Take-off power
 

As a SLF, I wonder why economics might influence the safety of the flight. We, all, agree that if maximum available power is used more fuel will be burned, lifetime of the engine will be reduced and tbo eventually reduced. The risk of overstessing the engines might induce failures.

On the other hand, if lesser runway is used, the chance of remaining on the runway after an aborted take-off close to V1 increases.

Shouldn't engines be operated at a compromise setting between maximum power and settings currently used?

I stand to be corrected and would appreciate to read comments from aero engines specialists.

Thks in advance.

They already are. Take Off calculations already allow for a 15% increase in take off run plus a further third of the distance from airborne to 35 feet. How much more margin do you want, and would it make any difference if you've used the wrong weights in your calculations anyway?

Safety margin
 

Thks for your early valuable reply.

Willy

Not so many years ago now, I know of one (now ex-) 707 operator (military, southern hemisphere) whose SOPs on takeoff calculations were that one pilot prepared a set of figures, then handed the books over to the other with the book closed and no pages marked so that the the second pilot had to go through every step again himself, totally independent of the first.

Then they'd compare figures; and if they didn't agree, they'd look for the error.

On the EK 777 fleet, it was very easy to do something similar until progress intervened with the latest arrivals to the fleet not having the two inbuilt electronic flight bags. It was my habit, (and still is on the older aircraft fitted with the two EFBs), to do the takeoff figures myself, and then, with the very handy XFR button, I could very easily compare my figures with the FO's.

However, this doesn't address the problem of the wrong figures being put into the FMS, and I have to admit that I don't do it for every takeoff. On occasions, if there's the possibility of a runway change, I'll have the figures for the second runway in the other EFB pre start so as to save the FO having to be 'head down' inputting the new figures after taxi.

Having said that, I made a comment way back on page 1 of this or the other thread covering this incident that I'll repeat here, if not in exactly the same words. I think there'd be very few professional pilots who would not say "that could never have happened to me", even with every safety measure known to man in place.

As someone has said before me, the two operating pilots, how ever badly they may - (stress, at this stage, may) - have screwed up initially, did an excellent job in revovering the aircraft from the initial situation and then getting it back on the ground in one piece without injuring anyone among their passengers and crew, (I'm sure very ably assisted by the B crew).

I'd like to think I would be able to half as good a job as they did after the initial problem reared its head and pray to God I never have to.

"The ONLY way is for the aircraft to weigh itself and come up with V1 VR and V2 numbers which if more than a few knots out wont let you enter the numbers from the RTOW calculations without giving you a clear warning message first."

Some of the -400 freighters are fitted with this weight and balance system. Perhaps it should be more widespread.:hmm:

Wiley has summed it up!

They stuffed it up...and they quit while they were ahead!

It wont happen to me...but, it could happen to you!...

so, be prepared!!

So you have seen the report Obie have you??? You are so far ahead of everyone else, muppet habibi!! Some colleagues are too quick to hang, draw and quarter their own, simply amazing :=:=

SyB :zzz:

The old Vickers Vanguard ( Merchantman ) was fitted with a " STAN ",
I can´t remember what it stood for. However, as soon as the freighter
moved it displayed a rough indication of weight and trim, which was then
compared with the load/trim sheet figures. It worked perfectly and saved " big mouth ", one of our load controllers, from getting into serious trouble
when STAN indicated a ten ton weight difference. I know it wasn´t perfect, but it was helpful.

As a brand new first-officer in his 1st airline job I was taught by my Training Captain, when the load sheet arrives,to ask yourself "what is V1 and is it logical"? Whilst this was a turbo-prop operation and didn't have the complications of rated thrust or assummed temperature methods or whatever it is called on the Airbus,I asked this question of myself throughout my career.
We know the empty weight of our aircraft,we know the approximate passenger load,(multiply by 100 KGS)we know how much fuel we want.So we know our approximate TOW before we even see a load sheet.The only large variable will be freight.If the difference between my estimated TOW and the load sheet is not the freight or extra passengers THERE IS AN ERROR.
While this method isn't fool proof and V1 can vary greatly with large TOW weight spreads and power settings and runway conditions,it eliminated the weight error possibility and made me think about the logic of my V1 speed.It worked for me throughout my time.
Of course none of this accounts for the added problems of duty time,time zone changes,accumulated fatigue,flight deck preparation interruptions,commercial pressure,company morale,flight operations department integrity,company operating procedures,flight planning,maintenance,MEL's and all the other distractions which the modern airline pilot has to deal with as part of his so called "normal operation".
It was a much safer flight deck preparation when we didn't tolerate interruption to this preparation.
Shooting the messenger will not fix the problem.

Obie, if you say I "summed it up" with the message you read into my post, I have a serious communication problem.

I'm assuming you have your tongue firmly in your cheek with your following paragraphs.

I've read every post in this thread that I can. As far as I can tell, nobody has asked this so far:-

Wouldn't safety be enhanced if every flight started as far away from the far end of the runway as possible? - i.e no starting from intersections with 300m of empty runway behind you.

It might not have made a difference in this accident, and I'm not sure whether or not they did start at the end or part way along the runway. Anyone else got that info?

framer

You said : Here is how I imagine it working; if for example you put the data into the laptop and it came out and said max time to 100kts is 35 seconds. You then trundle out to the runway and roll, at 35secs you notice you are only at 98kts, either abort or TOGA and off you go, if you get to 35secs and you are at 85 kts...abort.


Which is exactly the point I was trying to make. If you do it this way it works - if you measure the time to 100 kts and discover it's actually 45 seconds not 35, what the heck do you do next? Can you be sure you have enough tarmac to stop?

It strikes me that if more departures are going to be made at reduced power using a bigger percentage of the available tarmac for economic resaons, then it's becoming essential to check the progress of the roll, other wise we're going to see more events like EK407.

Here's the spec. for a TakeOff Performance Monitor, published in 1987: sae.org I think that's what we're all asking for? If you have $61 to spare, you can even read it!

I haven't seen the document but I'd assume the problem is a little more complex than you might initially think. However, in these days of GPS and abundant storage/processing power, I'd have thought it would have been possible to construct a device that took as inputs the stabilised N1/EPR from the engines and the flap setting, measured the acceleration (and so determined the mass), then did a quick calculation from knowing (independently) where you were and where the end of the runway was.

If this calculation showed that you wouldn't get airborne in the length available, it would trigger a warning (possibly configuration?). If the warning system was set up so that it would only trigger on recognising a severe performance issue (= impending crash), then there would be much less likelihood of false warnings. The technology is there - certifying such a device is another issue completely...

It's just not possible to do it accurately.
 

Interesting. I did it for 20 years and didn't realize that.

I fly as an F/O on 742 and am a great fan of checking acceleration at 100kts. Though its not a simple calculation as altitude, wind, T/O weight as well as actual performance margin need to all be taken into account. I have an excel program which spits out a value for each Take off which I find accurate to about 3 sec. I start timing as we go through 60% and interestingly the acceleration times vary from 15 - 30 seconds ( I add 2sec for a static T/O ). The greatest variable I find is the F/E technique applying T/O thrust, a problem which won't occur on the new a/c using auto throttle for take off. As I'm in the right seat its will not be my decision to stop however I can at least inform the Capt if the acceleration is way off, possibly he may "feel" it too. I see it as a last resort strategy as I believe if you did mess the figures up you will "feel" that the accelaration is slow and now have a number you can compare it too. And can then make a reasonable decision based on the factors of the day.

Ed,

All I can say is that the lawyers would have a field day if it went to court and all you were able to say is that "it looked right at 100 kts."

Why do so many people have a problem grasping the concept of this extra check?

The point of this check is to insert another safety mechanism on the takeoff roll, in order to prevent an aircraft becoming a very fast mode of ground transport.

In your example, the crew had chosen to commence the takeoff roll, meaning ipso facto that they were happy with their configuration and calculations to do so.

Without any intermediate check, they would have continued the takeoff roll anyway! By this (ficticious for the example) crew saying "...it looked right at 100 kts..." does not have a bearing on the outcome - they were going anyway! Thererefore legally it has no meaning.

The only way the 100 kt check can change the outcome of a departure is for the crew to abort the takeoff, turn around and have another go; after re-assessing their configuration and calculations. Hardly unsafe.

oddly enough you say that, but in truth the 100 kt point is very telling, I always say 100 kts, 30 seconds, now that is my airplane, empty or full, a 747.
I say this because if I have not reached 100 kts by 30 seconds I know two things, either I have incorrect power set for the weight, empty or full, or I have a significant speed reduction, ie dragging brake, etc. Either way I know from time on type I may reach V1, but never VR in the confinements.

Rules of thumb are just that, a gross error check, but they serve the purpose to put doubt in your mind, and if I reach 100 kts and I am 20 seconds, I am stopping, if I reach 100 kts and I am 28 seconds I am very very observant. It cast doubt, and thats exactly what a rule of thumb is intended to do. It alerts you to impending disaster, and you react accordingly, I reach 120 and it still looks odd, I am now stopping.
beyond that, my options are limited.
Thankfully this has always carried me through, I have reached V1, and subsequently VR, albeit sometimes pretty far down the available surface, but it has worked.
I can say, from years of flying heavy aircraft, go oriented is a mindset, but the reality is always that the spread between V1 and VR can mean you may make V1, but never VR.
That is a reality I hope I never encounter.
I can well imagine what these guys saw, I hope to never see it, but I feel that gross error checks have their place, and it is exactly this scenario.

I cannot help but think that reliance on technology has pushed the gross error checks to the side, which may be a shame.

I would never dare to criticize the the crew involved, they acted on what was the information of the day. They now live and die by that inputted information, they undoubtedly believed in what they did at the time. I understand they were high experience, well established crew, unfortunately, as previously stated, you are as good as your last flight.

I suspect that training has shifted to reliance on given information, and it is very easy as crew to take face value information as gospel, I have seen it on occasion, the flight plan gives you a fuel, OK put it on, did you check it vs time and burn? no, it was on the plan, but they realize that they will never make destination.... after they depart.
A gross error check would have caught that, average burn VS FP fuel, for your weight.

We as crew are the final check, not dispatch, not load planners, because guaranteed when the flight goes all wrong, none of them are to blame.

The CPT signs the book, and will be fully accountable, and thats why in my back pocket I always hold a few gross error checks, they may seem old fashioned to those trained on glass, and fully reliant on given information, but they have served me well so far, and I have seen no compelling reason yet to give them up.

Finale?
 

FI reports that the chaps have resigned.

G'day ;)

Indeed Feather#3, as reported in our local rag which, by the way, has used ZK-EBC's photos & credited Pprune.org as the source!

super vc10
 

full length

Man on the ground - thanks for that. So it wouldn't have mattered in this accident. I'd be interested to see others opinions on the question in general. Always use the full length of the runway or not? If not, why not?

Intersection departures are perfectly valid and acceptable...as long as you are not trying to fly half way around the world, ...... and you have the figures available.

I don't have the charts but, from memory, I can see little difference in using the full length of 27 at MEL or departing from the 27/16 intersection on 16. :8

I don't think I would be very popular with the local residents. :E

....so, noise abatement is more important to you than the safety of your 150 or so pax?...is that what you're saying? Or have I misread you? :confused:

I think you have misread me.

Noise abatement is just one (low importance) consideration.

I was merely stating that just because you have 2000 feet or so of concrete/tarmac behind you on r/w 16 it does not make it any less safe than r/w 27 as there is still 8000 feet or so in front of you.

If I was trying to fly an aircraft at anywhere near MTOW, I would of course prefer the longest r/w available.

Thread drift in the prevaling wind.......;)

p.s. Have you never requested/done a takeoff with a slight tailwind in preference to a 3 mile taxi for a slight headwind ? All perfectly safe.

I read on the Melbourne Age Newspaper web site that the have resigned.

This was already reported just six posts above yours, with the additional comment that their source is PpruNe.

:ugh:

The facts ! Both operating pilots were forced to resign following a flight operations debriefing in DXB this week. The management had decided to effectively SACK both guys before the publication of any official reports were published. Following the meeting both pilots were taken into the SVP fleets office where two 'pre prepared' letters were awaiting their signiture ! Both a resignation letter and a confidentiality statement. Both guys were told that failure to agree to resign and sign the letters would lead to legal action against them and were told " thing would get very ugly " for them .Both guys have therefore resigned and have been given approx 3 weeks to pack up their lives and get out of town.

dofus wrote:
And yet the briefest of glances at this airlines internal roster system shows that both crew members are in fact still available for duties for the entire month of April. Nevertheless dofus does seem pretty sure of himself. My gut feeling is that the people who really know wouldn't be posting here.

Seems that some unsubstantiated posts have been made on this board which have been picked up on by the press. Trigger another poster coming along using the press reports (based on PPRuNe postings) as conclusive evidence of what has happened. Kieran Daly and the Melbourne Age as two examples.

Intersection Takeoffs
 

Several things do you no good:

The fuel not taken on

Airspeed already bled off

The altitude above you

The runway behind you.

They used the full length.

Love it.....any more gems, Ed?

Brokenenglish
"The Age" quotes Emirates as the source of the info that the crew resigned. Several posters have confirmed the rumour. What more do you want from a rumour forum?
I put it to you that the absence of any denial by the company, those involved, or any of their colleagues etc.etc. trumps the appearance of their names in the rostering system.

ferris

They may have resigned, but the airlines internal reference system shows not.

The Age credits its photos to PPRuNe and with the continued absence of any official statement within the company I suspect this is where the 'spokesman' they refer to got his information from too.

Bravo Sierra
 

A vortex of flying crap as they and we fight for space up each other.

Weight, V1 etc etc. Maybe the FO got distracted sending a text message? Hard to do whilst driving a car (especially with an Iphone) imagine how dangerous it is while rotating.

Smilin_Ed "Intersection Takeoffs
Several things do you no good:
The runway behind you. "

That's all well and good Ed when you are operating for yourself.

In airlines that I am familiar with, once you hit V1 you go! ie You take off regardless of how much runway is left.

If you acted the hero, and aborted after V1 because you new you had lots of runway left, and if you damaged the aircraft or if anyone was injured, the airline would have your balls and probably your job!

Many operators prefer intersection departures because it saves heaps of time and money.:ugh:

Reduced power take-offs are preferred as they save money as well, and as far as the pen pushers are concerned, providing the minimum amount of overrun is available, that is all that is needed. Why spend more money on the take-off roll than you need to?:ugh:

As pilots, we are between a rock and a hard place. Pilots want maximum performance to use minimum runway to get off the ground earlier to minimise any potential threat, to improve the safety of all. On the other hand, airlines want us to use minimum power, to use the maximum amount of runway, to have the minimum theoretical safety margin, to save money. :{
Of course the decision to use max power is always up to the PIC, however any pilot who chooses to go against the company SOP (as shown up in the quick access flight data recorder) can expect a "please explain" from the relevant manager and possible job loss.

Unfortunately the decision to use reduced power or not (or an intersection departure (that was not the case here)) is not as simple as it should be. The decision not to abort after V1 can also be questioned.

Upon reaching V1, the pilots of EK407 would have been expecting everything to continue as normal. At VR (I assume they got to that too) they would have pulled back and expected to lift off as it has always done. When lift-off did not occur, the PIC and EFFO would have faced a very unusual situation as to "what to do now"? Correctly, and this should be applauded, they decided to continue and apply TOGA thrust (apparently, from other posts) and avoided a disaster that could have cost many lives and the future of EK as an airline.

Sure, these pilots may have made a mistake with their data input, but their company SOP's should have prevented this error. There were 4 pilots on deck at the time so if there was any gross error someone should have seen it.

Unless this is a case of gross negligence, which I doubt, and if it is found that the EK SOP's were part of the cause, I hope the pilots are re-instated and are shown as true hero's for carrying out a successful recovery and preventing injury to all passengers and crew, after a "faulty" take-off.:ok:

In fact, the point is not so much fuel saving. By reducing T/O power, you will not only extend your roll, but also reduce the climb rate until selection of climb power. So you will remain at lower altitudes for a little longer, where the engines tend to use more fuel than they have to.

The thing that makes a reduced power T/O save money is the reduced wear on the engine. By reducing power, you will also reduce RPM and most importantly the exhaus gas temperature that the turbine has to digest. Consequent use of reduced power thus has the ability to extend engine lifetime and therefore saves rather on maintenance costs than on fuel.

Tu.114

Broken English you are persisting on this forum and others with your roster argument re: the fate of the operating crew. My roster says I will do many things before the end of the month yet I know it will change, so too for the 407 crew. If you resign you are not automatically taken off the roster and I would suggest that this is why you still see duties for this crew, but they will not be doing them. I assure you that what Dofus says is true and request that you give it a rest.