Originally Posted by
PENKO
But the issue is the same on all aircraft, from 747 to Cessnas: the urge of some pilots to invent procedures based on unverified, unofficial conjecture, sometimes called mechanical sympathy our even airmanship...
Maybe he should ask the captains exactly which parts of the APU need warming up. The core of a cold soaked APU will never reach anywhere near ambient temperature in the ten minutes it takes to taxi to the gate IMHO.