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  • #76
    Originally posted by Evan View Post
    Like the Concorde. Oh no, wait, they continued didn't they...
    I don't know that the Concorde crash is a particularly good example of a case where a post-V1 abort would have been advisable, at least with the information the crew had. For one thing, the aircraft was flyable at liftoff, it was after that that things began to deteriorate and deteriorate rapidly. For another, they were thrown a multitude of failures in rapid succession and, finally, given the magnitude of the fire, it's not a certainty that they would have survived an abort. The only difference would have been they would have burned up on the runway rather than by that hotel.

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    • #77
      Originally posted by ATLcrew View Post
      I don't know that the Concorde crash is a particularly good example of a case where a post-V1 abort would have been advisable, at least with the information the crew had. For one thing, the aircraft was flyable at liftoff, it was after that that things began to deteriorate and deteriorate rapidly. For another, they were thrown a multitude of failures in rapid succession and, finally, given the magnitude of the fire, it's not a certainty that they would have survived an abort. The only difference would have been they would have burned up on the runway rather than by that hotel.
      I only used that as an example of how dangerous a fatally wounded aircraft is in the air. I dont thnk that crew could have known the extent of the damage and given the high takeoff speeds of the concorde an rto might have ended with similar results (but one less hotel on fire)

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      • #78
        Originally posted by Gabriel View Post
        Exactly, because whatever V1+X you define, the airplane that was reluctant to lift off at V1+X might happily lift off at V1+X+2kts.

        I'd say that the issue is not at what speed, but given what failure.
        If a wing is torn off, if more than engine fails, if the yoke doesn't move at all, etc... I'd say "abort".

        That is to say, if you have made a judgement that the airplane WILL NOT fly, abort. Otherwise, go. Yes, it's a full monty bet (either you survive unscratched or you die, nothing in between), but one that you have much more chances to win.

        Statistcally speaking, a high speed abort gives you more chances to survive than a keeping accelerating in an airplane that will not lift off. But will it not lift off? History shows that, most of the times, it will, and in that case your chances to survive are much grater than a high speed abort.

        Of course, that history doesn't apply to both engines failing or a wing left behind on the tarmac. So in those cases, abort at whatever speed you are.
        But what if you have no idea what the problem is? You are pulling back, the other yoke is following, airspeed and runway position indicate that you should be airborne, something is VERY wrong and you have a very confused situational awareness. It still MIGHT lift off but it might not be controllable or it might not and continuing to accelerate exponentially decreases the odds of survival. Shouldn't there be some guidelines here? Many RTO accidents (where major end of runway hazards are not present) do not involve major fatalities, just hull loss and minor evac injuries. Saving lives is the important thing here. Is it possible to set a limit over v1 where you should rto if you cant lift off? Yes, it might ret in more write offs but it might also save lives (and this is a rare scenario we are talking about). What about a v speed (say, vr + 20 or 30) for mandatory rto?

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        • #79
          NO. Full Stop. Period. End of.

          If you RTO above V1, you are doing it because you genuinely believe the aeroplane is unsafe or unable to fly, and you are making the assumption that hitting something at the end of the runway at a low/medium speed is better than hitting it at a higher speed. You're only doing it because you think you can't fly and get back on the ground. That principle applies regardless of if you are at V1 + 1 or V1 +50.

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          • #80
            Originally posted by Evan View Post
            But what if you have no idea what the problem is? You are pulling back, the other yoke is following, airspeed and runway position indicate that you should be airborne, something is VERY wrong and you have a very confused situational awareness. It still MIGHT lift off but it might not be controllable or it might not and continuing to accelerate exponentially decreases the odds of survival. Shouldn't there be some guidelines here? Many RTO accidents (where major end of runway hazards are not present) do not involve major fatalities, just hull loss and minor evac injuries. Saving lives is the important thing here. Is it possible to set a limit over v1 where you should rto if you cant lift off? Yes, it might ret in more write offs but it might also save lives (and this is a rare scenario we are talking about). What about a v speed (say, vr + 20 or 30) for mandatory rto?
            Thanks MCM.

            Evan, I've said it already (admitedly in not as clear fashion as MCM).
            If you don't know what it is, history shows that chances are that it WILL fly.
            Guarantee? Sure not. In either way. The guys in Teterboro were extremely lucky. They crossed a parking lot, a many-lanes highway, impacted a ground vehicle seriously injuring their occupants, and then crashed into a building. And they walked away!!!! Liteally WALKED. Had they impacted more / a larger vehicle, had they finished a little bit more inside the building, had the wall of the building beet a little bit tougher, had fuel tank suffered a serious rupture in any of all that... and they'd be barbacue.

            And STILL, the plane would have flown away had the pilot kept trying one second more.

            How many accidents do you know where the pilots continued an impossible take-off and the airplane failed to fly, there were fatalities as a result, and they would have survived had they aborted past V1?

            Let me tell you some examples that don't qualify:
            The MD-80s in Detroit and Madrid, the 727 I don't remember where ("say something for your wife in the CVR in case we crash"), the LAPA 737 in Buenos Aires, the 737 in the Potomac, the American DC-10 in O'Hare.

            --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
            --- Defend what you say with arguments, not by imposing your credentials ---

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            • #81
              Originally posted by MCM View Post
              NO. Full Stop. Period. End of.

              If you RTO above V1, you are doing it because you genuinely believe the aeroplane is unsafe or unable to fly, and you are making the assumption that hitting something at the end of the runway at a low/medium speed is better than hitting it at a higher speed. You're only doing it because you think you can't fly and get back on the ground. That principle applies regardless of if you are at V1 + 1 or V1 +50.
              Is that some sort of broadly-applicable, fundamental principle? We can't have that!
              Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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              • #82
                Originally posted by MCM View Post
                NO. Full Stop. Period. End of.

                If you RTO above V1, you are doing it because you genuinely believe the aeroplane is unsafe or unable to fly, and you are making the assumption that hitting something at the end of the runway at a low/medium speed is better than hitting it at a higher speed. You're only doing it because you think you can't fly and get back on the ground. That principle applies regardless of if you are at V1 + 1 or V1 +50.
                Well, yes, that is what I'm asking. Of course you don't RTO above V1 if the plane will fly and land again. But it it won't lift off, when do you give up and reject? At some point it is too late (I would venture that V1 +50 might be a bit beyond that line) to expect a survivable controlled crash beyond the runway. I think maybe there should be a calculated limit to how fast over V1 you can go without lifting off or rejecting. Not to save the plane, to save the passengers.

                The Boeing video even states that when the airworthiness of the aircraft is in doubt, it is acceptable to RTO after V1. It gives no guideline as to when to call it off though.

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                • #83
                  Originally posted by Gabriel View Post
                  the 727 I don't remember where ("say something for your wife in the CVR in case we crash")
                  This one (and they were discussing this one).
                  "I know that at times I can be a little over the top." -ITS

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                  • #84
                    Originally posted by Evan View Post
                    The Boeing video even states that when the airworthiness of the aircraft is in doubt, it is acceptable to RTO after V1.
                    Not exactly. What the Boeing video says is this:

                    Originally posted by Boeing video
                    Although a reject beyond V1 may be necessary, and it's fully within the emergency authority of the captain, it should not be attempted unless the ability of the airplane to fly is in serious doubt. It's normally best to continue the take-off and deal with the problem in the air.
                    Note:
                    "... it should NOT be attempted (unless...)". While the strict meaning of this can be considered the same than "it's acceptable", clearly the tone and intention is not the same.
                    "... unless the ability of the plane to fly...". This is absolutely different to "the airworthiness".
                    "... is in SERIOUS doubt". The stress on SERIOUS is in the voice of the narrator.

                    And don't forget the "... best to continue the take-off and deal with the problem in the air" part.

                    It gives no guideline as to when to call it off though.
                    Yes: When the ability of the plane to fly is in serious doubt.

                    Forget about the speed. The moment that you judge that the plane can't fly you abort no matter what speed. As long as you don't reach that judgement, if you are past V1 you go.

                    Worst than that: the manufacturer could be sued. Imagine a case like the accident in this thread with several deaths:

                    CVR:
                    FO/PF: I don't know why it won't rotate yet.
                    PIC/PM: I think that the plane can still take off, we need just a few more knots.
                    PIC: Oh, well. V3. Reject (mind recorder: "I don't agree with that, but that's the SOP). Let's try to make a survivable overrun.
                    FO: Oh, shit, we ain't stopping in time.
                    PIC. Watch that ditch. Brace!
                    [sound of impact]

                    And then the investigators find that there was a trim misconfig and that the plane would have been able to rotate and lift off had the pilot waited a couple more seconds.

                    The decision is and must be based on the PIC's judgement of the ability of the plane to fly. And to your dismay, it's a judgement call. No strict procedure can be written on what constitutes a "won't fly" judgement.

                    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                    --- Defend what you say with arguments, not by imposing your credentials ---

                    Comment


                    • #85
                      We wouldn't be having this discussion if this had been laid down...... http://www.faa.gov/news/fact_sheets/...m?newsId=12497
                      If it 'ain't broken........ Don't try to mend it !

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                      • #86
                        Originally posted by brianw999 View Post
                        We wouldn't be having this discussion if this had been laid down...... http://www.faa.gov/news/fact_sheets/...m?newsId=12497
                        Note that the EMAS is supposed to be installed where an RSA is not practicable. With the long paved overrun and then a long flat grassy area, this airport seems to have an RSA that meets or is very close to the standards.

                        --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                        --- Defend what you say with arguments, not by imposing your credentials ---

                        Comment


                        • #87
                          Originally posted by Gabriel View Post
                          Not exactly. What the Boeing video says is this:


                          Note:
                          "... it should NOT be attempted (unless...)". While the strict meaning of this can be considered the same than "it's acceptable", clearly the tone and intention is not the same.
                          Unless = it is acceptable in certain conditions. Not desirable, but there are situations where it is the correct course of action.

                          "... unless the ability of the plane to fly...". This is absolutely different to "the airworthiness".
                          Airworthiness = the ability of the plane to safely fly and land. But call it 'the ability of the plane to fly' if you wish.

                          "... is in SERIOUS doubt". The stress on SERIOUS is in the voice of the narrator.
                          Doubt = a feeling that something is preventing liftoff.
                          Serious Doubt = a strong feeling based on professional experience that something is preventing liftoff.

                          And don't forget the "... best to continue the take-off and deal with the problem in the air" part.
                          It is always best to take-off. That doesn't mean anything if it won't take off.

                          Forget about the speed. The moment that you judge that the plane can't fly you abort no matter what speed. As long as you don't reach that judgement, if you are past V1 you go.

                          The decision is and must be based on the PIC's judgement of the ability of the plane to fly. And to your dismay, it's a judgement call. No strict procedure can be written on what constitutes a "won't fly" judgement.
                          V1 is not a judgement call because it can be calculated. Can we not also use computational power to calculate a speed beyond V1 where the a/c will depart the runway during RTO at or below [x] kts, [x] being the allowable limit for a controlled crash beyond the runway? Call it Vrto or something...

                          V1 is also calculated beforehand so the pilot does not have to make spontaneous calculated estimations. A Vrto would have the same value.

                          The problem with leaving this to pilot judgement involves the same human factors as leaving the decision to continue a landing without the runway in sight (go-itis, blind confidence, compromised situational awareness, risk taking).

                          PIC: Oh, well. V3. Reject...
                          I'm going to make a judgement call that rto should definitely occur before flap retraction speed...

                          Comment


                          • #88
                            Note what you say Gabriel. The run off is 550m/1811ft from the threshold to the hedge line with a further 94metre/288ft metres to the edge of the ditch. Sounds a lot but an aircraft travelling at speed with difficult retardation on grass for at least half those total distances is going to eat that up in seconds. From the marked end of the runway to the end of the tarmac is 320m/1055ft, from there on its grass and hedges.

                            The big issue here though is that there is a bloody great ditch at the end of it all.

                            Airport management to pilots and passengers.... "Right folks, there's a total of 640 metres, half of which is grass for you stop in while you are frantically trying to work out what to do for the best. After that, your arses are ours when you hit the ditch at the end. We could install some safety arresting equipment but it costs too much and the shareholders will lose out on their annual bonus."

                            They say a picture speaks a thousand words. This could help illustrate what the pilots had to contend with. The yellow line is the distance that a Gulfstream 4 needs to get airborne at MTOW. The word DIE is where they did exactly that.
                            May all rest in peace.

                            Last edited by brianw999; 2014-06-11, 13:19.
                            If it 'ain't broken........ Don't try to mend it !

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                            • #89
                              BTW: I acknowledge that in fields where end-of-runway hazards such as a seawall or a ravine exist Vrto might be at or just slightly beyond V1, before it would be possible for a pilot to establish serious doubt of the ability of the plane to fly. There are fields where, if you can't lift off after V1, you are dead in any case.

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                              • #90
                                Originally posted by brianw999 View Post
                                Airport management to pilots and passengers.... "Right folks, there's a total of 640 metres, half of which is grass for you stop in while you are frantically trying to work out what to do for the best. After that, your arses are ours when you hit the ditch at the end. We could install some safety arresting equipment but it costs too much and the shareholders will lose out on their annual bonus."
                                Hopefully future airports will be DESIGNED to address the problem of RTO accidents rather than the current policy of addressing this in the cockpit alone.

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