Alf5071h said:
<<<John, the answer is partly in your guess. It is very difficult to quantify; manufacturers may even have different or even opposing techniques amongst their aircraft types. It is not just about improving the published stopping distance, which in normal (regulatory approved) operations should have sufficient safety margin, but also about many other aspects of control on the runway, which may not have such generous margins, e.g. crosswind.
>>>If margins were sufficient, there wouldn't be so many overruns. Runway side excursions are probably more about crosswind technique, gusting crosswinds and/or momentary loss of visibility (e.g. link). Off-the-end overruns tend to be more about landing long and hot where there's inadequate braking because of the slippery surface. That's where backstick braking comes in as a means of improving upon the situation that a pilot is stuck with - once in reverse.
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<<<I have sat in many meetings similar to those related by MFS; in addition to manufacturers asking ‘why did they do that’, chief pilots should consider ‘could their pilots do that?’.
>>> In challenging conditions the PF should be the captain. If a captain cannot embrace a simple handling technique, then that organization should look closely at its own upgrade standards. It's not as if it's not replicable in a simulator. <<<Many people cannot contemplate the range of situations they could encounter or put themselves in, or the behaviors that pilots might (or in fact do) exhibit. Even when individuals consider ‘could it ever happen to me?’ a realistic answer may only be available in hindsight through analysis and understanding, only then is the error provoking situation or the personal behavior seen to be hazardous.
>>> Hmm, take a simple handling nuance and surround it with portentous fear and ominous loathing. A little OTT I feel.
<<<Part of this discussion is about discipline, the need to follow procedures and avoiding hazardous attitudes such as ‘I can do’. Similarly, there is the need to resist peer pressure, which is not aided by well intentioned suggestions that are promoted beyond responsible boundaries.
>>> Authoritarian suggestions of latent irresponsibility deteriorate in the following sentence to good old placatory and advocatorial homilies. Yet it does nothing to add to the discussion and is quite devoid of useful relevant argument.
Discipline is the foundation of airmanship; this thread also relates to other qualities such as skill, knowledge, situation awareness, and judgment.
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<<<In seeking an end to runway overruns, pilots’ need thinking skills in addition to those of flying, they need greater knowledge of the regulatory assumptions to identify those situations where the margins in landing distance are significantly degraded, or the unreliability of braking coefficient values that could lead to misunderstanding the situation. These aspects have been discussed in related threads.
>>>Strictly by-the-book stuff. ALF, methinks that you are ignorant of (or forgetting) that arriving on "perhaps contaminated" marginal runways is a totally inexact science. In fact it is a "no mans land" full of hidden mines. That aspect and all the operational pressures, subtle and unsubtle, is being neatly side-stepped by you ALF. Pilots also need to be well insulated against fatigue and errors of judgment when the adrenaline suddenly cuts in and they're down and in reverse and truly have nowhere to go but off the end - "insulated" by having a fall-back position. So if somebody in the RHS (or LHS) is aware of this backstick braking technique and later honestly attributes not overrunning to backstick braking, are YOU going to issue plaudits or censures? Good risk management is all about providing accessible fallback positions..... not arbitrarily curtailing them by decree.
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<<<An overview of accident reports identifies two fundamental causal themes, either the crew did not understand the situation, of if they did, then they chose the wrong course of action.
>>>Dishonestly simplistic. <<<If pilots have to consider alternative techniques on the runway then they have failed in the first instance, misjudging the situation, the need for a go around, as well as not applying their skills to land at the correct speed or position;
>>>and therefore deserve to have an accident but only in the approved manner. <<<if they had been successful in these aspects then there should be no doubt about stopping. However, having made such mistakes and arrived on the runway, a back stick technique is not guaranteed to recoup the hazardous situation and may make it worse.
>>>....so these pilots and their pax should just take their lumps in the approved manner by actively discarding such potentially disastrous and unapproved last-ditch measures such as backstick braking. By "may make it worse" ALF is suggesting that the accelerating qualities of backstick braking are as yet unknown.... but suspected to be potentially lethal. If not, then what is being suggested?
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<<<A quick and un-scientific assessment of recent accidents (before the facts are known) suggest that a small increase in braking effectiveness at high speed would be unlikely to have prevented the result; it might have alleviated some of the consequences, but equally it could have resulted a lateral deviation into far greater hazards (N.B. Toronto wind shift and off-runway hazards).
>>>But notwithstanding that it's "before the facts are known" (which they generally are BTW), ALF is suggesting that unapproved and untested potential solutions by known heretics should be discarded as potentially even more dangerous (than a total hull loss and a very near loss of 300 souls). Really? That's really forward thinking and progressive stuff. No wonder we are seemingly stuck in the overrun rut. Reality check required here methinks. Grandiose verbiage but quite lacking in incisive thought processes.
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<<<Of the 5 or so overrun accident investigations that I was associated with, none would have been prevented by a small increase in braking effectiveness.
>>>When all else fails and you've lost the argument, concede that "in the bigger picture" the advocated effect could only ever be "small". Well in fact it's about 20% at least - and that's not "small" in overrun terms. It can make a 5000ft runway in effect a 6000ft runway (or a 6000ft runway a 7200ft one). Nothing small about that in overrun terms. <<<The majority had root causes involving human behavior in the air, the others, human error on the ground, which involved perception and incorrect use of retardation devices.
Thus, we already have large variability in human behavior before anyone adds more from aircraft control techniques.
>>>And perish the thought that we should ever offer a straw to a drowning man that's made a "human error on the ground", complete with the sudden realization of just having built his own funeral pyre. Yes, perish that thought. Reversed mixed metaphor: burning men normally jump into water and drown - but it makes the point that once on the ground, there's no "going back", only the possible redemption offered by backstick braking. QF1 in BKK created its own marginality by constructive indecision about "whether to go or try to stop?". Maybe having a fallback position of backstick braking would remove that now familiar "sudden uncertainty". Think about that aspect. Pilots under duress do need an "equalizer". It shouldn't be denied them by puffball prohibitionists in exalted positions.
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They're certainly turning out a thicker more durable and obdurate brand of closed-mind Luddite nowadays. Oh for a cogent argument with some real substance, pith and apple-vinegar.
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And JF. Not a failure in any sense. Your input is always valued (by operators anyway). Your last posting's brevity was perhaps more impactful than my assuredly futile counter-points above.
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And one final point. Backstick braking is by no means new. Search the web and you'll find some few references to it. It's just that it was perhaps never really understood, despite being taught to "the old school" military. In the age of autobrake and anti-skid it has now however "come of age" again. I would be surprised if one (or both) of the two major manufacturers didn't someday automate it.