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Would you abort after V1?

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Would you abort after V1?

Old 20th May 2008, 20:12
  #181 (permalink)  
 
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PA,

Some light jets can still climb like a ruptured duck on one during second segment on up, or a single engine missed approach.

I still remember my right seat checkride in the Sabreliner 60, coming from older radial four engine equipment. I was very impressed with the performance. When I was given a missed approach off an ILS on one engine, I began pulling the power back on the good engine. The examiner had a fit and asked why. I had too much performance and only had three thousand feet to climb to the missed approach hold. It's a matter of perspective somewhat, there. He thought we had hardly any performance left, I thought we had too much.

A 20 series Learjet will hold 6,000 fpm in the climb easily enough, and the initial climb can exceed 12,000 fpm when light. It can hold several thousand fpm up through about FL290 or so. The cost, of course, is that you can actually see the fuel gauge move...

---(that's on two engines, not one)
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Old 20th May 2008, 20:24
  #182 (permalink)  
 
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SNS3Guppy

I think that the LEAR 20 series are not turbojets they're space rockets---or wannabe F4's---although I can tell you [as you know] they have taught some of the bigger jets how to really get upset though...I'll forever miss that baby though
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Old 20th May 2008, 20:50
  #183 (permalink)  
 
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Question.....if balanced field for the day is 5000ft on a ten thousand ft runway...could you calculate max V1 to just make the stopway on a rejected take off on that runway?
Did anyone say you can't? As long as the V1 is below Vmbe and V1stop and Vr.
But then if you want to abort after Vr... that's a different story... I'd do it if I can't even reach V2 and decelerating if I still got the fence in front of me. If the fence is behind... well, pray...

Multiple engine failure etc? Well, if you are sure you cannot attain safe flight (for a safe return), just stop and pray you won't hit the petrol station on the other side of the fence (even if there is an extra 5000ft clearway after the 5000ft runway remaining).

The later shows that the pilot has more discretion because he has more time, more options...To purposely take away those options by choosing a shorter runway, using Flex, adding weight...adds risk...I didn't say dangerous, I said risk...
Flex is dangerous? *bangs head on table*
Let's put it this way, estimated value of risk from FLX / estimated value of savings from FLX. As long as your take off performance is legal, and your climb numbers are OK, if that equation yields an answer of <1, then FLEX is the way. If >1, well, the insurers will surely have a word with management.

It won't add another line the checklist...

PK-KAR
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Old 20th May 2008, 20:55
  #184 (permalink)  
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I understand the argument.. I hear 'legal' numbers and 'ok' climb...so Fly it to the fence to save some money on overhauls, even if you have to push balanced field into the overrun?
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Old 20th May 2008, 21:03
  #185 (permalink)  
 
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I think that the LEAR 20 series are not turbojets they're space rockets---or wannabe F4's---although I can tell you [as you know] they have taught some of the bigger jets how to really get upset though...I'll forever miss that baby though
The Lear 24 is the only aircraft I flew in which I declared minimum fuel while taxiing .

Stuck in the lineup at Phoenix on a very hot summer day, 45 minutes into the wait, the reserve was gone and the air conditioning was non-existant. I asked the controller how long, he gave a mystical response about time and space and birthdays to come, and we declared minimum fuel. He asked if we were kidding, and we told him, no, we needed to taxi clear and go back to the FBO for fuel.

One of my reserve fuel tanks today holds nearly as much as the whole airplane did then...but it still kills us to hold short today for very long when we only allot 3,000 gallons for the taxi...some things never change.

I think that translates somewhat to this thread; it's different scales for different sizes of airplane, but the principles remain true...including those for V1.

Several posters here have thrown out some outlandish concepts regarding locked flight controls and so forth, and then asked the utterly ridiculous question as to whether one will continue the flight or not. Clearly when flight is not at all possible one will not...that shouldn't even need to be dignified by discussion...but where the airplane will fly and is able, there's just no good reasont to stay on the ground. Even in a Lear. With a drogue chute...

Of course, in a citation, where the biggest threat is experiencing bird strikes from behind...
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Old 20th May 2008, 21:08
  #186 (permalink)  
 
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>Also explain to me what are the basics of the segmented takeoff profile?-because a 4000'/min segmented climb oei at V2 wow<

As this thread has taken on a new lease of life and everyone appears to be changing sides I would like to know which Citation will climb at 4000 feet per minute at V2 unless it has literally no fuel and no pax ?

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Old 20th May 2008, 21:12
  #187 (permalink)  
 
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"if you got a flap asymmetry warning, an un-commanded slat retraction, a trim runaway, an obvious control jam or hard-over, a double engine flame out, (if you only had two for the less astute among you) after V1 you would not even consider aborting the take off because you had said so???"

If the space shuttle, operating on UHF Freq, lands 2000 feet in fron of you, but you have an engine over temp at Vr, are you still going to attempt to stop? What if it is a UFO?

Isn't this getting a bit esoteric? If you have a loss of both engine, it will be a very short flight, whether one rotates or not. All the rest of your examples are just about the same, the a/c isn't going to fly, well again, at least not very far. However, I am at loss to any of your examples ever having happened, doesn't mean they can't, but it is highly unlikely, bordering on impossible. I mean really, dual engine flameout on the runway???
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Old 20th May 2008, 21:12
  #188 (permalink)  
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No one said anything about v2 or single engine...Citation Vs, Ultras and Encores can do 4000 ft/m...for while
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Old 20th May 2008, 21:23
  #189 (permalink)  
 
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Dieasel 8

Probably the most sensible thing said. Dual flameout forget V1 VR and the rest because you are not going anywhere fast.

Control failure the same. Massive engine fire or airframe fire and I am taking my chances earthwise, If need be at the end of the runway I will do a formula 1 turn up a taxiway :-) to extend my ground run.

The rest sort it out in the air.

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Old 20th May 2008, 21:33
  #190 (permalink)  
 
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I think that the LEAR 20 series are not turbojets they're space rockets---or wannabe F4's
Isn't it an oversized fighter with fighter wings and a plush cabin instead of a bomb bay?

so Fly it to the fence to save some money on overhauls, even if you have to push balanced field into the overrun?
if the company wants to go to the overrun as part of the stop, so be it, I'd probably just move companies. Flex it as far as the stop goes to just short of the overrun and the climb numbers are OK is fine by me. If the company wants to loose the tyres being sunk in a soft overrun, it's their choice. The insurers will have a nice chat with the management.

But when that's the V1 chosen, definitely no abort past V1 unless the conditions dictate it's better to stop and pray I make it before the petrol station on the other side of the fence.

Basically aborting past V1 as per the majority of your posts and flex is the same in that you're making the decision with less stopping distance available.

If you've been preaching you'd stop past V1, I don't see why you'd look down at flex t/o... unless, you want to abort past V1 so much that you'd never flex t/o because you know U'd be in deep doo-doo whenever you make a stop or go decision past V1high...

Have a read at that link again, with V1low, feel free to be stop minded, with V1high, be go minded. Your choice, your life... we won't laugh. If your stop minded with V1high (which I'm sure U're not), then we won't laugh, we'd just shake our heads.

If you're nitpicking as to which is safer, and your workplace has a V1 policy you're not comfortable with, just move somewhere else that can give you the comfort (dunno and dun really care which companies go for V1bal, V1low or V1high, take yer pick), and accept the fact that some others have a different V1 policy to what you want that's still legal (and safe ..
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Old 20th May 2008, 21:52
  #191 (permalink)  

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Several posters here have thrown out some outlandish concepts regarding locked flight controls and so forth, and then asked the utterly ridiculous question as to whether one will continue the flight or not. Clearly when flight is not at all possible one will not...that shouldn't even need to be dignified by discussion...but where the airplane will fly and is able, there's just no good reasont to stay on the ground. Even in a Lear. With a drogue chute...
With great respect to the crew of AA191, I bet they were pretty unimpressed with the outlandish event which led to them losing No 1...after all, initially, the indications probably just looked like any other engine failure...

Diesel8,

Un-commanded slat retraction - 1979, AA191

Obvious control jam, hard-over - 2001, LH A320 Cross-wired Sidestick

Double engine failure - 2001, S360 departure from EDI

Say again, what you think is impossible?

The point is, that there may come a time, when near, at, or above V1 you might be called upon to make a decision about whether or not your aircraft is able to fly...

...there's just no good reason to stay on the ground...
I figure the fact I don't have feathers is a pretty good reason...

The problem is, that regardless of what decision you make at that point, if the outcome is successful its self-justifying...but whether or not there was a better outcome, will always be debatable. Plus, you'd be a brave pilot to admit as much, esepcially if there were fatalaties...

When operating at the edge of the envelope, I prefer not to extrapolate based on the norm...that is bad practise in any mathematician's book...

Hoping it never happens to me....

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Old 20th May 2008, 22:18
  #192 (permalink)  
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SR71

+1....well said / There are alot of pilots in here living a world where things don't go wrong, just pull the levers before V1, push them up after. I take solace in the fact that maybe these posters are retired, don't fly, unemployed, or at the least FOs where they are not allowed to make a decision...
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Old 20th May 2008, 23:21
  #193 (permalink)  
 
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+1....well said / There are a lot of pilots in here living a world where things don't go wrong, just pull the levers before V1, push them up after. I take solace in the fact that maybe these posters are retired, don't fly, unemployed, or at the least FOs where they are not allowed to make a decision...
Of course you and most others here have a damn good idea of how to make rational decisions of whether to go or not.

The problem is the time base that you are constrained to rationlize such a decision and so little training or experience in creating rational thoughts outside the box in this time period.

So I'll rather trust my life with pilots that think inside the box (of their training), for that has been proven statistically safe.
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Old 20th May 2008, 23:34
  #194 (permalink)  
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Your absolutely right..we can monday morning quarterback for hours all these scenarios when in real life the decisions have to be made quck..

But I will throw this at you...if they can't make the right decision in front of thier computer, how will they do it at 120kts having just clipped a fuel truck post v1?

Last edited by ssg; 20th May 2008 at 23:45.
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Old 20th May 2008, 23:55
  #195 (permalink)  
 
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Er?!

With a thread this long I looked at the first page and the last.

There really is no point in debating this apart from certain acedemic aspects to the process which can be interesting since it throws up a couple of curved balls.

There is no data in the FM for braking distances beyond V1. And for good reason. If you decided to flip that particular coin then you become your own test pilot and I'm not too sure the rest of the crew will thank you for it. Even if the decision to remain on terra firma after V1 is taken and gotten away with due to extreme circumstances the post flight euphoria will diminish when the investigation reveals that you were happy to keep the problem earth bound. No protection in a court of law for that. Then you are on your own; a lonely place to be.


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Old 21st May 2008, 00:05
  #196 (permalink)  
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I was wondering when this would come up..

Gee Whiz can't anyone in here look at some pavement and get a decent idea if they have enough to stop? We do it every day in cars...what's the diff?
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Old 21st May 2008, 00:18
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"Un-commanded slat retraction - 1979, AA191

Obvious control jam, hard-over - 2001, LH A320 Cross-wired Sidestick

Double engine failure - 2001, S360 departure from EDI"

And in which ones of those were the a/c still on the ground past V1 with the ability to safely stop?

Cannot speculate on 191, although the uncommanded slat retraction was a we all know, due to the fact that the engine seperated from the a/c. Had it just been an engine failure, little doubt they would have survived. Had they stopped, for a "mere" engine failure past V1, it is not known, that the a/c would have stopped on the remaining rwy, it may well have plowed into houses, broken up and burst into flames. The report would have certainly faulted the crew for that, afte all, that would not be SOP nor the manufacturers recommendation.

In this article, you will notice, that the engine loss/slat retraction was deemed surviveable, after having re run the scenario in the sim, however, certainly we cannot blame the pilots on AA191, rest their souls, for the outcome. http://en.wikipedia.org/wiki/America...nes_Flight_191

LH was not a control jam, the controls moved freely, the CA sidestick was miswired, the F/O stick was working properly. They found out when the a/c was airborne, that is when the CA used roll input. He would not have been aware prior to V1, that is unless they had noticed the anomaly during the control check at taxi. Of course, in that case they never would have taken off. Certainly you are not advocating the LH pilots should have tried to land on the same rwy after having been airborne, with a stick malfunction to boot. That surely would have led to an overrun or worse, a crash. Interestingly enough, Airbus FBW do have a procedure for frozen or malfunctioning sidestick and no one was harmed in the incident.

The SD360 was at 1200 feet when they experienced trouble, a couple of minutes removed from V1, is that example even pertinent? Why not mention the SAS MD-80 out of Stockholm, they had dual engine failure a minute or two removed from V1. Maybe they Gimli glider should have aborted at V1 plus 20, then they never would have suffered dual engine failure in cruise.

None of your examples appear to offer much that is relevant, nor anything that supports the argument of stopping past V1. In two of the cases, the a/c was already airborne, with no indications of malfunctions prior to and in the case of AA, the crew had no indications of anything other than an engine failure. The AA crew at the time, made the right choice based upon what hey knew, since they couldn't possible have known the engine was torn off and that the slats would retract.

Statistic show, that the safest course of action, past V1, is to continue the takeoff. It has been proven time and time again. It is the recommendation of all FAR 25 manufacturers, all airlines, all training academies etc, etc.

Is it possible to come up with situations where it would not be the prudent course of action, yes it is. Dual engine failure on the ground, an aircraft that will not rotate, loss of an entire wing, etc. However, do any of those happen on such a recurrent basis, that it should be considered normal, besides, under such scenarios, is there even a choice?

Last edited by Diesel8; 21st May 2008 at 00:35.
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Old 21st May 2008, 00:32
  #198 (permalink)  
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Is there any emergency when taking off that you would consider normal.?

Funny, the latest accidents I see are blown tires, plane doesn't accelerate, someone horses it off the runway then crashes...

gotta go, gotta go....
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Old 21st May 2008, 00:37
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True Ssg there's been tons of bloodshed in aviation to make it safe--and yet we insist on recreating the original TO and LDG accidents--for historical and educational purposes I suspect
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Old 21st May 2008, 00:43
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"Is there any emergency when taking off that you would consider normal.?"

Nope, but then again, losing an engine, considering the excellent training we get now a days, could probably be considered more of a non routine. A blown tire shouldn't cause much grief in the front office either. Having been through both, cannot say they were much of an event.

Here is a great example of some well executed airmanship:

http://www.youtube.com/watch?v=uYNpB-8_BSo

Should they have tried to stop?

This one was an RTO at supposedly 12kts above V1:

http://aviation-safety.net/database/...?id=20060607-0

http://www.youtube.com/watch?v=wj8UP...eature=related

Last edited by Diesel8; 21st May 2008 at 01:04.
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