Originally Posted by
SirRagnar
I would think it has something to do with safety. I remember seeing an Air Crash Investigation on National Geographic which was partly caused by sitting on the tarmac with the aircon running for a long time before taking off.
That will heat up the aircon system significantly and apparently that is (at least in that plane) sitting right below one of the fuel tanks.
I am just speculating though, but I'm sure someone knows the exact reason and will pass by and tell us
Saw the same program on NGC a year ago, and apparently there was something with the insulation of the wiring that sparked and being placed near the fuel tanks the fuel vapor ignited and the thing blew up. This happened a decade or two ago, so it's no longer a risk.
Check for same query... ^