By the way, another thought occurred to me this evening as I was reminded of my new humbleness at being corrected about basic things about the Boeing 747, was the APU on during the event times for China Airlines Flight 611, Air India Flight 182, United Airlines Flight 811, Pan Am Flight 103, Trans World Airlines Flight 800? Is there a way to tell by the FDR if the APU was on? I often see the APU contrail between the engine contrails as the 747s fly overhead.
Well Barry, here is another 747 lesson for you:
APU bleed air can be used during takoff and to a
maximum altitude of
15,000ft . However in normal operational practice, the APU is switched off after engine start. If I were you, I would stick to your hobbyhorse of midspan latch failures, it's getting a bit embarrasing old chap.