I have a couple of problems with what was said in that interview 1 I did not think an APU starts automatically It s normally started manually For example with US Airways Flight 1549 both engines were down and it was Sullenberger s decision to start the APU immediately after the bird strike was credited as one of the things that allowed for a safe landing The power from APU meant that the aircraft stayed in normal law mode Had the flight deck lost power the fly by wire system would have switched to alternate law and there s a good chance the aircraft would have crashed hard The point here is that the APU start was not automatic on an Airbus A320 2 while some APUs have their own fuel source jet aircraft APUs normally run off jet fuel from one of the main tanks We would need very good WP RS to show that the 777 s APU would do an automatic start on loss of power or fuel and that it is able to run for five minutes after the main tank is empty There s also the issue that it s unlikely the fuel tanks ran dry at the same instant and that the APU was connected to one tank The Partial Ping has not been explained well enough for us in the public to make an informed call on what it was