4th June 2010 B737-800 rejected takeoff after V1 Report is out
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Hmmm! ...I must remember that!
The next time I face an abnormal or an emergency situation I shall make a PA and seek assistance from the great unwashed down the back!
The next time I face an abnormal or an emergency situation I shall make a PA and seek assistance from the great unwashed down the back!
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Pininstauld:
I am sorry, but the outcome does not prove or even say anything about the judgement. During the takeoff roll, I am certain, there was no way for the FO to calculate ( or even estimate profoundly) the remaining rwy in relation to an increasing energy state and therefore towards stopping margin. His judgement was not proven correct, it was pure luck and chance. Aborting after V1 means you have completeley left the calculated, controlled operation of an aircraft and the outcome is depending on luck.
Now that I can agree with - exactly what I mean.
I just don't understand how you can write the first sentence I quoted and then follow it by this one closely after.
I find this abort hairraising, potentially desasterous and ignorant of risk factors involved.
The runway was 3,000 metres and his judgement was proved correct because it came to rest half a kilometre from the end of the pavement.
The roulette wheels came up with the right result this time because there were no casualties - and that's really all that can be said.
I just don't understand how you can write the first sentence I quoted and then follow it by this one closely after.
I find this abort hairraising, potentially desasterous and ignorant of risk factors involved.
Aborting after V1 means you have completeley left the calculated, controlled operation of an aircraft and the outcome is depending on luck.
The stop is not an event controlled by random chance ergo by definition luck does not play a role.It is an event the outcome of which can be estimated (obviously not as well as it can be calculated.).
checkboard
Slight quibble
The ability to stop .... is not an event controlled by random chance .... etc.
However the outcome appears to be based on pilot skill e.g. 95% sucess
Rubbish. 
The stop is not an event controlled by random chance ergo by definition luck does not play a role.
The stop is not an event controlled by random chance ergo by definition luck does not play a role.The ability to stop .... is not an event controlled by random chance .... etc.
However the outcome appears to be based on pilot skill e.g. 95% sucess
Whatever happened to the concept of "Thinking" while you are set there in the front end? Rote following the SOP's/Emergency Procedures kills folks just as dead as failing to follow them.
Case In Point....Chicago, American Airlines...engine departs the wing takes out forward edge lift devices....Crew adheres to the procedure...Altitude over airspeed....on a very bright clear blue day with no obstructions anywhere near them....result....a very dramatic crash fatal to all aboard.
You pin heads that cannot differentiate between a reasoned decision based upon the circumstances extant and some silly argument about SOP's, Seniority, Rank, and who is the damn Boss....just need to wake up and smell the coffee.
If you become slave to a checklist....you are not an Aviator...just a high paid button pusher.
Case In Point....Chicago, American Airlines...engine departs the wing takes out forward edge lift devices....Crew adheres to the procedure...Altitude over airspeed....on a very bright clear blue day with no obstructions anywhere near them....result....a very dramatic crash fatal to all aboard.
You pin heads that cannot differentiate between a reasoned decision based upon the circumstances extant and some silly argument about SOP's, Seniority, Rank, and who is the damn Boss....just need to wake up and smell the coffee.
If you become slave to a checklist....you are not an Aviator...just a high paid button pusher.
Case In Point....Chicago, American Airlines...engine departs the wing takes out forward edge lift devices....Crew adheres to the procedure...Altitude over airspeed....on a very bright clear blue day with no obstructions anywhere near them....result....a very dramatic crash fatal to all aboard.
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SASless
Tell me where the reasoned decision was made by the FO in this case because there is NO evidence in the report that it was "reasoned". This thread, unfortunately like a lot of threads these days on PPRune, has turned into a waste of bandwidth with so called experts saying you do not need to follow SOP's etc etc. LUCK played a HUGE part in this INCIDENT not becoming an ACCIDENT with lives being lost. The person in question obviously did NOT have huge experience if he was confused by some minor "atmospheric phenomena ".
You pin heads that cannot differentiate between a reasoned decision based upon the circumstances extant and some silly argument about SOP's, Seniority, Rank, and who is the damn Boss....just need to wake up and smell the coffee.
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Iceman, I agree.
Checkerboard, how are you going to estimate that? With energy increasing exponentially and brake performance staying linear while moving at 140kts? How many aborts have you done to have a box full of experience to draw from? If you`ve flown for 20 years statistically you had 2. Probably on different types and certainly with variing environmental factors (temp, weight, surface,...).
Now maybe you did more than 2, maybe you are a 20.000h test pilot.
But that FO had some 2000h under his belt, that comes to 3 years of flying and, statistically, zero aborts. Maybe he even got 1500h of his experience on some light twin or so, that would hint towards this descision.
So maybe you estimate your takeoff performance, your fuel required, your dutytimes, wether that engine is still ok...
I make certain. "Maybe"s or guesses are not what I run the operation of an airliner under.
And I do maintain that aborting after V1, even if necessary very rarely, puts you in the grey area where you are only guessing. It might work out and it might not, but a fortunate outcome does not prove your ability to estimate the outcome, it proves that you got lucky.
Nic
Checkerboard, how are you going to estimate that? With energy increasing exponentially and brake performance staying linear while moving at 140kts? How many aborts have you done to have a box full of experience to draw from? If you`ve flown for 20 years statistically you had 2. Probably on different types and certainly with variing environmental factors (temp, weight, surface,...).
Now maybe you did more than 2, maybe you are a 20.000h test pilot.
But that FO had some 2000h under his belt, that comes to 3 years of flying and, statistically, zero aborts. Maybe he even got 1500h of his experience on some light twin or so, that would hint towards this descision.
So maybe you estimate your takeoff performance, your fuel required, your dutytimes, wether that engine is still ok...
I make certain. "Maybe"s or guesses are not what I run the operation of an airliner under.
And I do maintain that aborting after V1, even if necessary very rarely, puts you in the grey area where you are only guessing. It might work out and it might not, but a fortunate outcome does not prove your ability to estimate the outcome, it proves that you got lucky.
Nic
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Whatever happened to the concept of "Thinking" while you are set there in the front end?
You are going to tell me that thinking: "Oooh, I`ve got an airspeed anomaly! Oh my god, whattodo, whattodo? I am past V1, past Vr, so I better get that nosegear back onto the RWY and pull 'em to idle and let the old man handle the rest. My profound judgement assures we will stop before the concrete ends and desaster starts..."
is better than thinking: "Oooh, I`ve got an airspeed anomaly! Oh my god, whattodo, whattodo? I am past V1, past Vr, so I better pitch up to my usual 15 deg, get some air under my keel and then consult with my colleague on how to solve the problem!"
You decide.
Nic
Admiral346, you are develoing a good point. However, in this incident the airspeed anomaly was just one of the concluding factors in the pilot’s assessment, which resulted in the belief that the aircraft was unsafe to fly.
The puzzle is what other factors or strength of belief contributed to this assessment. Was it previous knowledge, erroneous belief - either from training or industry wide information, misperceived cues with rational evaluation, or just irrational thoughts (subconscious influences).
I have investigated similar incidents and in the majority of cases the person cannot fully explain the rationale used, or weigh the effect of influencing factors. In most accidents there are many factors and thoughts which come together at a critical time.
One individual in very similar circumstances (RTO > V1) reported that the decision would have been different on a shorter runway, but neither of us could determine why the thinking would have changed, suggesting that the original decision was not rational. The pilot had not experienced any similar situation in his career, which also implied that the issues had not been thought about beforehand.
These are problems of tactical decision making; this can invoke human weaknesses which can result in error.
Thus there is an important need to think about situations beforehand; it must be part of the strategy – strategic thinking, strategic decision making (without prejudging situations).
Thinking about a range of issues generates knowledge, which might eliminate some confusion from time-constrained assessments. Also, having a ‘Go’ mindset above V1 provides a greater safety bias to our thoughts than might an on-the-spot evaluation.
The puzzle is what other factors or strength of belief contributed to this assessment. Was it previous knowledge, erroneous belief - either from training or industry wide information, misperceived cues with rational evaluation, or just irrational thoughts (subconscious influences).
I have investigated similar incidents and in the majority of cases the person cannot fully explain the rationale used, or weigh the effect of influencing factors. In most accidents there are many factors and thoughts which come together at a critical time.
One individual in very similar circumstances (RTO > V1) reported that the decision would have been different on a shorter runway, but neither of us could determine why the thinking would have changed, suggesting that the original decision was not rational. The pilot had not experienced any similar situation in his career, which also implied that the issues had not been thought about beforehand.
These are problems of tactical decision making; this can invoke human weaknesses which can result in error.
Thus there is an important need to think about situations beforehand; it must be part of the strategy – strategic thinking, strategic decision making (without prejudging situations).
Thinking about a range of issues generates knowledge, which might eliminate some confusion from time-constrained assessments. Also, having a ‘Go’ mindset above V1 provides a greater safety bias to our thoughts than might an on-the-spot evaluation.
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You are making the common mistake of assuming that V1 is relevant.
V1 is simply a variant of Vmc, the speed at which it is safe to takeoff following a failure of one engine assuming no other damage.
V1 tells you nothing about the available stopping distance, nor does it have any relevance whatsoever to any failure other than the failure of one engine.
Everyone trains in the simulator for an engine failure on takeoff until the response is (hopefully) instinctive but once again this training is irrellevant and indeed can be misleading in the event of some other failure.
Other failures can, and do, occur.
The prudent pilot maintains a running mental picture of the remaining stopping distance until the aircraft is safely airbourne because control problems can occur which are not obvious until the wheels leave the ground.
V1 is simply a variant of Vmc, the speed at which it is safe to takeoff following a failure of one engine assuming no other damage.
V1 tells you nothing about the available stopping distance, nor does it have any relevance whatsoever to any failure other than the failure of one engine.
Everyone trains in the simulator for an engine failure on takeoff until the response is (hopefully) instinctive but once again this training is irrellevant and indeed can be misleading in the event of some other failure.
Other failures can, and do, occur.
The prudent pilot maintains a running mental picture of the remaining stopping distance until the aircraft is safely airbourne because control problems can occur which are not obvious until the wheels leave the ground.
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Greek, I agree with you as to what V1 is really for. However all the sims (Airplane) the Capt would brief what he would stop for and after V1 we were going flying. I know there is know way to train for every eventuality however we never did train for 2 engine failures on the 8 after V1. We never had a catastrophic fire after v1 (as the Concord did). I think we are so ingrained in the same old training we do not think outside the box anymore.
Originally Posted by Admiral346
Aborting after V1 means you have completeley left the calculated, controlled operation of an aircraft and the outcome is depending on luck.
Often it is 3m.
Sometimes it is 900m (even when using a flex/assumed temp).
Obviously this is due to the limiting segment, but knowing this data can help the Captain make an informed decision if the whole plot suddenly enters new and untrained territory. A decision to stop after V1 might be based on these numbers, and not just a guess and subsequent luck.
* not FR, and I don't know whether FR crews have this data. And the thought of the FO initiating a surprise stop after V1 gives me the willies, either way.
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In this case, no-one will ever know whether the pitot tube (dented out of limits, according to the 38 page report) was about to condemn this flight to become a smoking pile of junkyard scrap.
Let's out big sigh......
Pininstauld (and others):-
As I've already said earlier on this forum, Selecting an appropriate pitch angle and power setting, even without any airspeed indications at all, will keep an airplane flying at at any stage of flight.
Hardly a matter of converting the aircraft to "a smoking pile of scrapyard junk"
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Exactly what is that well known problem with "Flemish" speaking pilots? Flemish isn't a language by the way.
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100%:
We use a similar tool on our laptop, and going out of my homebase with 4000m RWYs there`s always a lot of margin shown, even in winter.
But this does not mean I can safely abort above V1. At 140kts your aircraft runs some 75m per second. If it is not an A343 it will gain around 5 to 10 kts per second. So the next second it might be running 85 meters. So with an average time of becoming aware of a problem, assesing it, and taking action of some 5 seconds how far have you travelled down the RWY? How much is left? Consider that you are now at much higher energy than the calculated V1 abort.
Don't tell me you can calculate that, not even give a good guess, especially not while in the cockpit and not at a desk with a calculator and all the time you need.
I am sorry, but V1 tells me that if an abort is executed at precisely that speed and I have good brakes and tires I will get the machine stopped on the pavement.
The closer I get to V1 the less likely I will abort for some tire problem as my braking might not be what went into calculation. I am already guessing here as the factors involved are not known.
I recommend reading this report:
http://www.nlr-atsi.nl/eCache/ATS/15/694.pdf
Title "REJECTING A TAKEOFF AFTER V1…WHY DOES IT (STILL)
HAPPEN?"
It really changed my view on takeoff aborts, and on how little margin I am willing to accept, and when do I call "GO".
Nic
Not exactly. Whenever we* prepare and enter our performance data, the software tells us how much runway will be left after an abort at V1.
Often it is 3m.
Sometimes it is 900m (even when using a flex/assumed temp).
Obviously this is due to the limiting segment, but knowing this data can help the Captain make an informed decision if the whole plot suddenly enters new and untrained territory. A decision to stop after V1 might be based on these numbers, and not just a guess and subsequent luck.
Often it is 3m.
Sometimes it is 900m (even when using a flex/assumed temp).
Obviously this is due to the limiting segment, but knowing this data can help the Captain make an informed decision if the whole plot suddenly enters new and untrained territory. A decision to stop after V1 might be based on these numbers, and not just a guess and subsequent luck.
But this does not mean I can safely abort above V1. At 140kts your aircraft runs some 75m per second. If it is not an A343 it will gain around 5 to 10 kts per second. So the next second it might be running 85 meters. So with an average time of becoming aware of a problem, assesing it, and taking action of some 5 seconds how far have you travelled down the RWY? How much is left? Consider that you are now at much higher energy than the calculated V1 abort.
Don't tell me you can calculate that, not even give a good guess, especially not while in the cockpit and not at a desk with a calculator and all the time you need.
V1 tells you nothing about the available stopping distance, nor does it have any relevance whatsoever to any failure other than the failure of one engine.
The closer I get to V1 the less likely I will abort for some tire problem as my braking might not be what went into calculation. I am already guessing here as the factors involved are not known.
I recommend reading this report:
http://www.nlr-atsi.nl/eCache/ATS/15/694.pdf
Title "REJECTING A TAKEOFF AFTER V1…WHY DOES IT (STILL)
HAPPEN?"
It really changed my view on takeoff aborts, and on how little margin I am willing to accept, and when do I call "GO".
Nic
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I recommend reading this report:
http://www.nlr-atsi.nl/eCache/ATS/15/694.pdf
Title "REJECTING A TAKEOFF AFTER V1…WHY DOES IT (STILL)
http://www.nlr-atsi.nl/eCache/ATS/15/694.pdf
Title "REJECTING A TAKEOFF AFTER V1…WHY DOES IT (STILL)
Firstly the report only considers 'accidents' and 'serious incidents' which means that it does not include cases where the aircraft stopped safely on the runway with no damage or injuries. It is probably safe to assume that this implies that the decision to reject was incorrect but safe in such cases.
In the cases considered between 1994 and 2008 31.9% of the aborts were justified, 44.4% not, and 23.6% unknown. This does not seem unreasonable given natural human survival instinct and the need for a very rapid decision.
The critical problem here is the available decision time. Slow decisions are very dangerous due to rising speed and rapidly reducing space. Given that almost a third of the aborts were justified we must assume that a high proportion of these would have been fatal or highly dangerous if not aborted.
The important question that the report does not address is simple :-
We know that any delay in deciding to abort is dangerous.
Is it safer to make a snap decision to abort or to go, given the strong possibility that in almost a third of cases the aircraft may be unflyable.
How many fatalities have resulted from avoidable 'go' decisions compared to those from abort overruns and how many of the overrun fatalities are attributable to slow decisions and action.