR25 deal with OEI operations as discussed and quoted earlier in this thread. It is likely that you have confused this with all engines operating. The other regulations which may impinge on this are contained within ICAO 8168 document 2. And I know where that bit is and what it applies to. And it doesnt apply to this!

[tommoutrie]

Where is the acceptable means of compliance reference you were 99% sure exists? I though you were going to send that over the other day too

[cldrvr]

Final attempt here Tom.

You are not guaranteed your 2.7% unless you keep your flaps at TO till 400 and limit your bank angles (and there are some lateral/wind restrictions to take into account also). Raising your flaps before 400 will make you a test pilot if you do have an engine failure as the aircraft, as per the regs only needs to be certified in a single engine/TO configuration until 400 to assure the climb gradient, depending on how many engines are hanging of the back.

Ignoring the 400 ft, means there is no chart available to you in the case of an engine failure if your flaps are in transit/up to avoid that block of flats/school/orphanage in your takeoff path.

Flying is about managing risk, planning for the worst case scenario and flying accurately.

You have shown in your posts in this thread that you don't follow your SOP's, you don't follow your Part B, you keep using terms like "or there about" when telling us how you fly your departures and speeds.

[cldrvr]

Klax was right, teenage girls are easier to argue with......

[tommoutrie]

Dear all

I have deleted a couple of posts which were specific to CLRDRVR because they were a bit personal - I got irritated that he didnt seem to understand what the thrust of this thread is and has accused me of being a test pilot when, in fact, I'm advocating doing things exactly in accordance with the AFM. But there's no need for me to actually be rude which I was so its withdrawn.

However,

read your post 166

yes I do

I am final segment and max continuous. I don't have those charts at home but they are in the AFM because I am time limited to 5 mins at max thrust on one and Bombardier allow for an intermediate level off then a further climb to 1500 feet. I have looked at these charts before and actually forms part of why what I'm saying is correct. Thats how I know I am above the gradient. I didnt need the 1500 foot acceleration platform to get to V2+20 and raise the flap.

now, three things..

what profile do you fly?
what is the regulation?
how about we go through this with a professional for a grand?

[DA50driver]

Flaps up at minimum V2+20 and 400'.

[tommoutrie]

hello DA50

which aircraft is that for and is it in the AFM or is that from somewhere else?
Plenty of other posters are showing that for some types there does not appear to be a 400 foot condition. I am interested to find an AFM with the condition in so that I can work out where it comes from - nobody seems to know!

What aircraft are you flying and what profile do you use and where does it come from?

thanks

Tom

[A Pandy]

Tom,
Have to agree with you here. I don't understand why CLDRVR has to be so aggresive and rude about a very worthwhile discussion.
At the end of the day I fly two types. One says flaps up at V2+25 and the other says flaps up when climb established. Neither type mentions anything about 400'.
Maybe i am flying under different regs to CLDRVR but maybe he could quote what reg mentions the 400' rule. Truly interested to learn.

[I.R.PIRATE]

I actually think the cldrvr deserves the money....:D

> You are not guaranteed your 2.7% unless you keep your flaps at TO till 400 and limit your bank angles (and there are some lateral/wind restrictions to take into account also). Raising your flaps before 400 will make you a test pilot if you do have an engine failure as the aircraft, as per the regs only needs to be certified in a single engine/TO configuration until 400 to assure the climb gradient, depending on how many engines are hanging of the back.

Ignoring the 400 ft, means there is no chart available to you in the case of an engine failure if your flaps are in transit/up to avoid that block of flats/school/orphanage in your takeoff path.

[mutt]

I think this kind of potentially flawed logic is very widespread indeed and I don't know why its happened As I mentioned, your concept of flawed logic was approved by Boeing, Airbus, McDonnell Douglas, Lockheed and Gulfstream, so I guess that they all got it wrong?

I can't fly what they say is correct You are making up your own procedures, and you considered us idiots?

Does anyone disagree that the majority of operators do not fly business jets in accordance with either NADP1 or 2? Nope, we follow the noise profiles.

We have calculated takeoff weights based on the FAR defined flight profile for an engine out. Following your logic and with the approval of the AFM, we can takeoff and retract the gear and flaps almost simultaneously (V2+15-25 weight dependant), so we are at VFS at lets say 200 feet, now an engine fails, what guarantee do i have that i will clear the obstacles in the flight path, you can tell me that I have a better rate of climb at VFS clean, but please provide one chart that allows me to prove that I made a "calculated risk" rather than a "gut feeling"?

We also have specific engine failure procedures with the turn radius calculated on speeds associated with Flaps down, if we go flaps up and accelerate, we then have no guarantee that we can stay in the takeoff cone. So rather than have specific profiles for these airports, we stick with the same non-noise related profile all the time.

Then there is the issue of acceleration altitudes higher than standard due to obstacle clearance requirements, how would you deal with these? Use a different profile?

To me, thats the crux of the matter, its about risk assessment and the only way that i can assess that risk is to follow the profiles published in the AFM.

Mutt

[tommoutrie]

dood.. making it bold and making the text bigger don't make it correct!

Just been on the phone with Flight Safety in Montreal. There is no height restriction in the Bombardier AFM. There is no regulation at all relating to height on an all engines operating take off. As I explained to CLDRVr the reason that the gradient is assured is that by taking the flaps up I am immediately in the final segment climb. With max thrust on the remaining engine its part of the certification that I will maintain the 2.4% (its gross climb by the way not net climb and because theres no level third segment this is easier for me to achieve). Thats without any speculative information about already being well above the required gradient because the failure happened when I'd already been climbing all engines and arguements about take off climb increment because I got airborne earlier than I would have if one had failed at V1. Chaps you have turned what I hoped would be a useful technical discussion into a bit of a personal attack and accusations have been made by Clrdrv and others that I'm doing something out of line with the AFM. I'm absolutely not.

400 feet is a company SOP at Flight Safety and talking to the guy there I don't particularly disagree with their logic (especially for the Challenger) - as he said to me its roughly consistent with V2+20 anyway so why am I worried?
I do, however, think this information is important for aircraft with higher power to weight ratios and wings that are more efficient at lower speeds - the XLS, Soverign, probably the Hawker etc.

If you look at the start of this thread I was discussing pilots leaving flap retraction to some other arbitrary height (400 feet, 1000 feet, 1500 feet, whatever) when a flap retraction height does not exist anywhere in the regulations for all engines operation. The FAR's and the JAR's both refer to the case where the critical powerplant has failed at V1, not the all engines operating case.

I object very strongly to being called a test pilot and a bar practice pilot. Very few on PPrune use their proper names when posting and the anonymity means you can say what you like, you can make up regulations, you can do whatever you want really but I post under my own name because I carefully work through the discussion and stick by what I say. If I'm wrong, post the regulation and that way we all learn (me especially).

If anyone wants to have a proper discussion about this maybe you could give me a call instead - I'm not really interested in a slagging match. I just wanted to really get to the bottom of all this.

Tom +447850 915510

[tommoutrie]

Mutt you raise a point about turn radii as described in book 2 of doc 8168. I don't deal with this problem by just flying all departures in the same configuration. If the turn radii require specific speeds that mean the use of flap I brief the use of flap for that reason. That's pretty rare for me as most of my flying now is in Africa but there are plenty where I do this in Europe.

Your comment about acceleration altitudes higher that 1500 feet interests me. Whats your AA out of Geneva? I'm quite happy to go offline with the chat and do it by email if you like but I'm interested in your concept of selecting an AA higher than 1500 feet.

By the way, what do you fly and whats your actual profile for a noise abatement departure and a non noise departure?

Cheers

Tom

By the way, can you post me a reference to a flap retraction height in a Boeing manual. Its not in the 757 manual because I've checked and I was on the phone to a guy doing a 737 rating earlier who has checked with his instructors and its not in the 737 manual either. As we have already established earlier in the thread, its not in the Gulfstream manual, its not in the Bombardier manual and I haven't seen a post with an AFM reference which gives 400 feet as a flap retraction criteria yet. I'm not saying that one doesn't exist, I'm simply saying I haven't seen one and nobody, for all their comments, has posted one yet.

[I.R.PIRATE]

Dude....

I can't seem to quote off the iPad for some or other reason, so I highlighted the poignant bit.

I would like to ask you one question that will settle this for me.

Can you accurately predict when you are going to have an engine failure?

[mutt]

but I'm interested in your concept of selecting an AA higher than 1500 feet. Not my concept, its officially called extended second segment :) I'm far away from home, so no specific data for Geneva with me.

170 KIAS, 1500 feet FLCH (Power Change) 3000 feet accelerate to 200 KIAS, Flaps up. G4.

Have the guy in Montreal give you a "No Technical Objection" letter for flying that profile? :)

Mutt

[tommoutrie]

ir pirate. No I can't. Whats your point?

[tommoutrie]

Mutt. What on earth are higher than standard acceleration altitudes?

Whats the certification process for that? Is that in the FAR's - never seen it. Is it in the AFM?

[tommoutrie]

amusing really, I'm still the only one that actually posted a profile.

What profile for both noise abatement and a normal departure and on what aircraft do any of you fly?

[mutt]

As I told you, our standard acceleration height is 800 feet, not the FAR minimum of 400 feet, so anything higher than 800 feet is non standard for us. As i said, extended second segment as per the AFM.

In fact if you look at the ACJ, you will find Min Acceleration Height and Max Acceleration Height (based on the thrust limit), so this is more common than you think.

Nose abatement for G4, 170 KIAS, 1500 feet FLCH (Power Change) 3000 feet accelerate to 200 KIAS, Flaps up.

Normal Profile, target speed 200 kts, 1000 feet Flaps Up, FLCH (Power Change)

Mutt

[Cough]

Tom,

Ref the Boeings, the two engine profile is something along the lines of (non noise abatement)

R/w to Aa- v2 to v2+20 with full thrust or derate.
At Aa, select climb thrust and accelerate.
Final flap up at around v2 + 60 ish knots, can be more or can be less, depends on weight. Min clean speed v2 + 80 ish, depends on model.

Hence the initial climb speed will never be lower than flap up speed. If I retracted flaps below Aa, I'd loose my job....

Background - 10+ years 737 cl, currently Airbus...

[I.R.PIRATE]

My point is you seem to misunderstand the different take off segments.

Second segment being the key here.

[Richard Westnot]

What an interesting thread. I am still not sure who is buying who a beer yet ;)

[mutt]

By the way, can you post me a reference to a flap retraction height in a Boeing manual. Its not in the 757 manual because I've checked and I was on the phone to a guy doing a 737 rating earlier who has checked with his instructors and its not in the 737 manual either. Look at the bottom of a standard Boeing Takeoff Chart :)

Mutt

[provo]

Tom, I seem to recall someone mentioning that that Falcon 2000 AFM mentions no flap retraction until 400ft. Don't fly one so can't be sure

[B200Drvr]

Tom

Cut and paste from the G550 MANUAL/ AFM

The obstacle clearance procedure is to climb with landing gear retracted,
flaps in takeoff position at a speed of V2 to at least 1500 feet above the
takeoff surface. Use of the obstacle clearance data in this section will
ensure that obstacles will be cleared by a minimum of 35 feet for dry
runway takeoffs. For wet runway takeoffs, 20 feet must be added to heights
read from the charts to assure 35 feet minimum clearance.


A Gross Level-off Height correction grid has been added to these charts
to account for the reduction in climb performance that results during the
climb from the airport pressure altitude to the recommended level-off
height. This Gross Level-off Height grid corrects the base climb gradient
capability at a height of 400 feet above the airport to the average climb
gradient available between the base height of 400 feet and the
recommended level-off height. Before the available climb gradient can
be determined, it is first necessary to determine the recommended leveloff
altitude from the Distant Obstacle Clearance chart. As indicated in
the title, these charts present available net climb gradient performance.
Per CFR 25.115 (Takeoff flight path) for two-engine airplanes, the gross
climb gradient is 0.8% greater than the net climb gradient.


In addition to criteria governing accelerate-go distance and the items
discussed above, the following procedures and assumptions also apply:
1. No configuration change, except gear retraction, is assumed to
be made prior to reaching a gross airplane height of 1500 feet
above the takeoff surface.
2. Gear retraction shall be initiated immediately after lift-off and
positive climb is indicated.
3. The airplane shall attain speed of V2 prior to reaching a height
of 35 feet above the takeoff surface and continue at a speed as
close as practical to, but not less than V2, until reaching at least
1500 feet above the takeoff surface.
4. Net takeoff flight path data shall be determined in such a
manner that they represent the airplane’s actual takeoff flight
path diminished by a gradient of climb equal to 0.8%.
5. Bank angle not to exceed 5°.

[B200Drvr]

Tom.

That does go to prove one thing about your theory!!

G550 obstacle clearance is based on an extended 2nd segment climb
(Flaps 10° or 20°, gear up) to at least 1500 feet AGL. Because of this
and the fact that the FAR and JAR Final Segment (flaps up) climb
requirement is never more limiting than the Second Segment climb
requirement, Final Segment climb speeds and climb gradients are not
presented in the AFM.

[Roger Greendeck]

Tom, I wholeheartedly agree with your logic and reasoning. You are not mad after all! Flap retraction should be speed related andspeed related only.

The starting point for all this must be obstacle clearance. The basic requirement is to ensure you have it. OEM’s provide information in their AFM’s in the forms of procedures and performancei nformation in order for you to be able to calculate it in advance. After you start the takeoff, however, your actual performance is what matters. There have been a few comments about becoming a test pilot, not so. The departurehas the gradients required and hence you know the rate of climb required for your speed. If you’re making that or better then you are meeting the climb requirements regardless of whether your aircraft has a graph to tell you in advance. If you are qualified on a type you know if you are flying an aircraft with loads of excess performance on one that is very limited. I have flown aircraft have sufficient excess performance available that an early flap retraction is possible and considered normal. I have also flown aircraft that are on the bones of their arse for climb performance and no-one in their right mind would start accelerating early.

In the case mentioned early on of setting 15 degrees nose upand letting the aircraft accelerate to V2+50 I can’t see any sound reason forthis choice. I can see why a pilot maywish to maintain V2+10 (or whatever your aircraft uses) until acceleration altitude but if you are limiting yourself to a deck angle and accelerating in the climb to well above that speed then you have the performance to retract theflaps. If you have thrust to be able to accelerate whilst maintaining your required climb gradient and you reach min flap retraction speeds then there is no reason not to retract. In fact you will be in a better placed if an engine fails at that point. If, however, you are in a more performance limited aircraft and you need a level acceleration segment then you can’t just throw that in whenever you feel like it.

[I.R.PIRATE]

What is your flight director telling you to fly? Speed or pitch? And when does this change?

Secondly assume a hot and heavy day - you rotate, hit V2+20 and select flaps up by 150ft. Before the flaps are gone, you lose a donkey. Where do you now stand in terms of guaranteed obstacle clearance? And what would be your actions now?

[DA50driver]

Somebody beat me to it and posted the AFM for the G550.

I always question why we do things as well as you seem to do. So many things we do are left over from long ago with entirely different machinery.

If everything is normal I retract the gear and then do flaps at 400' as long as I have reached the required speed by then. If I am heavy and its hot I might not be there by 400'. (Our FD goes to a pitch that gives you V2 on one engine). Once flaps are raised the speed schedule changes and we can select a vertical mode. (FLCH, vnav or VS). I hate FLCH, so I usually go VS and enjoy hand flying the plane while monitoring speed.

If everything goes to hell we hold v2+ to 1500' or msa. Then level off and accelerate.

By leaving the flaps to 400' I am covered in case one quits. Other than that I like it and it works. Since I am the PIC I do it my way.

The other more interesting thing I have always argued is that if you need the performance why not start the takeoff with flaps 20 to get the shorter roll, then if an engine quits bring the flaps to ten and get rid of the drag. I have not gotten any traction with that at all.

Good luck with your arguments, you make some good points. Always ask "why".

[Roger Greendeck]

The flight director tells you what you set it up for. In my last aircraft I had performance charts for clean and take off flap so the answer in that case is if the engine stops I had a known speed to slow to and could plan my performance in advance.

Whilst I would have done my planning based on the engine stopping at V1 and climbing at V2 to acceleration altitude if I was at V2+20 with the flaps up or even retracting when the engine stopped I was already above the profile for a V1 fail and my climb angle was better at V2 clean.

[tommoutrie]

Hello cough

Which AA are you talking about? Lots of companies impose one (Ryanair for instance impose an MFRA of 1000 feet) and at Ryanair if you raise the flap before you have gone through that you'll get into trouble. But that's not a directive from Boeing. I have found a reference in the Boeing 737 classic training notes that suggests the minimum height for flap retraction is 400 feet but its the only manufacturers recommendations I can find.

If there are company imposed limits that's absolutely fine and you can't breech them but it's still okay to understand why they are there.

[tommoutrie]

B200, just to re-iterate. Putting your post in bold is the equivalent of shouting and it really doesn't help get your point across.

What you quote from the Gulfstream manual is all in accordance with part 25.115, the conditions of which are (amongst others) are for a failure of the most critical powerplant at V1.

In the extraordinary event that the powerplant doesn't fail a number of interesting things happen. One is that you rotate earlier in terms of distance along the take off roll. Another is that you overcome the initial drag of flap and gear more easily. If you get rid of the gear promptly and continue to accelerate to V2 you can then pitch for your initial climb and achieve a much better gradient than if you lose an engine at V1. Crucially you can also keep accelerating. Once you achieve the point (in terms of speed) where you can retract the flap you will further increase your rate of climb. Your gradient will depend on what speed you choose to accelerate to. However, if you choose to argue that raising the flap will somehow degrade either your rate of climb or gradient, why would you raise the flap at all? Why raise it at 1500 feet? Why not continue to climb in the flapped condition and benefit from the increased performance?

You only degrade the gradient if your forward speed becomes high - remember we are still all engines operating here so the gradient will only become an issue at the point where your forward speed is so high that you degrade the climb such that it impinges on the original required gradient.

Hopefully we are all on the same page so far - now what happens if you lose an engine?

If we lose an engine from V1 up to V2+20 I think we are all on the same page.
If I have started to retract the flaps - ie the flaps have just started to travel at the point where the engine fails - I am STILL in an improving situation and here is the reason. All the time the flaps are travelling, the drag is decreasing. Thats why we retract the flaps at 1500 feet as explained above. All thats happened is that I have used the extra energy of having two engines operating to retract the flaps and attain my final segment configuration at an earlier stage. The climb rate clean at my flap retract speed has to be as good or better than in the flapped condition at V2 because thats why I retract the flap at 1500 feet. All the time the flaps are travelling from the take off position to the up position the trend is towards this better configuration.

Next case. Lets say I'm now clean and climbing at 4 or 500 feet, speed is now above V2+20, more like V2+40 or 50 and increasing. I'm now quite a long way above the required gradient because both engines have been operating but I agree completely that I have no way of proving how much and I haven't factored that into my calculations because its an unknown. Now the engine fails. I need to reduce speed to V2+20 which will give me back the known gradient that I need. I'm in the final segment configuration and climbing with max thrust because I still have time available (I've got up to 5 minutes). After that I will reduce thrust to max continuous for the one engine I have left and now that things have settled down I'll deal with the problem.

At all times, I'm above the gradient. If you (or anyone else) believes that the climb is degraded by raising the flap and flying clean what is your justification for doing it at 1500 feet? Because if its "they told me to" you haven't thought through the problem. When we learn about this stuff we focus heavily on the most critical condition - the whole thrust of this from me is that I dont think we work through this correctly and at every stage. I think we should. I think the manufacturers do and thats why, for a substantial number of aeroplanes, the manuals are written the way they are.

There are advantages to doing what the AFM says. In the event of a failure of a powerplant higher up the initial climb, you are likely to be in a better configuration for the climb and have an aeroplane which is substantially easier to fly. Because you are faster the fin is more effective so the initial rudder correction will need to be less - if you don't recognise it immediately (and the majority of engine failures are not like the events in the sim - there's a high level of shock, stress, vibration, possibly noise, probably horrible smells etc) I believe that what I'm talking about gives you a better chance to deal with it.

I don't fly noise abatement departures at all in Africa because off the very high chance of birdstrike. I don't want to hit birds when I am 20 degrees nose high with all my focus on the artificial horizon, the ASI, and generally scanning in the cockpit. I want the aircraft in a sensible climbing attitude, accelerating sensibly, and I want to see the monitor birds, the herons, and the clouds of swifts etc so that I stand a chance of avoiding them. At 200 kts and climbing the way I do I have seen and been able to miss large birds on a number of occasions and when you are climbing out of Kinshasa and all thats beneath you is jungle and the Congo river you think carefully about how you are going to climb the plane.

I'm not really enjoying the thread any more because I feel that some of you are so entrenched in one way of thinking that you don't even read the posts properly and simply sign on to have a gang mentality rant. Thats not why I started this - it was actually to discuss why some operators go blasting through the flap up speed and only retract flaps because they achieve a certain height and I don't understand that mentality.

I wanted to provoke a discussion and perhaps uncover something interesting and I have other things I'd like to discuss with regard to noise abatement (my first job was as an Acoustic Engineer for a company called Bruel and Kjaer) and I think with some cohesive discussion and effort we can present sensible noise solutions for business jets which are much easier for us to fly.

but I'll only get shot down so whats the point!

[tommoutrie]

..I've been gang ranted..

[Capt Fathom]

There has been 194 posts so far!

Of which 84 are from tommoutrie, the thread originator!

I think you could safely say he has hijacked his own thread! :ugh:

[B200Drvr]

Tom,
Now you have lost me, firstly typing in caps is considered shouting, bold is distinguishing between what is quoted out the 550 manual and what is my own opinion, everybody knows that!!

Secondly,There are advantages to doing what the AFM says. with that statement you went from being sensible to being a cowboy, You yourself said the AFM is the bible, I fly by the AFM, that is what is quoted there. Read post 187 you will see that I have no quibble about the second segment climb issue and I understand that the performance of final segment is always better than second segment. However, you have missed on vital piece of information in your quest to conquer all, the performance is calculated from 400 ft AAL, as stated in the G550 AFM, thats they way I read it.

[cldrvr]

So now we have a handful of posters here who don't understand the different segments of climb.

This thread is proven to be highly entertaining, though slightly worrying if any of you guys are real pilots and not just 16 year old flightsim drivers....

[B200Drvr]

I don't fly noise abatement departures at all in Africa because off the very high chance of birdstrike. I don't want to hit birds when I am 20 degrees nose high with all my focus on the artificial horizon, the ASI, and generally scanning in the cockpit. I want the aircraft in a sensible climbing attitude, accelerating sensibly, and I want to see the monitor birds, the herons, and the clouds of swifts etc so that I stand a chance of avoiding them. At 200 kts and climbing the way I do I have seen and been able to miss large birds on a number of occasions and when you are climbing out of Kinshasa and all thats beneath you is jungle and the Congo river you think carefully about how you are going to climb the plane.

I am sorry, I don't buy that either, although my profile says IE and HK, I am actually from Africa and you have more chance of being shot at in the Congo than hitting a bird, maybe you should re-evaluate your departure profile!!
I am just saying!!

[B200Drvr]

Cldrvr, If that is aimed at me, please read my post again properly, you will see it is related to a statement that Tom made regarding basically converting 2nd segment into final segment, a statement that I agree with because that is basically what He is doing, furthermore, the bold print is quoted out of the 550 manual.

[His dudeness]

This thread is proven to be highly entertaining, though slightly worrying if any of you guys are real pilots and not just 16 year old flightsim drivers....

Now you got me... :bored:

[cldrvr]

What is your flight director telling you to fly? Speed or pitch? And when
does this change?

Secondly assume a hot and heavy day - you rotate, hit
V2+20 and select flaps up by 150ft. Before the flaps are gone, you lose a
donkey. Where do you now stand in terms of guaranteed obstacle clearance? And
what would be your actions now?


Tom just doesn't get it, he would rather stick to his own SOP's and ignore the AFM/regs/OM's despite what several of us have told him.

[tommoutrie]

Pitch. It changes when I make a mode selection.

If you choose to take the flaps up at 400 feet at V2+20 the aircraft is still compliant. It has to comply with the climb gradient and I think its clear from all the posts on here that everyone agrees that if you take the flap up at 400 feet it will still comply with the climb. Thats what most people think the normal take off is - flaps up at 400 feet with a speed check of V2+20 (for my plane, different on others). Everyone seems happy that its compliant from 400 feet - well lets check that.. is everyone happy? Or is anyone of the opinion that once clean, if you have an engine failure you should reduce speed to V2 and reselect the take off flap? I've had that one sent privately too..

The flaps neither know nor care how high the aircraft is. If the gradient clean from 400 feet is good enough it will be good enough from wherever you actually select the flaps up because it will be the same gradient because the speed is correct.

I'm really open to the flaws in this but its exactly whats in the Bombardier manual and various Cessna manuals and the Embraer manual. The problem is that they don't explicitly deal with the engine failure after flap retraction in the climb case. They only deal in detail with the engine failure at V1 case.

I've got no issue with using 400 feet as a platform below which there should not be a flap retraction but I think its important that pilots retract the flap for the correct reason. I also think that its important that people understand whats happening. Close inspection of the 737 manual discusses reduced acceleration altitudes in the case of hot and high performance precisely because the gradient and climbs achieved once clean are better than the flapped gradients and climbs.

I'll be completely honest here. I've received a couple of fairly unpleasant emails regarding my professionalism and its not the sort of thing I enjoy reading so its time for me to call a halt to this. I'm sorry I brought it up!

[His dudeness]

I'll be completely honest here. I've received a couple of fairly unpleasant emails regarding my professionalism

No need to be sorry, the guy(s) sending you mails like that should be ashamed.

I personally like someone who still thinks about things 'later' in its career way better than the guys who don´t. As long as one can discuss without resorting to personal abuse its all fine to me.
The thread served at least to make me rethink procedures etc., although I think I operated in line with the manual/training.... Thanks for that, Tom! :D

[500 above]

Where I think the confusion lies is that there are various certification platforms for an acceleration altitude (ICAO, for instance, use between 400' and 1500') for the acceleration platform in the event of an engine failure but this still is not the criteria for flap retraction - its only about speed!

Not quite true, Tom. The JAR's and FAR's also state that the minimum flap retraction height is 400'. My present types (JAR/FAR 25 type) AFM also states this height, although its a rocket and speed is usually way above V2+10 way before this height.

This is another thread on the subject here:

http://www.pprune.org/tech-log/319858-mfra-acceleration-altitude.html

[tommoutrie]

hello 500 above

As discussed before, the conditions for both the FAR25 and JAR 25 are for the failure of the critical operating engine at V1. 400 feet is a certification limit under these conditions. Earlier in this thread I've explained why I believe this does not prohibit the retraction of the flap in the case where all engines are operating. That is also why the AFM's do not refer to 400 feet in relation to flap retraction on an all engines operating take off.

I'm definitely not saying that no AFM exists which has this condition written in. I am, however, saying that the case of an engine failure after the flap retraction speed or even further up the climb, is not explicitly defined. Perhaps you could read a couple of the earlier posts regarding this to see if they make sense - if they don't, then post. You may be absolutely correct and I may have completely missed something.

cheers

[BizJetJock]

Tom, you're missing a couple of fairly fundamental points.

First, the AFM's on all these aircraft are pretty vague on operating detail, precisely because they expect operators to write procedures based on local conditions and requirements. So it doesn't prohibit retracting the flaps as soon as you can, and it also doesn't prohibit leaving them extended.

Second, other rules apply. I know you fly for an EU-OPS operator, so every takeoff where you don't fly a NADP is illegal. Also every takeoff where you don't follow your Part B is illegal. So if your Part B doesn't contain a NADP (it doesn't have to be exactly one of the ICAO profiles) that makes your entire fleet non-compliant. The fact that CAA audits haven't picked this up is not a defence in court, it is the operator's responsibility. And if you as the captain choose to operate illegally, good luck.

With those points in mind, then the profile used by several Challenger operators is quite sensible. The ICAO brief is V2+20 or as limited by body angle to 800 feet then reduce power and either start accelerating to clean up or leave flaps down to 3000 then accelerate. V2+20 for a Challenger varies between 150 and 180 depending on the conditions, but the body angle particularly at light weights gets excessive, so by saying 190 it keeps the pitch below 20 degrees and the speed below Vlo. Note that you are flying a target speed; if you just hold a pitch you can easily at light weights exceed the gear limit speed before the doors have closed. Leaving the flaps down helps!!It gives you a lower pitch angle for any given speed and the drag also helps keep the performance reasonable. They then use 1500 feet as an acceleration height as being both a reasonable compromise between the 800' and 3000'options while giving a common procedure with the engine failure case. In the event of an engine failure below 1500' all you have to do is control the yaw (easier with the higher speed) and let the speed drift back to V2+10 safe in the knowledge that you are above the obstacle clearance profile. And also, again, note that 1500' is the acceleration height; in practice on a normal departure you are already well above the minimumflap retraction speed in the AFM, so can do so immediately.

Now, against that, can you actually tell me what is the advantage of retracting the flaps asap after takeoff?

[Cough]

Hello cough

Which AA are you talking about? Lots of companies impose one (Ryanair for instance impose an MFRA of 1000 feet) and at Ryanair if you raise the flap before you have gone through that you'll get into trouble. But that's not a directive from Boeing. I have found a reference in the Boeing 737 classic training notes that suggests the minimum height for flap retraction is 400 feet but its the only manufacturers recommendations I can find.

If there are company imposed limits that's absolutely fine and you can't breech them but it's still okay to understand why they are there.

We call it AA, min height for change from takeoff thrust to climb thrust. Doesn't matter what the term is, its the meaning...

Another 400' reference that I have found is contained in the 737 QRH. It contains the normal takeoff profile which shows earliest points for things to happen. 400' is the earliest point you start anything...

Takeoff profiles - From what I've read, you maintain max thrust till after flap retraction, we reduce thrust before. To accelerate to 250 kt (initial climb speed) takes a few miles (at 1000fpm ish). So say I were to start that after take off once the gear is up, we would be flying very low for a few miles and trust me, if the company didn't get me the journalists would (for low flying...)(rightly...)

Lastly, You've said that clean at V2+20 you get a better climb rate than with flaps out at V2 and you have the graph to prove it. I accept that, but a quick question is, do you have a climb graph for takeoff flap and V2+20? Improved climb is a well researched area...

[tommoutrie]

Thats a good post biz, thanks.

Ok

First, the AFM's on all these aircraft are pretty vague on operating detail, precisely because they expect operators to write procedures based on local conditions and requirements. So it doesn't prohibit retracting the flaps as soon as you can, and it also doesn't prohibit leaving them extended.

That is absolutely correct.

then the profile used by several Challenger operators is quite sensible. The ICAO brief is V2+20 or as limited by body angle to 800 feet then reduce power and either start accelerating to clean up or leave flaps down to 3000 then accelerate. V2+20 for a Challenger varies between 150 and 180 depending on the conditions, but the body angle particularly at light weights gets excessive, so by saying 190 it keeps the pitch below 20 degrees and the speed below Vlo.

I agree with most of that but I don't agree that exceeding V2+20 flapped is of any benefit at all. If you are light and your V2 is 130, V2+20 is 150. If you fly a correct noise abatement profile you will reach 2000 feet at a point which is 2/3rds of a mile closer to the airport than you would if you did it at 190 ie at 2.5 miles rather than at almost 3.2 miles. The whole point of noise abatement is to reduce the noise footprint for close neighbours of the airfield whether it be NADP1 or 2 so I'm not sure the profile you've described fulfils the requirement. For some time I've tried to find a way to negotiate with the authorities from the standpoint of my former career as an acoustic engineer and argue that with the power to weight issues that small business jets have that an earlier power reduction to contain climb rate and limit body angle is far more sensible than trying to contain it by excess drag. It makes no sense to respect one part of the guidelines and ignore another and reducing power would make much more sense. This is why I suggested another thread for discussing noise abatement.


Note that you are flying a target speed; if you just hold a pitch you can easily at light weights exceed the gear limit speed before the doors have closed. Leaving the flaps down helps!!It gives you a lower pitch angle for any given speed and the drag also helps keep the performance reasonable. They then use 1500 feet as an acceleration height as being both a reasonable compromise between the 800' and 3000'options while giving a common procedure with the engine failure case.

Again, controlling the speed with extra drag on take off is contrary thinking in my opinion. Surely a power reduction is more sensible. Explicit in the regulations is that departure from published noise procedures is permissible for reasons of good airmanship and exceeding a limiting factor on the aircraft is surely one of those. But I think a group approach with regard to discussing this with the authorities would be a good idea.

In the event of an engine failure below 1500' all you have to do is control the yaw (easier with the higher speed) and let the speed drift back to V2+10 safe in the knowledge that you are above the obstacle clearance profile. And also, again, note that 1500' is the acceleration height; in practice on a normal departure you are already well above the minimumflap retraction speed in the AFM, so can do so immediately.


Slightly confused as to what you're saying here - I would argue that if you were climbing in excess of V2+20 and had raised the flap there would be no need to fly an acceleration segment (as previously discussed) and the fact that you have had to slow down from 190 (in this case thats V2+60) to V2+10 and then pitch for level acceleration to accelerate back up to V2+20 to raise the flap will degrade the net climb gradient far more than simply reducing speed to V2+20 and climbing at that. Actually there is still a level acceleration segment for both these because there's a further acceleration to 190 for the enroute climb but I think thats obvious to all.

Now, against that, can you actually tell me what is the advantage of retracting the flaps asap after takeoff?


Ok. Firstly I'm not sure that the profile you described is compliant (exceeding V2+20 by such a large amount) and if you are going to fly a non compliant noise departure you may as well make it as quiet as possible. I would suggest that cleaning up and climbing with reduced thrust (ie not climbing against drag) would be a more efficient way to do this but from a compliance point of view the best thing to do is fly the NADP as laid out. As stated before, I don't think its an easy profile for us to fly and we should negotiate with the authorities to get a more sensible profile for business jets but until that time I think we have to do what we have to do.

Also, this isn't a discussion about Challengers. Soverigns, XLS's, even aircraft like the Phenom 300 and the CJ3 really struggle to implement these rules correctly - most just don't bother. So why don't we try to solve the problem?

Also, climbing against drag wastes fuel. Not much fuel I'll give you that but I don't understand the philosophy of wasting any at all.

[Roger Greendeck]

Humour me specifics, what regulations impose a restriction on flap retraction. Company procedures don't count as this discussion is abut the 'why'.

[mutt]

Roger, FAR 25.111, I'm sure that CASA have a similar regulation. This however deals with an engine failure at VEF. Now if you can get your aircraft manufacturer to guarantee that you will clear all obstacles in the takeoff flight path if you immediately retract the flaps at V2+X, then this conversation is over. However, none of us have certified data stating this, and therein lies the problem, we aren't looking at this from a purely aerodynamic point of view, we are looking at being able to prove regulation compliance with our operating authorities, or in the event we ever end up in a court room.

Tom, the fact that you have never heard of extended second segment shows me that you have never dealt with the concept of increasing the acceleration height to clear obstacles, we can have the second segment climb continue for almost 10 minutes, with this in mind, its much easier to only have a procedure based on an altitude rather than a speed.

Unfortunately manufacturers usually only certify the data that is required for the AFM, primarily due to time and cost constraints, this leads to things being treated in isolation, they will look at the requirements for FAR 25.111, they wont certify this procedure for all engines. Your aerodynamic argument is good for small aircraft, it doesn't work for larger aircraft, as someone else has posted, it takes them too long to accelerate to the retraction speed.

But the fact remains that one day you might find yourself having to justify your actions, and unfortunately the only thing that you have to help you is the AFM.

It's a shame that some people have taken to emailing you, if we cant discuss these issues, how are we ever expected to learn from our mistakes?

Mutt

[tommoutrie]

Hello Mutt

I know exactly what an extended segment climb is - its impractical on the 601 as I explained before as I only have 5 mins at max thrust on one engine.

I think you are correct - the answer I need to get from Bombardier, and more importantly, find a generic answer, is if the flap retraction occurs at V2+x having been all engines operating to that point, is obstacle clearance guaranteed. Thats a useful comment and you're right. My belief is that given everyone on here agrees that its ok to take the flaps up at 400 feet that the answer is yes. Otherwise, why would it be ok to take flaps up at 400 feet? The gradient you get clean at V2+x from 400 feet has to compare favourably to the one you would get at V2 flapped otherwise you couldn't do it.

The gradient will be the same if you are V2+20 clean whether you are at 400 feet or 200 feet or 600 feet so how could it not be ok?

You would always have to leave the flaps in the take off configuration until you got to 1500 feet. And that is clearly not the case - I hope we can all agree on that.

I completely get that hardly anyone on here agrees with me but thats irrelevent - lets get proper answers from manufacturers and perhaps the now muddied waters will clear. I will let you chaps know what answers I get - hey, if I'm wrong, I owe a lot of beer! If I'm right, we all get a bit of info out of this.

[mutt]

I think that you will make your life a lot easier if you just accept that you are talking about the CL601 ONLY :)

My one interaction with Bombardier was related to the CRJ, due to a lack of computerised software, they had a hard time validating ANY takeoff weights, so I would be extremely surprised if they can give you a proper answer related to all engine performance.

Good Luck and make mine a Guinness :)

Mutt

[Roger Greendeck]

FAR 25.1 Applicability 'This part prescribes airworthiness standards for the issue of type certificates, and changes to those certificates, for transport category airplanes.'

In essence FAR 25 does not restrict us as pilots. It is for certification purposes and the configuration changes are to stop manufacturers from using a complex and difficult configuration change in order to certify the aircraft.

Not sure about other countries but in Australia the reg that applies to us is CAO 20.7.1B which covers planning and executing a take off. In our case we need to be able to ensure 35' obstacle clearance on departure and 50' in a turning departure.

It states: 'An aeroplane may be accelerated in level flight from V2 speed to final take-off climb speed at a height above the take-off surface that is the greater of:
(a) 400 feet; or
(b) the height necessary to achieve obstacle clearance in accordance with paragraphs 12.1 and 12.2.'

If you don't need to fly a level segment and still meet the obstacle clearance your good so far. It goes on to say:

14 AEROPLANE CONFIGURATION AND PROCEDURES
14.1 Paragraph 14.1A applies if:

(a) the manufacturer of, or the holder of the type certificate for, an aeroplane

has published advice, recommendations or guidance (the information)about the performance of the aeroplane in an emergency, unusual
operating conditions or an abnormal configuration; and
(b) the aeroplane is in the emergency, conditions or configuration.

14.1A The pilot in command of the aeroplane must take the information into account
when planning the take-off or landing of the aeroplane.

14.1B In subparagraph 14.1 (a), type certificate includes foreign type certificate

within the meaning of paragraph 21.041 (1) of the Civil Aviation Safety Regulations 1998.
14.2 Procedures to be followed consistent with this Order, including procedures
anticipating engine failure at any time between the commencement of take-off
and completion of landing, must be specified in the Operator’s Operation
Manual. The procedures so specified must be such that they can be consistently
executed in service by flight crews of average skill and they must also be such
that the take-off flight path with all engines operating is above the one-engine
inoperative take-off flight path.

How do I interpret all this? Unless the manufacturer has a specific procedure my company needs to have one and that procedure could allow the retraction of flap as soon as you reach flap retraction speed as long as you meet the obstacle clearance OEI and all engines and does not require a level acceleration below 400'.

[BizJetJock]

I think the 400' for flap retraction comes from people using the same logic about keeping the configuration the same, but not updating it after 1970 when aircraft started having the performance to get higher before having to accelerate!

Tom, my comment about the flaps helping the initial climb was from a handling perspective, not a performance one. All your calculations may well be correct, but that doesn't alter the current requirement, and climbing at 190 (or other suitable speed for different types) is compliant. There is an entire thread over on techlog about whether using reduced thrust for a NADP actually increases noise levels, but it is entirely academic.

Effectively at the moment, to use a car analogy, you are saying that because my car is more efficient at 50mph in 5th gear than it is at 30mph in 3rd I should ignore the 30mph speed limit. Unfortunately, the fact that your reasoning may be correct does not make the speed limit go away!

Therefore I will continue to follow my company's procedure which is compliant with the rules.

Happy flying.

[tommoutrie]

Thats very sensible biz. I think the NADP is flawed both from an aircraft handling perspective and from a noise perspective (as I mentioned, noise and vibration is my previous career and I worked for the company that made buckets of cash out of selling noise monitoring stations to airports amongst other things Airport environment management - Brüel & Kjær (http://www.bksv.com/Products/EnvironmentManagementSolutions/AirportEnvironmentManagement.aspx)). There's nothing unsafe in either method (actually I think strict adherence to the letter of both NADP1 and 2 has some safety implications for aircraft like ours). I hope you agree that the subject is also worth discussion at some point and not only on here - the rulemakers need to see the arguments against the noise profiles they suggest. The issue with the NAP's is that unless you force operators to remain at full chat you have no way to prove repeat-ability in your noise samples. The maths is just too complicated if you let people do the sensible thing and climb at a high rate in a clean configuration with the power reduced because who knows what noise you make when the throttles are in any position other than max take off. They take the simple option and say "max thrust, known noise source, make the aeroplane climb at the steepest gradient we can" because anything else can't be proved.

anyway, thats another thread..

[1Bingo]

WOW. It all sounds amazingly academically anal. But then, JAA certification is kinda like that.

Bingo

[tommoutrie]

it aint actually that complicated. Its simple. You can retract the flaps once the speed is correct.

If you need a level segment to achieve that speed the most common one to use is 1500 feet but you can use anything between 400 feet and the end of your single engine max thrust limit.

When you are all engines operating you can take the flaps up before 400 feet if you want because you don't need a level segment.

Mr Greendeck, thanks for that bit of legislation. I think I need to hunt around a bit more and find that written down in the northern hemisphere now! I've sent a written request to Bombardier and I'm probably going to send it to Cessna tomorrow to see if I can get some manufacturer responses. I won't bother with Hawker, they're all a bit busy..

[cldrvr]

When you are all engines operating you can take the flaps up before 400 feet if
you want because you don't need a level segment.

No, you can't. But that is OK, about 10 of us here have been saying that for the last 10 pages and you, Tom seem to be the only one who still does not get it.

[tommoutrie]

can you take the flaps up at 400 feet then? Is that ok?

[cldrvr]

Flaps up at 400 is perfectly acceptable unless you need an extended second segment. As to the rest, I actually mostly agree with you.

[tommoutrie]

Right. Flaps up at 400 feet.

Whats your plan for climbing away from an engine failure at 400 feet (I'll save you the detail of "you've just selected flaps up and you hit a bird")

Lets just assume that you made the miracle of 400 feet, you have achieved V2+20, and you've taken the flaps up.

Whats your plan now?

[tommoutrie]

hint.. If you answer a) I climb away clean I will refer you to your own post about having no data which you do actually but you've not noticed it
If you answer b) I take put the flaps back down and slow down and climb at V2 to V2+10....

actually.. maybe just wait for the answer...

[tommoutrie]

And lets examine that a bit further. Why would you need an extended 2nd segment climb? which airfield? I think I posted regarding Geneva didn't I? is that one you will schedule an extended 2nd segment climb for? Or are you relying on a performance calculator on a laptop to give you the answer? Does the use of an extended 2nd segment climb improve or degrade your overall net take off flight path?

anyone?

[tommoutrie]

all correct and mentioned earlier but mutt and cldrvr etc were busy shooting down such logic earlier in the thread because you can't prove it - there's no tables. However, final segment climb tables exist for my aircraft at least so you can prove what the climb rates clean are and thats with the power reduced to max continuous single engine - in the case of retracting flap at V2+20 (or indeed some arbitrary height should your operations require it) you would still be at max thrust so would exceed that figure.

All the other benefit - lifted off earlier, climbed better, probably going quite a bit faster, easier to fly clean than dirty - all thats a bit extra in the bank!

Mind you, still haven't actually heard back from CLDRVR with his plan from 400 feet so maybe we've missed something and are actually doomed..

[His dudeness]

Well well well, at my airplane I might (per CL) retract at 400ft & V2 +10.

V2 s are between 103 and 122 for Flaps 7° and 99 to 115 at 15°.

So I´d retract flaps with say 132 knots or 109 as the lowest figure.

Venr. is 180 KIAS.

I´d have to accelerate beteen 48 and 71 knots to get back to 'know territory'.

Flaps can be carried up to 200 Kias (15°) and 250 (7°).

We prefer 7° over 15° for much better second segment climb gradients. FSI/Cessna teach 15° for less wear and tear on the tires.

I´m not so sure that I´d stay above the required profile with an engine failing just as the flaps hit their up stops. Definitively not if I´d accelerate. Can´t gain that much height over distance up to 400ft methinks. At least there is no way to determine that easily, which is a requirement for dumb pilots such as myself...

But then the answer to the question is easy. not in the book, thus can`t happen. Done.

[tommoutrie]

see..

not quite as simple as everyone thought..

[His dudeness]

No Tom, it ain´t.

http://www.pprune.org/biz-jets-ag-flying-ga-etc/500603-flap-retraction-5.html#post7528407

But you can´t sell me my own question as yours !

[mutt]

all correct and mentioned earlier but mutt and cldrvr etc were busy shooting down such logic earlier in the thread because you can't prove it - there's no tables. You have changed your tune, in the beginning you were stating that you wanted to retract flaps as soon as you had the speed regardless of the height, thats what i objected to !

Now you are accepting that you will climb to the calculated acceleration height before retracting the flaps.

So i guess that we did get you to change your mind.

Mutt

[zzuf]

Well, what an interesting thread!
As picked up by Roger Greendeck the flight techniques of FAR/JAR 25 have nothing to do with flying operation. They are the airworthiness certification rules to which manufacturers demonstrated compliance and obtained a type certificate.
Airworthiness certification flight testing establishes some limiting conditions (amongst a heap of other things) on which certain operational procedures are developed eg Vmcg, Vmc, Vs, Vso, Vdf etc.
As far a FAR 25 take-off is concerned, the manufacturer has demonstrated compliance with the Vef failure and produced some sort of WAT chart which shows if your weight is legal to go flying or not. This gives the minimum acceptable one engine inoperative performance which has been agreed to give you a high probability of not flying into the ground because of lack of performance in event of failure of the critical engine at Vef. It should never be confused with obstacle clearance - this requires a survey of all obstacles in the flight path and application of the aircraft performance data to ensure these obstacles are cleared by at least the statutory requirement.
I would be surprised if many of our bizjet operators have survey information for the airfields that they operate from. That there are so few accidents in this area is probably the result of very few critical engine failures and the high performance levels available rather than the type of pre-flight planning done by say airline performance departments.
It is not the responsibility of the airworthiness authority to rule on how a certificated aircraft is operated, other than compliance with the airworthiness limitations in the AFM. That is the responsibility of the operator and the operations section of the regulatory authority.
I have yet to see any operational requirement that stipulates that, on take off, an aircraft must fly a profile that in some way replicates the profile flown by the manufacture to demonstrate compliance with minimum climb gradient requirements. The tests have been done - if you look at your WAT chart before flight and are below the WAT limit you are compliant. If you wish to fly that profile that is fine, but that doesn't mean that you will necessarily be compliant with operational requirements.
Some have commented on the lack of material in the AFM for this sort of operation - this is not an issue for the AFM, it is operational and should be in an ops manual.
Some have no clue about scheduled performance, one even commented on 2nd segment after flap retract followed by an engine failure.
So, all engines operating, retract your flaps whenever it is appropriate, you are not required in any way to fly a profile which replicates that used to demonstrate FAR 25 minimum acceptable one engine inoperative climb gradients. In many cases obstacles make such a profile an impossibility
Whatever you do, make sure you have planned a combination of ground track and climb performance which will ensure all obstacles are cleared by at least the minimum requirements after an engine failure (or more than one engine failure if that is the requirement) at any stage of the flight. While you are at it, make sure all the ops rules are covered as well.

[cldrvr]

FAR/JAR 25 have nothing to do with flying operation.


Oh yes it does.



I have yet to see any operational requirement that stipulates that, on take
off, an aircraft must fly a profile that in some way replicates the profile
flown by the manufacture to demonstrate compliance with minimum climb gradient
requirements.


I sincerely hope you are not a commercial pilot. If you are, going by your profile location, stop flying forthwith and familiarise yourself with your Part 20.

retract your flaps whenever it is appropriate, you are not required in any way
to fly a profile which replicates that used to demonstrate FAR 25 minimum

Are you for real? Or are you just helping some others here troll the thread for laughs.

[cldrvr]

At least we got Tom to agree on the 400 ft after 11 pages....

Now let's get the remaining stragglers to see sense here....

[gaunty]

zzuf

I have yet to see any operational requirement that stipulates that, on take off, an aircraft must fly a profile that in some way replicates the profile flown by the manufacture to demonstrate compliance with minimum climb gradient requirements. The tests have been done - if you look at your WAT chart before flight and are below the WAT limit you are compliant. If you wish to fly that profile that is fine, but that doesn't mean that you will necessarily be compliant with operational requirements.

If it is limiting then you have to fly your profile.

You might want to have a look at CAO 20.7 specifically 20.7.1b

And why does Airservices ERSA publish TODA and STODA information.

And why does the STODA provide Take Off distances for specific gradients, at 1.6%, 1.9%, 2.2% and 3.3%, look familiar?, in addition to the actual TODA gradient at each runway end.

And why cant you operate into or out of an aistrip that does not have that information available.

And why would you not use RTOWs calculated by performance engineers (we like most people including Jepp and Universal use APG) for specific airport runways as a convenient legal way of calculating an accurate weight at a given density altitude to assure that you can meet said obstacle clearance, without having to beat your calculator to death and/or get it wrong on your WAT chart.

Or maybe I'm just missing your point altogether.:hmm:

[1Bingo]

Incessant. You guys (and gals) have taken anality to a whole new level.

I feel sorry for the kid reading this thread who may now wonder if there are alternatives to V-speeds and configuration dictated by the manufacturer in the POH.

Please do, carry on.

Bingo

[tommoutrie]

quick one for mutt - where, in all the posts I have made, have I accepted the 400 feet is the correct minimum platform for an all engines operating take off?

somewhere around post 220 I think clrdrvr said he thinks its ok to raise the flap at 400 feet.

I asked the question, what data does he then use for an engine failure at that point.

haven't heard anything back since then.

maybe he hit a hill..

[tommoutrie]

tell you what, Bingo, if you are absolutely certain that you're up to speed with it all, why don't you post the answer for Cldrvr.

Take off, 400 feet and V2+x, engine failure, where's your proof to the authorities that you can climb away?

(I know where it is.... its in the same place that proves you can retract the flaps at V2+x and that 400 feet is a call that was dream't up by pixies and elves to annoy the ogre..)

...ps.. its 500 feet in the UK. CAP 778 applies...

http://www.caa.co.uk/docs/33/CAP778.pdf

CAP 778
Policy and Guidance for the Design and
Operation of Departure Procedures in UK
Airspace

[mutt]

Looks like I read your post #224 incorrectly......

Mutt

[tommoutrie]

hey dudeness, have you gone from being able to retract your flaps at 400 feet to not being able to retract them to 1500 feet or are you now re-planning all your flights with the flaps at take off from the start of the ground roll to the end of the landing roll.

now we're getting somewhere.

I think we have flaps so that in the event of a double engine failure you can put them up and down really fast and the aircraft gets pushed along by the thrust from the dolphin like movement.

Is anyone certain enough to take my bet yet?

[tommoutrie]

haha, yep mutt you did..

hey, dont tell the others but I had a 30 min call from Bombardier today.

email coming on monday.

and guess what.....

that dogs home is gonna get some new kennels.....

[tommoutrie]

mutt, you never told me..

400 feet, v2+x, then the engine fails.

whats your plan?

where's your data?

(by the way, I think zzuf knows more than he's letting on)

[mutt]

His dudeness has given you figures where he has to accelerate between 48-71 kts, based on your assumption that you can clean up at V2+X regardless of height, when do you suggest he levels off to accelerate, while ensuring that he doesn't fly into a mountain?

Mutt

[mutt]

400 feet, v2+x, then the engine fails.
whats your plan?
where's your data?

Continue climb to minimum flap retraction altitude, accelerate, retract flaps on schedule, select MCT when required, climb.

Note that we are accelerating at an altitude where we know that we have cleared the takeoff obstacles, you on the other hand, are not!

Mutt

[tommoutrie]

Ok I see. You are also saying that you can't retract the flaps at 400 feet because you don't think there's any data for OEI climb apart from the v2 with take off flap gear retracted table.

Is that right?

[mutt]

Flap retraction will be initiated at the most critical level-off height
while the aircraft accelerates to V SE. Upon reaching V SE, continue climbing with flaps retracted at Maximum Continuous Thrust until all of the other obstacles are cleared.

Taken from G4 AFM, it clearly shows that if you can clear the obstacles with a 400 feet acceleration height, then go ahead, if not increase the acceleration height. Thats why we stick with a Flap Retraction height rather than a speed.

How do you calculate your obstacle clearance?

Mutt

[tommoutrie]

I use Flugprestansa to get the close in obstacles and use the SID gradient for the gradient.

From your own AFM

Flap retraction will be initiated at the most critical level-off height
while the aircraft accelerates to V SE. Upon reaching V SE, continue climbing with flaps retracted at Maximum Continuous Thrust until all of the other obstacles are cleared.

What your manual says is retract the flaps at the most critical level off height (once you are clear of close in obstacles you can retract the flaps - this is what your manual is saying). Once you have achieved Vse (regardless of height, I added that bit because the bloke that wrote the manual thought it was clear) you can retract the flaps because THERE ISNT A CRITICAL LEVEL OFF HEIGHT ANY MORE and continue climbing WITH THE FLAPS RETRACTED until all the other obstacles are cleared. You calculate the weight you can carry for the temperature you intend to take off at. You take off. When you have cleared the close in obstacles and acheived the flap retraction speed you can retract the flaps. Then you can keep climbing. Thats it. Not complicated. In your own manual.

The tough bit is getting hold of the obstacle information and making sure that database is correct - ie have notam'd cranes and tethered balloons and the like been accounted for. Generally, obstacles are under the SID gradient so you just don't care about them because you're going to be above them anyway.

From an FGP of EGTE

Obstacles included in calculation: (Height above runway end / Distance from brake release point)
Oa: 488 ft/6687 m Ob: 185 ft/3965 m Oc: 174 ft/3900 m Od: 112 ft/3320 m Oe: 124 ft/3495 m Of: 63 ft/2785 m
Og: 88 ft/3142 m Oh: 48 ft/2645 m Oi: 275 ft/5530 m Oj: 36 ft/2517 m Ok: 242 ft/5304 m Ol: 952 ft/17567 m

Broadly speaking they are sorted in gradient order although I have come across anomolies before. This could be because FGP seem to sort the order from the start of the take off roll - obviously we are interested in the gradient from the DER so theres a bit of maths to do to correct the order but in this case its pretty much correct and the first obstacle is the limiting one at 3.2%. So I can choose to WAT limit my aircraft to comply with 3.2% and take off and actually know that I will clear any obstacle by the required amount because I've already calculated that the climb increment gained by my actual take off point will give me the clearance required (TCI). I do this as a cross check of the FGP data which simply gives me a weight limit and a QNH correction. I asked FGP to provide their data in a datastring form before because I wanted to perform further analysis but apparently its propriety. Also I mentioned the gradient sorting anomaly and they chap said they hadn't noticed that before so maybe that will change in the future.

Thus I have a way to comply with an engine failure at any stage. Before V1, V1 and above up to V2, V2 up to V2+20, and V2+20 and beyond.


By the way, have you found the bit in your G4 manual that says "you cannot retract the flaps below 400 feet because you cannot and you just cannot and don't ask why, you just aren't allowed" yet?

didnt think so..

[mutt]

You appear to have forgotten about DISTANT OBSTACLES? If you look at the AFM you will find a close-in and distant obstacle chart.

The tough bit is getting hold of the obstacle information and making sure that database is correct - ie have notam'd cranes and tethered balloons and the like been accounted for. Generally, obstacles are under the SID gradient so you just don't care about them because you're going to be above them anyway. Nope, for us, this part is easy....... we use the actual data rather than the SID.

By the way, have you found the bit in your G4 manual that says "you cannot retract the flaps below 400 feet because you cannot and you just cannot and don't ask why, you just aren't allowed" yet? Which part of our previous statements that the AFM was based on FAR/JAR (etc) requirements didnt you understand?

Thus I have a way to comply with an engine failure at any stage. Before V1, V1 and above up to V2, V2 up to V2+20, and V2+20 and beyond.
OK, but Mr Gulfstream has this to say......

WARNING
TWO-ENGINE SID CLIMB CRITERIA CAN BE EMPLOYED AT THE
OPERATOR’S DISCRETION. IF TWO-ENGINE SID CLIMB CRITERIA IS
EMPLOYED TO DETERMINE SID-LIMITED TAKEOFF WEIGHT AND AN
ENGINE FAILURE OCCURS EARLY IN THE DEPARTURE CLIMB,
CONTINUATION OF THE SID CLIMB ON ONE ENGINE SHOULD NOT BE
ATTEMPTED. INSTEAD, THE PILOT SHOULD DECLARE AN
EMERGENCY AND EITHER LAND OR ENTER A HOLDING PATTERN TO
GAIN SUFFICIENT ALTITUDE TO CLEAR OBSTACLES AND HIGH
TERRAIN. TWO-ENGINE SID CLIMBS SHOULD ONLY BE USED IN VMC
CONDITIONS WHERE OBSTACLES CAN BE VISUALLY ACQUIRED AND
AVOIDED.

So are you basing your weights on single or dual engines? What about the part about two engine SID's should only be used in VMC?

Mutt

[tommoutrie]

Two engine data is where you rely on a high climb gradient (as per Sion or similar) where you can accept the 13 odd percent climb gradient all engines operating but if you have an engine failure you must be in VMC conditions.

All engine operating data give you the all engine climbs. Thats why they say you must be VMC.

You appear to be a pretty knowledgeable and probably quite senior pilot. Either you must, by now, be happy to take my bet or somewhere, sitting at the back of your mind, is the niggling doubt that all this makes sense and actually we have all been really badly taught.

bet?

go on, you know you want to... :hmm:

[tommoutrie]

Actually, the high performance SID out of sion is exactly this issue. You stand no hope of achieving it one engine inoperative (thats what 3 engined business jets are for) but you can accept the high performance gradient because you are all engines operating. But you can only accept it in VMC conditions because then, if you have a failure, you can climb visually.

[Doug Neidermeyer]

Darwin Awards comes to mind...

[tommoutrie]

no thats right - the CAA don't and I'm pretty sure you can't do this at Sion any more but its exactly why the two engine performance data exists for some aircraft and thats what two engine data is. We don't use it under EASA as far as I know. Used to depart following the high performance departure SID the same way as Samedan - depart VMC and open the IFR plan once at the 13000 feet which was what you needed to be at, I think it was at 20 D SIO. If you lost an engine you were VMC so continued along the Sion valley and turned right to the lake.

at least we've established what OEI and two engine data is now though eh!

[mutt]

If one was only looking at the difference between 35 feet and 400 feet based on all engines or 1-eng out, then even following an all engine takeoff, retracting the flaps at V2+X, and having an engine failure, the difference in the initial height gain and gradient "should" be sufficient to ensure that you are above the single engine profile..... however, as we have obstacle clearance heights significantly higher than 400 feet, then the concept of selecting flaps up at V2=X is not going to guarantee obstacle clearance, even Gulfstream have stated that ENGINE FAILURE OCCURS EARLY IN THE DEPARTURE CLIMB, CONTINUATION OF THE SID CLIMB ON ONE ENGINE SHOULD NOT BE ATTEMPTED.

So I will continue to follow our present procedures, TT if you ever get an answer from Bombardier stating that they Guarantee that you will clear all obstacles in the flight path if you accelerate to V2+X and retract the flaps regardless of height, and have a subsequent engine failure, then please let us know.

Mutt

[gaunty]

mutt. :ok:

Tom
This gas been an interesting thread and it took a long time to get to the OEI/SID swamp.

I'm with Bingo and Doug, there is a real danger this discussion is leading the innocents to perdition.

I showed where the 400/1500 ft references come from and why the AFM is constructed so.

So, IMHO and it seems Doug's, unless you have precalculated EVERY ONE of the early flap retraction scenarios for EVERY point of the takeoff path, so that KNOW where you are in (or out of ) the obstacle clearance basket, PRIOR to standing up the power levers on take off, you are a candidate for a Darwin Award.

Trying to achieve that ad hoc and in flight might be a bit of an ask don't you think.

So why not take advantage of the enormous amount of resources and brainpower applied to make you safe and efficient.

I'll bet Bombardier send you a copy of the relevant AFM pages, anything else and they effectively give every Bombardier operator license to have at it, I can see the buzzards licking their chops and the liquidators warming up their red pens as we speak. Without seeming to be over dramatic it might even cost the their Type Certificate, which automatically grounds every aircraft of that type.

But I've been wrong before.:eek::ouch:

[tony64peter]

"What next" is on the money. Noise abatement