Re TAT and minimum fuel temp
Slightly off thread, but why do all the text books say that the fuel temp will not decrease below TAT (transient effects aside)? TAT is reached only at the stagnation point, the rest of the wing surface (with which the fuel is in contact, after all) will be at a lower temperature, on average about SAT, but the upper surface will be lower still ('cos its lifting, hopefully). Chambudzi's post earlier suggested that on the same day his fuel went on cooling well below the TAT of -37, so perhaps we shouldn't regard this as more than folklore. No one ever explained it properly to me while I was aviating. Doesn't alter the fact that we have all seen temperatures as low as -44 in flight, but no engines stopped until Jan 17, and then only a long time after the minimum temp would have been reached.