tanimbar,
Thanks a lot for your post. It was interesting reading. I'd like to comment on a few minor points.
Originally Posted by tanimbar
As it is, the AAIB, RR and Boeing, are left with a mystery. They strongly suspect the fuel was degraded in some manner, due to the exceptional environmental circumstances of the flight, but cannot yet prove it or, at least, demonstrate that this is the most likely cause of the accident.
(my emphasis)
To be nitpicking, the AAIB quoted the meteorological services as saying that the conditions encountered by BA038 were "unusual", but "not exceptional".
Possibly the AAIB/Boeing et al will commission a test 777. Time is critical: the authorities need an answer before the northern hemisphere winter arrives, but commissioning a test flying 777 will take months and, even assuming they act quickly, the only test area available now is Antarctica! Anyone seen a strange 777 in southern Chile/Argentina??
I'm curious to see if they're going to go that far.
So, I'm assuming the present testing/research will be inconclusive and the AAIB will issue another bulletin towards the end of 2008 that will contain operational changes (actually, I expect that a draft of this bulletin has already been written). In other words, the precautionary principle will be
applied:-
1) avoid prolonged flight in very cold air masses
2) if 1) cannot be followed then loiter, in some way, until fuel is warmed.
Here we may have a problem. According to the recorded data, the fuel still was relatively warm. So there would have been no need to get it warmed any more.
Lowest recorded fuel temperature was -34C, so 23 degrees above the measured freezing point, and still 13 degrees above the specified freezing point for Jet-A1, and 18 degrees above the specified freezing point for the Chinese fuel type they were actually carrying. If left unchanged the warning would have been triggered at -37C, 3C above freezing point for Jet-A. They were still even above that.
Originally Posted by rubik101
I followed a BA 777 across Poland/Germany to London a few nights ago. He asked for descent when over Berlin to FL340. When asked by Berlin for the reason, the reply was, 'Fuel Temperature' so I guess new procedures are already in force.
Descents for low fuel temperature are normal, when the temperature reaches the threshold (at least 3 degrees above fuel freezing point)
The Manual advises that when that happens, to either descent to a lower (warmer) altitude or to increase cruise mach to increase TAT. Both carries a fuel consumption penalty, and I guess the decision is the PIC's.
Bernd