A320 Taxi
When doing a single engine taxi out, I've been told by a friend that the second engine must be running by the time the aircraft enters an active runway. So, even if entering a runway to backtrack (like 14 at EGNM), the engine must be running.
Why is this? I can understand that the engine must be running for at least two minutes before takeoff, or you get a CTR Tank warning, but why can't you save fuel at somewhere like Leeds on 14 and start the engine whilst going up Rwy 32 to backtrack onto 14? Why must the engines both be running by the time you enter the runway?
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