Frost and positive TAT
To Chris Scott and snowfalcon2:
I've checked A.net pictures as well today and came across almost the same pictures snowfalcon2 posted. I agree with you that actual fuel quantity is probably somewhat more than the frosted area for the reasons you explained. Making it only more likely there was sufficient fuel in the tanks before the moment of impact.
For it being a rare condition to observe frost on the lower wing surface, that may be when searching photographs for examples. But since I've performed countless post flight inspections and also participate in de-icing activities as a supervisor in winter seasons I come across frosted lower wing surfaces quite regularly if the weather conditions are right for it. Indeed the fuel level in the tanks usually exceeds the frosted area somewhat which can be observed by a wet thawed area bordering the frost at + deg. C conditions. This condition cannot be determined from the G-YMMM subject photograph but was probably present.
Therefore, I do believe the fuel quantity in G-YMMM's case was slightly more than the frosted area in the picture and will take it into account when making any calculations. However, I'm still convinced that the center wing tank was empty when observing the clear outline of frost starting at the rib, separating wing tank(s) from center wing tank. Also because of the absence of frost near the wing root.
Green-dot
Last edited by Green-dot; 13th Apr 2008 at 22:28.