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Old 07-19-07, 10:24 AM   #23
Chock
Sea Lord
 
Join Date: May 2005
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Quote:
Some pilots raised suspicion over the computer system of the plane, wondering if it could've prevented the pilot from maneuvering more aggressively, but only the black box can tell if such a thing happened, if the crew deactivated the restrictions or none of the above.
If the pilots had decided to abort the landing and take off again (and it does look very much like that from the terminal footage of the aircraft speeding along the runway) they would presumably have engaged the TOGA (take off/go around) mode on the throttles. Doing this should automatically throttle up the engines to take off thrust and configure the aircraft for a go around. So, unless they didn't do that, it would seem unlikely that the flight control systems would be limiting the aircraft's manoeuverability. They could have just rammed the throttles forward manually in a panic (which would be understandable) and in theory this would have worked if they had retracted the flaps from the landing configuration to the take off configuration, but there are two problems with doing it that way:

The first is that jet engines spool up slowly. Even if you've never piloted an a multi-engined aircraft, it is likely you've flown on one, in which case you will probably have noticed that the pilots do not simply 'firewall' the throttles all the way forward while at a standstill, they advance them smoothly forward in several stages to prevent the possibility of one engine spooling up to full power faster than the other. This is to avoid the possibility of asymmetric thrust initiating a swing to one side, which would be difficult to correct while there is not much airflow over the rudder. So if the pilots in this tragedy had panicked and rammed the throttle forward and it had initiated a swing, this might explain the turn the aircraft made and the difficulties they got into.

The second, is that in addition to increasing lift, the flaps also increase drag (which slows the aircraft down on its approach descent) but on a take-off roll, this drag would be undesirable, so minimal flap settings are the order of the day on take off, with anywhere between about 5 and 20 degrees of flap usually being the case for a take off, the less the better if you have enough runway length. Flaps do not retract instantaneously , they take time to come in, and while they are deployed, they cause a lot of both aerodynamic and form drag. Both of which would inhibit the aircraft's ability to accelerate to a safe lift off speed.

Of course on an approach to an airstrip with such a reputation as this one has, it should be the case that the crew conduct a thorough pre-landing briefing on what exactly they will do in all eventualities, including an abort on the landing roll out. Given the circumstances, and if they did in fact carry out such a briefing, things should have gone better than they did. But...

It is easy to be judgemental about pilots decisions in such events, and if in a panic the crew had differed on what to do, it would certainly not be the first time this had happened. Numerous crashes of this nature have occurred when the pilot and co-pilot were literally arguing about whether to continue braking, or to go around. On some occasions in the past, this has even involved pilots fighting over whether to press the TOGA lever or not, with it being switched on and off by both the pilots as the aircraft careered down the runway!

Having had an emergency on landing in real life whilst piloting an aircraft, I would like to say that I coolly handled it with no panic whatsoever. But the truth is that on that occasion, I was scared, and I actually 'froze up' for about two seconds (seemed a lot longer at the time - almost like one of those slo-mo bits in a movie) before snapping out of it and then doing the right things, which fortunately meant that I was able to land okay. I was lucky in that most aeroplanes will quite happily fly themselves for a few seconds on such occasions! This is what pilots jokingly refer to as 'the Jesus manouever', as in: 'Okay Jesus, you have control!'.

So I am rarely judgemental about decisions from pilots in circumstances such as these, because I know that things like that can happen. But you will notice from the quote above that it is rare for pilots to admit to this kind of fallability in their profession, and so the first thing most pilots would claim is that 'the plane wouldn't let me do this', when what they really mean is 'the plane couldn't do that because I had the systems set up incorrectly'. This is understandable because it is a favourite of air accident investigators and aeroplane manufacturers to blame pilots who die in crashes for the cause, and then quietly fix the real issue a few months later. So naturally pilots get a bit defensive on such matters.

I guess we will find out what happened if and when the flight data recorders remained intact and were working properly.

Chock
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Last edited by Chock; 07-19-07 at 10:34 AM.
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