Originally Posted by
BoeBus
What does the aircraft do for power in these situations? I imagine that the engines would have been shut down and even the APU wouldn't last (or shouldn't be used) for 5.5hrs. With either APU or engines, would the plane not run out of fuel? Was it connected to a ground power unit and what happens when it has to go "around the block"?
There isn't any issue using an APU for this period of time. In fact due to the lower fuel burn would be preferred. At 5.5 hours the fuel burn from the APU plus the occasional use of main engines to move around wouldn't use much fuel (about 1-2 tonnes for twins, and about 2-4 for quads). This would only use about 25% of the remaining fuel you'd have on board when landing.