Originally Posted by
lomapaseo
I don't recall any military jets falling out of the air at high altitudes. Do you suppose that air friction might be significant in limiting the metallurgical effects
I share your confusion over the newly suggested fact. The possibilities are
- above tropopause the temperature gets warmer
- we're discussing ISA -20 conditions so far, which at high flight levels are quite rare (frequency of exposure) yet encountered repeatedly by civilian craft on polar routes
- military would not stay in such cold air mass for the duration of many hours unless purposely built
- it could be a case of certification / guaranteed performance / uncharted territory
- higher TAS and Mach do make a difference, for the cold fuel case that's what the QRH drill is
Still sounds a far fetch.