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I am not aware of a single case where 2 turbine engines failed randomly and independently of each other. In all the cases that I know both failures were correlated by a common or consequential cause. Fuel starvation, fuel exhaustion, fuel contamination, flying pieces of an engine (or the whole engine) hitting the other engine, volcanic ashes, birds, severe water injection, severe hail damage, fuel frozen, ice clogging of the oil-fuel heat exchanger, same maintenance mistake done on multiple engines, shutting down the wrong engine, and overstressing the remaining engine. As I said before, if the probability of an engine to fail is X, the probability of a second engine to fail once the first one already failed is much greater than X. Still very very low, but not nearly as low as just a random engine failure.And much more likely than a meteor.
Most of those causes you listed would have the engines failing either simultanously or within minutes of one another. Context is important here. If you have a non-recoverable engine stall in one engine while the other shows no signs of trouble over a number of minutes as you are working the problem, there is a very low chance that the second engine will fail. You have to take that into account. Again, I don't like the idea of straying too far from a runway with no propulsion redundancy, but I also acknowledge that the risk in doing so is quite remote.
But, as you insist that landing over MLW is of no real concern, I have to question the wisdom of not doing so.
But engines usually show some signs of trouble before conking out completely.
Are you sure? I am not, either way. But I am sure that many (not necessarily most) engine failures happen with no or little warning.
Sure, a coincidental catastrophic failure of the remaining engine could hypothetically occur. Then what do you do? Or a meteor, of course...
"Coincidental" means just that they happen together but it doesn't say anything about independence of events. The failure of the second engine can (and has always been proven to be) be much ore than just "coincidental".
I am not aware of a single case where 2 turbine engines failed randomly and independently of each other. In all the cases that I know both failures were correlated by a common or consequential cause. Fuel starvation, fuel exhaustion, fuel contamination, flying pieces of an engine (or the whole engine) hitting the other engine, volcanic ashes, birds, severe water injection, severe hail damage, fuel frozen, ice clogging of the oil-fuel heat exchanger, same maintenance mistake done on multiple engines, shutting down the wrong engine, and overstressing the remaining engine. As I said before, if the probability of an engine to fail is X, the probability of a second engine to fail once the first one already failed is much greater than X. Still very very low, but not nearly as low as just a random engine failure.And much more likely than a meteor.
One thing is to take your time to stabilize and and do everything methodically and correct (i.e. without rushing or cutting corners). Another is stabilize, do everything methodically and correct, and THEN fly another hour to burn or dump fuel. I must be missing something, but look at this example. They landed about 40 minutes after the mayday, instead of say 10 to 15 minutes. They went out to about 100 miles from the airport (at 10,000 ft) instead of staying within 40 miles (if they had completed the return without dumping they apparently intended initially). I and trust these guys!
BTW, I'm not saying this doesn't bother me. If they were at 10,000, I'm guessing they could glide about 25nm at best. But engines usually show some signs of trouble before conking out completely. Sure, a coincidental catastrophic failure of the remaining engine could hypothetically occur. Then what do you do? Or a meteor, of course...
What is "in proximity"? A certain distance? A certain time away? Gliding distance? Did El Al remain "in proximity"?
Well, if you aren't making an immediate return, I guess that's up to ATC (they can't have you dumping fuel on other traffic). But the closest suitable ATC...
Indeed. I hadn't considered those things. But I think we can now agree that the FAR's does not require an immediate return after a single engine failure on a multi-engine aircraft. It merely requires designating your return/diversion the closest suitable airport in terms of time. So, you can go in asap or you can hold to burn/jettison fuel as long as you ultimately land at the closest suitable airport in point of time from the location where the failure occurred. This assures that, at any time during the hold, you remain in proximity to the closest suitable airport as opposed to increasing the distance to the closest suitable airport by burning fuel while traversing to another one.
What is "in proximity"? A certain distance? A certain time away? Gliding distance? Did El Al remain "in proximity"?
I don't know what the exact intent of the rule is. But I will tell you one thing: My confidence in a safe outcome is very high in either way, but not equally high. Remaining in "close proximity to the airport" doesn't increase significantly my confidence in a safe outcome. Landing ASAP* (even above MLW) would.
* (ASAP includes all the provisions for stabilizing, running required checklists, securing the cabin, and flying a reasonable non-aerobatic approach)
No, it is not redundant. You can have an airport 30 miles ahead and another one 10 miles back. If you can shoot a straight-in final for the one 30 miles ahead but for the one that is 10 miles back you need to first turn 180 degrees, then fly a downwind, base leg and final, you will probably land much sooner in the one that is 30 miles ahead. If you have one airport 10 miles from you in IMC requiring a full instrument procedure, and another one 30 miles from you that is visual, you can probably land sooner in the one that is 30 miles away. If you have one airport that is 10 miles from you but you are at 39000 ft, you will need to fly more than 100 miles anyway to get down. Etcetera.
Actually I think that the "in point of time" is a relatively modern addition, not the original wording of the rule, which was added precisely to mean that you don;t need to land at the airport that is the closest if you can land at another airport sooner on in the same time.
Indeed. I hadn't considered those things. But I think we can now agree that the FAR's does not require an immediate return after a single engine failure on a multi-engine aircraft. It merely requires designating your return/diversion the closest suitable airport in terms of time. So, you can go in asap or you can hold to burn/jettison fuel as long as you ultimately land at the closest suitable airport in point of time from the location where the failure occurred. This assures that, at any time during the hold, you remain in proximity to the closest suitable airport as opposed to increasing the distance to the closest suitable airport by burning fuel while traversing to another one.
I'm quite convinced that it means "the nearest suitable airport in terms of time".
That last part is, or course redundant unless you are in a mountainous area below the surrounding MSA.
No, it is not redundant. You can have an airport 30 miles ahead and another one 10 miles back. If you can shoot a straight-in final for the one 30 miles ahead but for the one that is 10 miles back you need to first turn 180 degrees, then fly a downwind, base leg and final, you will probably land much sooner in the one that is 30 miles ahead. If you have one airport 10 miles from you in IMC requiring a full instrument procedure, and another one 30 miles from you that is visual, you can probably land sooner in the one that is 30 miles away. If you have one airport that is 10 miles from you but you are at 39000 ft, you will need to fly more than 100 miles anyway to get down. Etcetera.
Actually I think that the "in point of time" is a relatively modern addition, not the original wording of the rule, which was added precisely to mean that you don;t need to land at the airport that is the closest if you can land at another airport sooner on in the same time.
I don't like the wording either, but what else could "the nearest suitable airport, in point of time" mean? Have you heard of the "near future"?
I'm quite convinced that it means "the nearest suitable airport in terms of time". That last part is, of course, redundant unless you are in a mountainous area below the surrounding MSA. Perhaps that is why it is added. I take it to mean "stay close to the airport in case an immediate landing becomes necessary" (as opposed to "land immediately"). The wording suggests it might have been carried over from the early days of aviation (such as the use of the word 'field' in reference to modern airports).
One thing is to take your time to stabilize and and do everything methodically and correct (i.e. without rushing or cutting corners). Another is stabilize, do everything methodically and correct, and THEN fly another hour to burn or dump fuel. I must be missing something, but look at this example. They landed about 40 minutes after the mayday, instead of say 10 to 15 minutes. They went out to about 100 miles from the airport (at 10,000 ft) instead of staying within 40 miles (if they had completed the return without dumping they apparently intended initially). I and trust these guys!
It definitely shows the confidence of the crew and the controller in the reliability of the second engine. Sending them off the holding pattern was probably due to traffic (we can't be dumping fuel on other aircraft). Correct me on this, but I think you need about 4000' of vertical separation and about 1nm of lateral seperation per 1000' of that vertical separation to assure complete evaporation.
I also assume that by the time the crew accepted the option to dump fuel, they had shut down the affected engine and determined that no fire was present.
I am a native English speaker and I find that phrase hard to decipher. I suspect it was written by committee to be intentional vague.
It means nothing, grammatically. A "point of time" refers to a moment in time. Even dismissing the missing article, in "a moment in time" is meaningless there.
It could mean 'closest in terms of time' rather than 'closest in terms of distance', but that also seems meaningless.
What it doesn't say is "in the shortest possible span of time", "without delay", "as soon as possible" or "immediately", which is what you would expect there if that was the expressed directive.
I think it's left open to pilot judgment, as long as the pilot doesn't stray from the nearest suitable airport.
I don't like the wording either, but what else could "the nearest suitable airport, in point of time" mean? Have you heard of the "near future"?
And, again, I agree with you on landing asap if there is no reason not to. But the question I'm asking (what 3WE calls 'disdain') is why pilots often don't do this. I suspect it might have something to do with the relative safety of single engine ops near the runway and the wisdom of stabilizing and taking your time to do everything methodically and correct. But it is puzzling...
One thing is to take your time to stabilize and and do everything methodically and correct (i.e. without rushing or cutting corners). Another is stabilize, do everything methodically and correct, and THEN fly another hour to burn or dump fuel. I must be missing something, but look at this example. They landed about 40 minutes after the mayday, instead of say 10 to 15 minutes. They went out to about 100 miles from the airport (at 10,000 ft) instead of staying within 40 miles (if they had completed the return without dumping they apparently intended initially). I and trust these guys!
Quoting... ahem... Heidegger... (which I rarely do on this forum): "What is incalculably far from us in point of distance can be near to us."
He is supplanting the word 'terms' with the word 'point'. Of course he is doing this in archaic language, but it stands to reason then that 'in point of time' is synonymous with 'in terms of time'.
I suppose someone at the FAA could have had a fetish for old-timey diction...
I am a native English speaker and I find that phrase hard to decipher. I suspect it was written by committee to be intentional vague.
It means nothing, grammatically. A "point of time" refers to a moment in time. Even dismissing the missing article, in "a moment in time" is meaningless there.
It could mean 'closest in terms of time' rather than 'closest in terms of distance', but that also seems meaningless.
What it doesn't say is "in the shortest possible span of time", "without delay", "as soon as possible" or "immediately", which is what you would expect there if that was the expressed directive.
I think it's left open to pilot judgment, as long as the pilot doesn't stray from the nearest suitable airport.
And, again, I agree with you on landing asap if there is no reason not to. But the question I'm asking (what 3WE calls 'disdain') is why pilots often don't do this. I suspect it might have something to do with the relative safety of single engine ops near the runway and the wisdom of stabilizing and taking your time to do everything methodically and correct. But it is puzzling...
Colicky today? Just discussing a grey area and what might cause a crew to return asap (as this one did) vs burn/jettison fuel (as others have). Did that really throw you into a 72pt rage?
Colicky, no. Just amazed at how your disdain for pilots and your home base that they are always wrong, blinds you from seeing that 1) they didn't land immediately nor 2) they used good procedures and made good decisions...but, no, 72 pt font is no match for your closed mind.
... but the stated directive is still for distance, not time.
Is it? I am not a native English speaker, but...
§ 121.565 Engine inoperative: Landing; reporting.
(a) Except as provided in paragraph (b) of this section, whenever an airplane engine fails or whenever an engine is shutdown to prevent possible damage, the pilot in command must land the airplane at the nearest suitable airport, in point of time, at which a safe landing can be made.
I would submit to you that, at any time during the fuel jettison process, should a problem with the remaining engine arise, you can always terminate that process and land asap, so the concern is still distance to the nearest suitable airport. During that entire hour of burning fuel, you are remaining in the same close proximity to the nearest suitable airport.
Within gliding distance? And even if yes, gliding a transport category aircraft still involves a lot of risks.
But I do understand why that might not be the best option from the airline's point of view and (if the engine is shut down in a timely manner) it might not be significantly more dangerous to minimize the outcome for their precious assets. I think this is why these events are often followed by fuel burns or jettisons.
Best option for the plane (i.e. for the $$$) and not significantly more dangerous for the persons? i side with the persons (and with you that don't want to waste time dumping fuel).
Nearest suitable airport, IN POINT OF TIME, at which a safe landing can be made.
So for me the question is just: Can a safe landing be made without dumping / burning fuel? If the answer is YES, then other options should be discarded unless they are deemed SAFER (not just not significantly more dangerous). Again, that's my point of view. The FAA, airlines and pilots don't seem to agree with me, and they probably have a good reason. I just fail to see it.
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