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Kiwi B777 burst 12 tyres in aborted takeoff at NRT

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Kiwi B777 burst 12 tyres in aborted takeoff at NRT

Old 12th Feb 2010, 17:52
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ASRAAM

Gentlemen,

Setting aside this particular incident there is a fair amount of rubbish being talked on this thread about 777 take off performance.

When V1 is determined for a particular take off it will always be safe to go above this speed following an engine failure and it will always be safe to stop below this speed. (Assuming no multiple failures!)

Usually in a 777 V1 and Vr will be coincident, sometimes there will be a small gap. If an increased climb performance is required it may be a large gap.

From a pilots view the difficulty is that you have no idea what the go speed and the stop speed actually are, only that V1 is between them. On some days it would be safe to continue 20 kts (or more) below V1 and on some days it would be safe to stop 20 kts (or more) above V1. YOU JUST DONT KNOW!
Thanks for that

I wonder if with so few posts you could be urged to repost your quote everytime we get into these kinds of discussions
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Old 13th Feb 2010, 05:09
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"Tosh!

If they were accel stop field limited then they would be off the end."


Exactly my point! Depending on what the limiting factor was, they may or may not be off the end, where in a true balanced field calc. they would have been. Tosh yerself!

BTW, how do you get the nice blue background when doing a quote of someone else's offering?
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Old 13th Feb 2010, 06:18
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Even if you ARE ASDA linited, there are significant saftey margins built into the calculations, so it is still presumtuous to say you would definatley be off the end.

ASRAAMs point is well taken, but to me the thing is it really makes no difference. You should continue the takeoff after V1 if it is at all possible. If you have a truley unflyable malfunction, it is better to go off the end at low speed than dig a crater beyond the boundary....
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Old 13th Feb 2010, 06:46
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Wizofox. Well said. These things are seldom perfectly cut and dried. It looks in this case (if the speculation is true) that an above V1 abort was successfull on what had to have been a heavy a/c.
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Old 13th Feb 2010, 07:45
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so was the A/P engaged or not - seems Boeing think it happens enough to be issuing a mod the the engagement logic... was it the case here...? if this has been answered ignore me - I just could not find it on the posts...

WJA
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Old 13th Feb 2010, 14:15
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@5LY

BTW, how do you get the nice blue background when doing a quote of someone else's offering?
copy paste the quote into
[...QUOTE][/QUOTE...]
without the ... s

But,
Exactly my point! Depending on what the limiting factor was, they may or may not be off the end, where in a true balanced field calc. they would have been. Tosh yerself!
isn't true.

If they did a balanced field and Stopway was available then they may well be able to stop after V1 using the stopway that wasn't included in the calculation.

I would say if they used V1max or took off at MTOW Field limited using an unbalanced calculation then they would definitely be off the end if they tried to stop above V1 but for any other calc the jury is out.

However, you have to be pretty sure you can't fly to risk trying to stop. Lots of cases of rejecting above V1 ending in death. Not many cases of going ending the same way.
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Old 13th Feb 2010, 18:14
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Well .. even if their calculations (EFB?) indicated maximum thrust reduction with maximum use of the ASDA, there is a bit of margin built into the procedures (though not advertised!), a.o.:
  • Reverse Thrust: (FAR/CS 25.109) from a dry RWY no reverse thrust is taken into account (idle forward thrust), so any reverse thrust would have decreased the ASDR;
  • Reaction times: (FAR/CS 25.109) depending on certification limits used (amdt 25-42/92), the certified reaction times [1-2 secs recognition/accel time, brake (1 sec), spoilers (1 sec) - dry] provide a bit of margin;
  • Conservatism when using a reduced thrust takeoff: actual thrust will be higher than the rated thrust at the assumed temperature, because the actual air density is higher; actual true airspeed will be lower, because the actual ambient temperature is lower; lower true airspeed combined with the higher thrust will result in a shorter ground distance
So, if you want to perform a post-V1 abort (once again:), you still stand (a bit of) a chance when departing from a dry runway ... much more than from a wet or contaminated runway!
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Old 13th Feb 2010, 19:18
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Re #64 “ there are significant safety margins built into the calculations … ”.
This depends on how you define significant; in comparison with the safety factors used for landing, the RTO factors could be considered ‘marginal’ – and note how often we mess up landings with margin. Also if you wish to rely on the timing margins in certification, then you have to be very well drilled (and resistant to surprise).
The apparent safety margin in some non engine related RTOs near V1 might be attributed to the availability of all engine reverse, whereas an engine failure RTO would not have the same stopping capability.

Re: ” If you have a truly unflyable malfunction … ”.
The phrase ‘unsafe or unable to fly’ is in many SOPs and is often quoted in forum discussions, but has the industry really thought through what this means?
The phrase appears to have originated with the Take Safety Training Aid (TSTA), Boeing / FAA circa 1993. Here it specifically refers to after V1 “… unless the pilot has reasons to conclude that the aircraft is unsafe or unable to fly. ” para 2.3.1.2.
What reasons have been considered and how would these be identified with sufficient certainty to entertain a late RTO with a high risk of overrun; perhaps the observation in #46 ”If the aircraft cannot be rotated, self-preservation will probably dictate that you abort”, defines the only realistic circumstance - and you don't need an SOP for that.

The TSTA modifies the problem by including the phrase (in later sections and simulator briefings) amongst the reasons to reject in the low speed region. In addition it complicates the issue further at high speed before V1, with the qualification “the perception that the aircraft is unsafe or unable to fly”. Does the industry accept that a high speed RTO can be based on the perception of safety without indication, as opposed to an engine failure / fire which can be confirmed from instrument displays and warnings?

In thinking about unsafe or unable to fly, also consider other items as reasons for rejecting in many SOPs – nosewheel vibration, or tire failure where debris may have damaged the aircraft. Again how can the crew know that a vibration is from the nosewheel – experience, simulator training? Or that the bang was a tyre failure and that debris have cause damaged? To have some certainty, perhaps confirmatory evidence is required from engine or systems displays – essentially the same indications to crosscheck an engine RTO event; thus SOPs could perhaps be simpler.

Some (most) SOPs attempt to cover a range of situations, but fail to consider how the crew can meet the requirements in the SOP.
At best, many of the decisions which should be based on assessment rely on perception, which is notably weak particularly in stressful and time limited situations. Whereas a warning and confirmatory display provides a good basis for understanding the situation.
Also, consider the choice of action, which should be a simple Go / No Go choice; this may now involve an assessment of the risks within that choice because the wording of the SOP places the responsibility on the crew for evaluating the risk in the choice.
RTOs are one of the few areas in operation where the choice of action should be self-evident from the situation assessment – is there a ‘reasonable’ failure, what is the speed in relation to V1; decision Go / No Go, the risks are bounded by certificated performance and correct crew actions. Unfortunately life is not clear-cut, - as related by ‘eckhard’ (#40); we require experience, naturalistic decision making, airmanship, etc, but not more complexity in SOPs.

Perhaps removing the ‘what if’ scenarios from the reasons to reject would reduce the occurrence of weak assessment or poor choice of action; particularly if these scenarios are already covered by the assumptions in the basis safety for aircraft certification (FAR/CS), i.e. systems and control redundancy. What is the probability that such an event (what if) will be encountered in operations? The TSTA did not identify any event where an inappropriate RTO would have resulted in the aircraft being unable to fly.

“It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that ain’t just so.” Mark Twain.
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Old 13th Feb 2010, 19:39
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safetypee

Perhaps removing the ‘what if’ scenarios from the reasons to reject would reduce the occurrence of weak assessment or poor choice of action; particularly if these scenarios are already covered by the assumptions in the basis safety for aircraft certification (FAR/CS), i.e. systems and control redundancy. What is the probability that such an event (what if) will be encountered in operations? The TSTA did not identify any event where an inappropriate RTO would have resulted in the aircraft being unable to fly.
I heartedly concur with you on this. Unfortunately decison making is what pilots are for. Even on boards like this the majority of posts have to do with second guessing without all the cues or facts. I fear that broad what-if discussions only reinforce a pilots desire to take the time to make thought out decisons even when the time factor means it should be done by rote.
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Old 14th Feb 2010, 22:28
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lomapaseo. "decision making is what pilots are for ”, what a novel and refreshing view.

The time factor in decision making for RTOs is a central issue.
In the low speed zone, there is relatively more time and thus there may be a wider range of situations which can be considered. In this zone, the pilot may be able to use knowledge based thinking – evaluate the situation, options, and risk; where the additional time or any extension of it into the high speed zone should not be hazardous. Thus, operators should maximise human attributes – allow the pilot to think and make decisions. There may be no need for a SOP here, only guidance and information as to hazard, risk, etc.

In the high speed zone, a well constructed SOP should enable a quick and clear assessment leading to ‘rule based thinking’ for the choice of action, perhaps only considering an engine failure or fire, for which performance is optimised for.
Training has to provide practice in assessment (things not to consider, just as much as those which are important). Currently there is over focus on the actions. Both actions and thinking (the assessment) are important, they need to be developed as a skill, or at lest a semi automatic processes. The critical aspect is to prevent the thinking process extending beyond V1 where the risks from ‘late’ actions increase rapidly.
In addition, pilots have to develop the ability to manage surprise and the stress from unexpected symptoms.

Much of modern training is based on the human as a hazard, whereas if we saw humans as the generators of safety (James Reason) and use them in this way, then SOPs might be simpler. The industry depends very much on the human to rescue the rare and surprising event – perhaps as in this thread, the incident involved unique assessment decisions, most probably based on experience, to enable a safe outcome.

”The greatest mistake that a man can ever make is to be afraid of making one”. Elbert Hubbard.
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Old 15th Feb 2010, 03:01
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My sources tell me the A/P was engaged and the S/O called the abort.
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Old 15th Feb 2010, 05:23
  #72 (permalink)  
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minimum_wage;
My sources tell me the A/P was engaged and the S/O called the abort.
This is a matter of terminology I guess, but the third pilot, where carried, is commonly known a Relief Pilot or Cruise pilot. The Captain, nobody else, calls the reject, unless it's a training situation with the training captain in the right seat. That situation calls for very clear understanding as to who will reject the takeoff and crisp cockpit discipline.

safetypee;

I'm sure you will have pondered this already, but in circumstances such as an inadvertent autopilot engagement on the runway during takeoff where it may not be known until the control column is moved rearwards for the purposes of the rotation manoeuvre that the control column cannot be moved due to such engagement, I think you will agree that there is no time to consider if the autopilot would disengage such that rotation can be executed. I don't know what the right answer is nor do any of us, for sure. By definition, Vr is past V1, and keeping the above comments from ASRAAM in mind, and your comments, thus:
Perhaps removing the ‘what if’ scenarios from the reasons to reject would reduce the occurrence of weak assessment or poor choice of action; particularly if these scenarios are already covered by the assumptions in the basis safety for aircraft certification (FAR/CS), i.e. systems and control redundancy. What is the probability that such an event (what if) will be encountered in operations? The TSTA did not identify any event where an inappropriate RTO would have resulted in the aircraft being unable to fly.
, and the TSTA statements, “… unless the pilot has reasons to conclude that the aircraft is unsafe or unable to fly. ” (para 2.3.1.2), as well as the FAR/CS for the aircraft, I would concur with reducing the reasons/requirements for a reject above 100kts, I would acknowledge the SOPs as providing the legal freedom, (not authority - the captain already has that), to conduct a reject for "unsafe/unable-to-fly" reasons but would suggest that not all such circumstances have been examined which would provide guidance for crews rejecting for this last category.

A Canadian Airlines DC10 rejected a takeoff right near V1 in Vancouver due to a loud, explosive noise which turned out to be a compressor stall. The aircraft overran the runway and while substantially damaged, all evacuated successfully. In the context of this thread, it is worth quoting the Canadian TSB Report briefly:
The captain's decision to reject the take-off was based on his perception of the circumstances. The influences that could have shaped his understanding of the situation were his training and experience, his perceptions as to flexibility provided by the use of C2B power, and the available visual and aural cues. In addition, the wording contained in the CAI DC-10 FCOM, that a "further 3 seconds is allowed until full braking with spoiler actuation is attained," may be ambiguous in that it implies that some time beyond V1 is available for the pilot reaction. The limited published information regarding the inevitability of an overrun when a take-off is rejected beyond the V1 speed could also lead to this adverse consequence not being considered in the decision to reject.

The captain's understanding was that an engine failure would not be an adequate reason to initiate a rejected take-off after V1. In this case, however, prior to making his reject decision, he did not see or perceive indications, or hear advice from his crew, that an engine failure had occurred. Also, the loud bang was neither similar to any compressor stall symptom that he knew about, nor similar to sounds that he had heard in training or experienced during actual flying.

All the members of the flight crew reported that the sound was unlike anything they had heard before. Not only was the bang very loud, but it was difficult to specify its point of origin. None of the crew saw the engine fail light illuminate<23>, nor did they notice the drop in N1. The only cue the captain received to indicate that the take-off was no longer normal was the loud bang, followed by a series of thuds and vibrations. Because the situation did not match any of the captain's previous training or actual flying experience, he was required to respond instantly to the situation by drawing on whatever knowledge or other experience he had.

When the captain heard the loud bang, he immediately thought of a bomb. The only procedural guidance available for this circumstance was that a rejected take-off after V1 could be initiated when "the captain believes that the aircraft has suffered catastrophic failure and will not fly." According to the captain, his action was probably also influenced by the fatal DC8 occurrence that he had witnessed and which resulted in his mental rule of thumb that if structural failure were suspected, he would not take the aircraft into the air.

When the captain decided to reject the take-off, it was his correct belief that, because they were using C2B power figures, the aircraft would have reached the 164-knot V1 earlier, and that there would be additional runway available for the reject. Based on this fact and his visual impression of the runway available, he was confident that the aircraft would be able to stop on the runway.
To my knowledge and all previous experience in rejected takeoffs executed in the simulator, no training nor discussion was provided for other than engine failure or fire at some point in the takeoff. Sometimes a loud noise accompanied an engine failure. There was never the "unsafe to fly" factor introduced which was intended to cause a reject. I suspect this is the case with most simulator recurrent sessions because that is what is examined in IFR and PPC (for others, Pilot Proficiency Checks - aircraft-specific procedures) rides.

Just to complete the discusssion along this line, I can recall one session where, in the A320, the Captain's sidestick went u/s, (there is now a Master Caution but if I recall, there was none at the time, (18 years ago) and when I went to rotate nothing happened. Control was instantly given (commanded) to the F/O, with the word, "Rotate" and that was that. Had we rejected, we would have overrun - had the F/O's sidestick also been inoperative we would have been in trouble.

So....I should think that, under the circumstances of this reject (Tokyo ANZ B777), a control column that would not permit movement aft would be accompanied by exceptional surprise and an instantaneous decision, which, in this case, was the correct one because it worked and which would take the engineers and aerodynamicists months to tell us why, which would almost certainly not be sufficiently applicable to another case of autopilot engagement, should it occur.

Which returns us to the original point above concerning what necessarily renders an aircraft unsafe to fly and what should not be cause for a reject even when surprise is the primary motivating factor?

There is already good guidance on tire failure, (continue, due reduced braking and a full runway for landing), but not on shrapnel damage so it is always a guess and experience cannot lend too much of a hand. Do we "triage" the event by computer-projecting various tire delaminations? Any such work must include degradation of warning systems as well as structural parts. In Toronto, a DC9 overran a runway in 1978 when one of the red gear unsafe lights came on as a result of a tire delamination which damaged the gear proximity warning switches and also caused initial failure of one of the engines, (which recovered after the reject decision was made). The decision to reject was made very near V1 on a max-gross takeoff and the aircraft overran into the same gulley that AF overran into a couple of years ago.

Do we examine flap structures for flyability after substantial damage? Again, there are cases which may apply.

Your original point however is key; are the goalposts moving within airline operations departments without substantive research, and are certification standards fully comprehended by both airline flight operations departments and crews? While certified performance is always pristine in terms of substantiation, we all know that actual rejects are far messier and unpredictable. The narrowing of factors which should cause a reject becomes a single point at V1 - what that point is in terms of engine performance is well understood, relatively clear and trained for; what the point is for aircraft performance and "flyability" is not researched so there are no rote procedures for guidance and therefore relies almost solely on those factors observed in posts above: experience.

PJ2

Last edited by PJ2; 15th Feb 2010 at 15:20.
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Old 15th Feb 2010, 05:41
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Just for accuracy's sake, there is no "S/O" on any airliner these days,
Qantas, Air New Zealand, Cathay and several other airlines employ Second Officers (S/Os) who occupy control seats during cruise only, are in Jump seats for T/o and landing, and are entitled to call deficiencies as part of CRM practices.

So you'd be wrong there.....

Just recieved a communication stating that a software fix is on its way due to "A number" of cases of inadvertent A/P engagement on the ground, with consequent unexpected control forces, which had led to RTOs above V1, so I give some credence to that idea here.
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Old 15th Feb 2010, 07:07
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[QUOTE]Just for accuracy's sake, there is no "S/O" on any airliner these days, and the Captain, nobody else, calls the reject, unless it's a training situation with the training captain in the right seat.[QUOTE]

What sort of screwed up airline only lets the Skipper call an abort? Never come across that one before.
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Old 15th Feb 2010, 08:15
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What sort of screwed up airline only lets the Skipper call an abort?
Ours, for one.
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Old 15th Feb 2010, 09:00
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PJ2,

Just for accuracy's sake, there is no "S/O" on any airliner these days, and the Captain, nobody else, calls the reject, unless it's a training situation with the training captain in the right seat. That situation calls for very clear understanding as to who will reject the takeoff and crisp cockpit discipline.

For your own accuracy, I fly for Air NZ so I should know. I'm not a Captain and I have called a reject before.
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Old 15th Feb 2010, 09:39
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What we call an FE the Americans call a SO
What we call an SO the Americans call a cruise pilot

Maybe thats where the confusion lays
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Old 15th Feb 2010, 10:21
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Well, when I flew in the USA, we had FEs AND SOs. The FEs were professional flight engineers and the SOs were second officer pilots peforming at the FE's panel while waiting to get into the right hand seat.

I have also heard of ROPES (Retired Old Pilots Engineer's Station). This was a wheeze which kept old captains employed beyond retirement age.

Confusing isn't it?
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Old 15th Feb 2010, 11:24
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What sort of screwed up airline only lets the Skipper call an abort? Never come across that one before.

Not getting confused with - anyone can CALL the abort....but ONLY the Captain makes the decision on whether to abort or not.
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Old 15th Feb 2010, 13:37
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I always thought that it was important for only the two guys at the controls to know who who calls the abort and unimportant/ambigous to anybody else
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