Rejecting A Takeoff After V1…why Does It (still) Happen?

[Mad (Flt) Scientist]

Originally Posted by johns7022

Galaxy - 76000 Crews performed RTOs, with a 99.99% success rate of not hurting the plane or passengers.

Translated: That's 76000 crews that think your a nut Galaxy for telling them they should have flown the problem up into the air.

Absolute garbage.

That's 76000 RTOs, the overwhelming majority of which were excuted from speeds well below anything being proposed by you. If you are going to discuss the risk inherent in a HIGH SPEED RTO you have to base the discussion on what happens when you actually do a high speed RTO - not what happens when the TOCW fires at brakes release and the "RTO" is from about 15 knots!

I'm going to try to explain the error in your "analysis" by making up some numbers, but only because I can't be bothered tracking down the actual numbers.

In the last 30 years - 1980-2010 - there have been 10 million aircraft takeoffs from the state of Florida. Of these 10 have resulted in an accident resulting in either loss of life, loss of the aircraft or both. (the actual numbers are made up - the ratio - one accident per million flights - is about right for commercial transportation.). 135 of those flights have been on the Space Shuttle.

You are attempting to argue that because a very large number of events have had "safe" outcomes, all of those events are equally safe. The statistics show that the hazard of an RTO is very much a function of the rejection speed. To ignore that is akin to claiming that the risk of the next shuttle launch resulting in disaster is approximately one in a million - ignoring all the evidence specific to the events in question, which suggest its historically more like 1 in 100.

I do risk analysis for a living, and risk analysis specific to the hazards associated with aircraft operations at that. If I were to argue, based on 76000 RTOs covering all conditions, that high speed RTOs were also equally "safe" (ignoring all the data to the contrary) and that we could happily certify our products on such a basis - well, I wouldn't be doing what I do for a living much longer.

[de facto]

When i flew in a FAR 135 carrier in the USA(single pilot), the common joke was that Citations should be renamed 'SLOWtations'
Maybe there lies the problem..a slow aircraft,

[galaxy flyer]

Johns7022

And 74,480, that is those rejections below 120 knots, I would have almost invariably agreed with--that speed in airliner types is high, but justified, if below V1 in the event. The remaining 1520 are, at least, questionable and in my operation would be investigated by the Standards and Safety pilots. Circumstances, training, and recommendations would be made. I know, on both civil and military positions, I have done just that for cases like this.

WRT, MfS's comments, you might spend time studying risk analysis and statistics, specifically Bayes' Theorm.

My appreciation, MfS

defacto, my 2,500 hours in it leads me to say, it is a plane for those who have thought a lot about jet piloting, but haven't the courage to try it.

GF

[johns7022]

Safetypee....your words are water to a dying man in the desert...

Mad - Based on the evidence, I can run up and down the runway, holding the nose down till well after 120kts, and have a better chance of bedding Pamela Anderson then putting more then a little mud on the tires at the end.

Cling to brake failures and RTOs being deadly and anything after V1 is 'danger danger Will Robinson' but the statistics don't bear it out.

The only thing that bears out is that if the crews, aborting at whatever speed they abort, had more runway...they would not have blown the tires, and put the mud into the gear..

You want to reduce RTO issues...stop assumed thrust / derated departures...give the crews more runway to work with...

[galaxy flyer]

The statistics say nothing of the sort, they show that RTOs at high speeds, especially beyond V1, are at least, 100 times more hazardous than those at low speeds. That is not the same as saying here is NO hazard at low speeds. Try a reject at V1 in a Citation at Newport, RI (2,990' and I've been there in one) and you will go off the end. Just like you would rejecting 10 knots past V1 departing KDOV at gross weight with a rotate increase speeds. That's overspeed V2 for you Airbus types.

[galaxy flyer]

Did you go off a runway on a flex power take-off and get the sack? As things stand right now, what airlines do have ZERO effect on you, so why the horror at them. Especially since they are, in fact, safer.

GF

[john_tullamarine]

We appear to be getting to the going around in circles stage. I'll leave it go for the time being but if we don't see some further development, it might be better to retire the thread ?

[johns7022]

So out of 76000 RTOs, 2% initiated at above 120kts...well past V1...let's stick with those..

2% x 76000 Total RTOs = 1520 High Speed RTOs

How many accidents? 74 = Less then one percent...or .05 percent.

So 99.95% of the High Speed RTOs resulted in No banged up Planes, and No loss of life..

And if we want to play with the numbers....let's talk about the .05 percent....how many of those were off shore...guys that couldn't run the numbers, pay to fly, new guys, crappy runways, junk equipment....????

And if that .05 percent had miles of runway ahead of them...do you think they would have flipped the planes over going straight forward? Do you think the plane explodes when the tires hit 130 kts? Do you think maybe they ran out of runway?
How many were over gross? How many flying Derate?

[SNS3Guppy]

Guppy.

Pick any V1 for the day.... add 5kts faster, 5% faster, ect....isn't going to cause a brake failure on an RTO.

Irrelevant.

I use a 10,000' runway, and see a stop margin (that's what's remaining after rejecting the takeoff at V1, by the way) of several hundred feet...assuming everything goes well, assuming the airplane does what it's projected to do, assuming that it can match the performance that the test airplane had on a perfect day with a test pilot at the controls, with new brakes, yada, yada, yada.

Assuming that the takeoff is rejected at or before V1. After V1? Those piddly few feet of stop margin are gone in a flash, and the stopping distance is considerably larger.

One is MUCH, MUCH safer going airborne, and coming back to land with a plan, with a full, vacant runway ahead, and with rescue services (as required) ready and briefed.

High-speed rejected takeoffs (after V1) tend to result in aircraft damage, loss of control, and put the airplane in exactly the wrong place for coming to a stop: at the end of the takeoff roll.

V1 is the point at which the decision time is over. One is now going flying. Unless something utterly catastrophic occurs which entirely prevents the airplane from flying, then one is far safer to go airborne, and sort it out on the way back to the full length of the runway.

Apparently everyone understands this but you. Then again, we all know why.

[Mad (Flt) Scientist]

Originally Posted by johns7022

So out of 76000 RTOs, 2% initiated at above 120kts...well past V1...let's stick with those..

2% x 76000 Total RTOs = 1520 High Speed RTOs

How many accidents? 74 = Less then one percent...or .05 percent.

Well, in fact, 74 out of 1520 is just under FIVE PERCENT. 1 in 20. Do you think a 1 in 20 risk of an accident/incident is a good basis for decision making?

Even 1 in 2000 - your erroneous value - is an unacceptable risk given that the expected/target accident rate is 1 per million. Anything which will cause a perceptible adverse change to that 1 in a million rate is a bad thing.

I'm going to go back to the 'Russian Roulette' analogy:

If I have a confirmed empty revolver, checked by myself and a trusted friend, then I can play Russian Roulette 'safely'. There remains the risk that my friend is secretly a psychopath, but on the whole it's safe. That's rejection before v1. Unless something exceptional occurs, it should be safe.

If I have a revolver picked randomly and handed to me by a stranger, to place it to my temple and pull the trigger is foolhardy, unless I am coerced to do so. That's rejection above V1 when I don't know what my margins are. Maybe all the chambers are empty and I'll get away with it. But maybe not. (Coercion = 'plane will not fly' by the way)

Even if I 'know' there is only one bullet in the chamber - analagous to understanding some of the margins for RTO above V1 - it's still a significantly elevanted risk. The risk of not playing/not going flying has to be very high for me to take the chance.

[A37575]

High-speed rejected takeoffs (after V1) tend to result in aircraft damage, loss of control, and put the airplane in exactly the wrong place for coming to a stop: at the end of the takeoff roll.

Never a truer word. A couple of short stories that might interest readers. During type rating training on the 737-200 simulator with brand new 200 hour graduates, we were practicing rejected take off procedure on a performance limiting runway. In other words if everything went as planned from an flame-out about 10 knots below V1, the student would stop within 100 metres or so before the end. We must have conducted ten of these within 15 minutes just to get the right sequence of actions. Both students were lightning quick on the actions - after all there was no stress because it was a training session; not testing.

In the majority of the rejected take off's, one student would consistently go off the end of the runway by 100 metres or so. Yet his actions were fast and accurate same as the other chap who pulled up OK.

From my position on the jump seat, by chance I turned around to look at the instructor panel screen as the student who was over-running, accelerated down the runway through 70 knots or so. I suddenly noticed that the indicated brake hydraulic pressure at the rudder pedals was not zero as it should have been, but oscillating rapidly between zero and around 500 psi during the length of the take of roll. This indicated the pilot must have been inadvertently riding the brake pedals on the roll. In the darkness of the simulator it was not possible to see exactly where his toes were on the rudder pedals.

The slower acceleration to V1 nullified the planned decision speed to the extent that, even the 10 knots below V1 chosen for the flameout, didn't make up for the slow acceleration.

This explained why he constantly over-ran after aborting - despite correct actions. When this was pointed out to him, he vehemently denied he had his feet up on the brakes during the take off. I think there was a culture aspect with loss of face which is why he refused to accept the obvious.

There had to be a way to convince him; since if he did this in real life, one day he was going to be in real trouble. Hot brakes for one.

So I asked his PNF (same country of birth) to sit at the instructor panel and observe for himself the brake pressure readings for each wheels. Sure enough, as the simulator went down the runway the little red indicators showing pressure at the brake pedals, bobbed up and down signifying partial brake being applied by the student. I then asked them to discuss this between themselves in their own language. Eventually there was an understanding nod of the head of the culprit when his mate explained what he had personally seen. After that he had no problems with the rejected take off's.

On a separate occasion in a real 737-200, the crew noticed the occasional flashing of the wing body overheat light while taxiing for take off. The runway was short (5400 ft) and the over-run area deadly with a cliff 20 yards from the end of the actual runway. The captain lined up and by now the wing body overheat light had extinguished. He briefed his F/O (who had just 500 hours total time) that below 80 knots he would abort for any Master Caution indication and after 80 knots he would keep on going except of course for anything serious like engine failure.

The 737 was runway limited that day and V1 was around 128 knots. At 10 knots below V1, the Master Caution light came on caused by illumination of the wing body overheat light. The captain instantly aborted, but in his haste initially forgot to select manual speed brake for a few seconds. With full braking and full reverse he was able to stop the 737 with the nose wheel right on the very end of the runway. It was a very close thing.

During the taxi back to the terminal, the F/O asked why had the captain aborted contrary to his briefing. The captain was honest and said he could not explain his change of decision but that it was an instantaneous reaction to the sudden appearance of a large amber Master caution light in front of him. One could easily criticise the captain's potentially disastrous action -especially his initial failure to extend the spoilers. But that is not the point of the story.

Both events of the dragging brakes student and the high speed abort just mentioned, are typical where incorrect pilot actions at a critical time on the take off roll and leading to a high speed abort, can increase the dangers of high speed aborts on a limiting length runway.

In the case of the brake dragging mistake, the V1 was compromised. Because of the inevitable momentary indecision that a crew will experience if something out of the ordinary happens when fast approaching V1, this writer is convinced that it is a much safer bet to keep on going than risk a stuffed-up late abort.

[mutt]

Does anyone here fly for an operator that includes an RPG Attack checklist in their QRH? I cannot find one in anywhere.

Actually we do

a very rare condition that only lives in the world people who run derated/assumed thrust or people who routinely fly jets, heavy, in and out of short runways....

Not rare at all, even on a 10,000 ft runway with no Derate/Flex, we routinely operate 747's that are limited by the 115% all engine capabilities. When you also consider that they have steel brakes, there is NO WAY that they are stopping on the runway if they consider V1 to be a DECISION SPEED rather than an ACTION SPEED, if they overrun one of our least favorite runways, the drainage ditch will rapidly remove the undercarriage.

Your argument may be valid on light jets operating on long runways, but in an airline environment, forget it.

As for the statistics regarding RTO's between 1960-1990, ask yourself what type of aircraft were operating in that era, what was the level of technology.

Finally, just admit that you are SSG come back to haunt us.......

Mutt

[johns7022]

I am sorry...your right Mad...5%......5% of the high speed RTOs had accidents..

Again how many were off shore, bad pilots, short runways, guys running derate, guys that couldn't brake, over gross, ect ect ect..

I'll take my chances, with a high speed RTO, just based on statistics alone in that I don't fly over gross, I can pull the levers back and step on the pedals...I do the flight planning and thus have a clue where my balanced field shakes out against runway length...

Do what you guys want...fly the emergency up in the air, because you painted yourselves into the corner with an assumed thrust departure...honestly I don't care...congress doesn't care, the public doesn't care, the FAA doesn't care...

All I can do is run my flight dept the right way..

Still here, I still remain.

[galaxy flyer]

Who was it that said, "some men trip over the truth, brush themselves off and continue as if nothing happened"

You can do as you please, just as long as it doesn't involve public transport, you are still wrong. As a Citation operator (contractor, perhaps?), your boss most likely doesn't have a clue as to the dangers to which you are exposing him. I doubt very much any training organization worthy of the name would teach these RTO procedures. You'll be on your own should the far end of the runway reaches out smites thee.

The scary part is, so far, you have not presented any clear, understandable means of verifying the aircraft's runway performance as to accelerate-stop distance, NONE, NADA, ZILCH. Please tell me you, at least, use some performance data to back up your guesses.

Do you hold off in retracting the gear until the runway is behind you so you can land it, if an engine should fail, too?

Mutt. Do you really have a checklist for that? I fly there often enough to be interested in knowing more.

GF

[johns7022]

What I love about these forums is some poster's position that they are speaking for a whole industry of professionals. Like they are part of the club....

I would love to fill up a room full of the 1500 crews that did a High Speed Rejected take off, and are here to talk about it...passengers are here to talk about it....and have some our very experienced and knowledgeable forum trolls tell these guys in person that under their specific circumstances, despite everyone walking away...there were wrong.

Some of you can only exist in a world where Darwinism doesn't exist, where credentials can't be checked, where anyone with a mouth and a keyboard has an opinion.

[galaxy flyer]

Only if we can bring in the families of the dead and get their opinions of captains that failed to follow procedures based on factual evidence and killed their kith and kin by rejecting the take-off at high speed. Did you read the CRJ overrun accident at KCRW? I suggest you do, I just briefed it to my pilots. The statistical evidence is clear--high speed aborts are hazardous and aborts past V1 are lethal.

What if they crowd of 1520 survivors were told that the failings of their crews exposed them to unwarranted danger, that they would have been, statistically, safer NOT stopping.

GF

[SinglePilotCaptain]

I think it's been said before...

A rolling aircraft does not guaranty a flying one.

With 5000 feet of balanced field, on a ten thousand foot runway....only an idiot takes an abnormal and turns it into an emergency by taking the problem up in the air.

I certainly won't apologize for my corporate brethren who have made mistakes as colossal and idiotic as the airline guys. I find it silly you hang on to some philosophy that your in some lifeboat with the other guys....they won't be there when the fire light comes on.

[galaxy flyer]

Oops, headin' for the rhubarb with SSG V2.1 aka SinglePilotCaptain......what idiocies in the future?

GF

[Brian Abraham]

Ya gotta admit GF he provides a comedy routine that Sienfeld would be envious of. Was wondering how long it would take before he started talking to himself, sure sign that ssg still ails.

[Lord Spandex Masher]

Johns

Lets say, hypothetically of course, that you were operating as part of a two man crew with...mmmm lets say Single Pilot Craptain in the RHS as handling pilot and you heard a bang, possibly a loss of oil on a PT6 (or something) at V1. SPC announces continue.

What do you do now?