EK407 Tailstrike @ ML
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Loose liver - lets have your in depth analysis then.
Mr. Ed - Some significant thread drift with your "off beat" comments.
To me, a likely scenario with this event is:
1. The crew at some stage may have extracted laptop speeds and FLEX using ZFW as TOW.
2. The FMGC may well have contained the correct weight data (from the flight plan).
3. The PERF T/O page had the incorrect V speeds from the laptop.
4. The crew rotated at the incorrect (low) Vr to a normal pitch attiude.
5. The aircraft flap configuration and speed was inappropriate for flight.
6. When the aircraft wouldn't become airborne, the pitch attitude was increased and the aircraft had a severe tail stirke with possible multiple contacts.
7. The higher FLEX temperature combined with tailstrike drag contributed to the long ground roll.
8. TOGA thrust was probably selected at some stage.
The crew did a remarkable job in a very dynamic situation. After all, they were expecting the aircraft to fly off after rotating at the Vr speed in the PERF T/O page. They were confronted with a situation about which they had no experience. What would we all do ? I wouldn't like to be there.
There probably is an error component on the part of the crew with respect to cross checking (no idea what the EK checking procedure REALLY is) . But I bet there are much greater systemic issues for which management and the company must take responsibility.
I hope the Australian ATSB is able to overcome Dubai Inc. in arriving at a final report that tackles the difficult and overriding issues of corporate errors and cover ups.
As a final comment, it's probably now worth including SIM sessions that look at this type of event, and also maybe having an idea of what the V speeds should roughly be at heavy weights.
Discussion about V1 > Vr has no place here.
Mr. Ed - Some significant thread drift with your "off beat" comments.
To me, a likely scenario with this event is:
1. The crew at some stage may have extracted laptop speeds and FLEX using ZFW as TOW.
2. The FMGC may well have contained the correct weight data (from the flight plan).
3. The PERF T/O page had the incorrect V speeds from the laptop.
4. The crew rotated at the incorrect (low) Vr to a normal pitch attiude.
5. The aircraft flap configuration and speed was inappropriate for flight.
6. When the aircraft wouldn't become airborne, the pitch attitude was increased and the aircraft had a severe tail stirke with possible multiple contacts.
7. The higher FLEX temperature combined with tailstrike drag contributed to the long ground roll.
8. TOGA thrust was probably selected at some stage.
The crew did a remarkable job in a very dynamic situation. After all, they were expecting the aircraft to fly off after rotating at the Vr speed in the PERF T/O page. They were confronted with a situation about which they had no experience. What would we all do ? I wouldn't like to be there.
There probably is an error component on the part of the crew with respect to cross checking (no idea what the EK checking procedure REALLY is) . But I bet there are much greater systemic issues for which management and the company must take responsibility.
I hope the Australian ATSB is able to overcome Dubai Inc. in arriving at a final report that tackles the difficult and overriding issues of corporate errors and cover ups.
As a final comment, it's probably now worth including SIM sessions that look at this type of event, and also maybe having an idea of what the V speeds should roughly be at heavy weights.
Discussion about V1 > Vr has no place here.
Last edited by strobes_on; 6th Apr 2009 at 00:45.
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Strobes, no in-depth analysis from me sorry; I don't claim to have superior knowlege on the topic. But I do have a question:
Why isn't there an error message generated when ZFW is used in place of TOW?
Why isn't there an error message generated when ZFW is used in place of TOW?
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If Vr is reach as no V1 has yet been encountered, then V1=Vr.
Happens many times ... For you on that day too much asphalt for nothing.
I believe both guys were as full back stick they could ...
Happens many times ... For you on that day too much asphalt for nothing.
The crew did a remarkable job in a very dynamic situation. After all, they were expecting the aircraft to fly off after rotating at the Vr speed in the PERF T/O page. They were confronted with a situation about which they had no expereince. What would we all do ? I wouldn't like to be there.
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It all sounds like russian roulette for the PASSENGERS ,,, management telling the pilots how to suck every joule of energy out of every gram of fuel , saving pennies here and dimes there and creating a condition wherin factors lead to increased holes in the cheese model of accident investigation !!!
Put the friggen throttles to MAX take-off power, get off the ground and get climbing early THEN think of saving pennies here and dimes there,,,looks like the cart is ruling the horse NOW !!!
Put the friggen throttles to MAX take-off power, get off the ground and get climbing early THEN think of saving pennies here and dimes there,,,looks like the cart is ruling the horse NOW !!!
I think that your V1 exceeding VR calculation is coming out of performance charts for a certain environmental envelope and maximum certified weights.
If you don't meet these conditions and VR is lower, your V1 is decreased to meet VR.You abort at VR all performance calculations are VOID regardless of V1.
I have seen these charts where our V1 speed would have us airborne and flying almost at V2!
If you don't meet these conditions and VR is lower, your V1 is decreased to meet VR.You abort at VR all performance calculations are VOID regardless of V1.
I have seen these charts where our V1 speed would have us airborne and flying almost at V2!
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blueloo
Minimum thrust/Maximum reduction depends on several factors including aircraft and engine combination, company preference and regulating authority.
Using one operator's B747-400 for example:-
Fixed Derates of 10% and 20% are available which may then be subject to Assumed Temperature Derates of up to 25%. This gives a maximum reduction of up to 40% from Rated Thrust.
Using 100,000 lb as Rated Thrust makes the sums simple for this example:-
Max Thrust. 100,000 - up to 25% Assumed Temp Reduction = 75,000
10% Derate . 90,000 - up to 25% Assumed Temp Reduction = 67,500
20% Derate . 80,000 - up to 25% Assumed Temp Reduction = 60,000
Oh for a B747-400 with 4 x 100,000 lbs of thrust ! like
off a shovel
You will understand that even on a 4km runway, any significant thrust reduction from that required will fail to accelerate the aircraft sufficiently for normal flight.
Minimum thrust/Maximum reduction depends on several factors including aircraft and engine combination, company preference and regulating authority.
Using one operator's B747-400 for example:-
Fixed Derates of 10% and 20% are available which may then be subject to Assumed Temperature Derates of up to 25%. This gives a maximum reduction of up to 40% from Rated Thrust.
Using 100,000 lb as Rated Thrust makes the sums simple for this example:-
Max Thrust. 100,000 - up to 25% Assumed Temp Reduction = 75,000
10% Derate . 90,000 - up to 25% Assumed Temp Reduction = 67,500
20% Derate . 80,000 - up to 25% Assumed Temp Reduction = 60,000
Oh for a B747-400 with 4 x 100,000 lbs of thrust ! like
off a shovelYou will understand that even on a 4km runway, any significant thrust reduction from that required will fail to accelerate the aircraft sufficiently for normal flight.
Last edited by Sir Richard; 6th Apr 2009 at 08:14. Reason: Reformatted for clarity
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It all sounds like russian roulette for the PASSENGERS ,,, management telling the pilots how to suck every joule of energy out of every gram of fuel , saving pennies here and dimes there and creating a condition wherin factors lead to increased holes in the cheese model of accident investigation !!!
Put the friggen throttles to MAX take-off power, get off the ground and get climbing early THEN think of saving pennies here and dimes there,,,looks like the cart is ruling the horse NOW !!!
Put the friggen throttles to MAX take-off power, get off the ground and get climbing early THEN think of saving pennies here and dimes there,,,looks like the cart is ruling the horse NOW !!!
Its not just about saving pennies - its about longer engine life, and less exposure to max temps/high egts etc, will hopefully mean less chance of the engine exploding/catastrophic failure on some dark and stormy night at MTOW.
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Its not just about saving pennies - its about longer engine life, and less exposure to max temps/high egts etc, MTOW.
will hopefully mean less chance of the engine exploding/catastrophic failure on some dark and stormy night at
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Longer life = pennies
it also pennies here. It means that more parts have to be changed more often to avoid the possibility of exploding/catastrophic failure. The end sum is the number of hours that the engine operates at max trust and take off power
Both points have been mentioned before.
I still however maintain that less exposure to higher egts and more frequent max thrust means less chance (not no chance) of catastrophic (or even partial) engine failure. Yes, it means more frequent part changes and more cost - but in the intervening periods the engine is still exposed to more extremes.
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Better not let FrequentSLF see the airlines fuel policy ! That we actually take off with less than full tanks - sometimes half tanks, sometimes quarter tanks!!
This post added a lot to the discussion.
Make sure that you do not confuse pounds with kilos when you refuel and you have installed the right fuel gauge.
back to the thread
blueloo
but in the intervening periods the engine is still exposed to more extremes
The guys in front know what they are doing. However I have a very simple question. If not driven by company policy, would you or not use always max trust?
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Sir Richard
All very well with the figures but it might be a bit more helpful if you stated what engine type you are referring to ie. RR, GE. or PW, as they are different figures (de-rate percentages) without getting into pedantics.
Cheers
JO
Cheers
JO
Last edited by judge.oversteer; 6th Apr 2009 at 16:37.
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Some people on this thread seem to be implying that an intersection takeoff is akin to negligence or poor airmanship.
There are many reasons for intersection takeoffs. Some airports like Chicago and Newark sometimes promulgate on the ATIS that the takeoff will be from an intersection. At other airports like in the Caribbean full length may result in a tricky 180 degree turn at night on a limiting runway, get that wrong and you may close the airport and isolate the island for 24 hours. The 180 degree turns can scuff the main gear badly and if only for a gain of 300 meters it is not worth it. I find those 180 degree turns in a wide bodied Boeing more stressful than any takeoff.
On rare occasions I have used intersection takeoffs to jump a queue, to avoid an aircraft that has stopped on a taxiway with a problem, to make a tight slot, to reduce taxy time or to avoid a tight wingtip clearance situation with a remotely parked aircraft. This is commercial operation. I would not do an intersection takeoff if there was no justification behind it. For those who expound the "runway behind you is useless" mantra if it is perfectly safe to takeoff from the full length of a 2500 meter runway it therefore must be equally safe to take off under the the same conditions 500 meters along a 3000 meter runway. The takeoff is either legal or not legal. Full length with the wrong takeoff data as in the EK case is not safe. An intersection takeoff with the correct figures is safe and legal.
There are many reasons for intersection takeoffs. Some airports like Chicago and Newark sometimes promulgate on the ATIS that the takeoff will be from an intersection. At other airports like in the Caribbean full length may result in a tricky 180 degree turn at night on a limiting runway, get that wrong and you may close the airport and isolate the island for 24 hours. The 180 degree turns can scuff the main gear badly and if only for a gain of 300 meters it is not worth it. I find those 180 degree turns in a wide bodied Boeing more stressful than any takeoff.
On rare occasions I have used intersection takeoffs to jump a queue, to avoid an aircraft that has stopped on a taxiway with a problem, to make a tight slot, to reduce taxy time or to avoid a tight wingtip clearance situation with a remotely parked aircraft. This is commercial operation. I would not do an intersection takeoff if there was no justification behind it. For those who expound the "runway behind you is useless" mantra if it is perfectly safe to takeoff from the full length of a 2500 meter runway it therefore must be equally safe to take off under the the same conditions 500 meters along a 3000 meter runway. The takeoff is either legal or not legal. Full length with the wrong takeoff data as in the EK case is not safe. An intersection takeoff with the correct figures is safe and legal.
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Better not let FrequentSLF see the airlines fuel policy ! That we actually take off with less than full tanks - sometimes half tanks, sometimes quarter tanks!!
Economics are part of life, and in aviation we balance risk vs reward.
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Some people on this thread seem to be implying that an intersection takeoff is akin to negligence or poor airmanship.
To use an extreme example: imagine the runway is fifty miles long. Is it safe to use the intersection halfway down? That would leave twenty five miles. But what about using the runway behind you? Obviously that would be a stupid waste of time and fuel. So in this case all of sane disposition would agree that an intersection departure is appropriate. Now that I have you all in my net, lets start reducing the size of the runway. At some length it will become inappropriate to do an intersection departure. This point will be subjective but for those of us who fly commercially it will be at least a length calculated to provide an adequate margin of safety.
This has nothing to do with the original thread by the way.
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f not driven by company policy, would you or not use always max trust?
Also a low altitude level of would be fairly uncomfortable for pax from a max thrust takeoff at low weights.
Even with a fairly decent pad/buffer we can get a derated takeoff near the MTOW at times.
have I got your message right, Ed? You're suggesting there's someone out there (you?) who'd sit there and conduct a pre-takeoff brief that included the gem that he would abort AFTER the nose wheel was off the ground?
I seem to remember this all started when I suggested that intersection takeoffs are not smart because you have discarded some of your safety factor. SOP won't save you in court.
Would you,or not use max thrust -
No. Not if I had the choice. In a lightish weight large jet (certainly with 4 engines), and you were to use max thrust and an outboard engine let go at say 50kts - you would not be able to keep it on the runway - you would go off the side - fact! Full power can increase the risk if it is not required.
No. Not if I had the choice. In a lightish weight large jet (certainly with 4 engines), and you were to use max thrust and an outboard engine let go at say 50kts - you would not be able to keep it on the runway - you would go off the side - fact! Full power can increase the risk if it is not required.