Hi
How long do pilots take before the beginning of a flight to set up the cockpit from cold and dark (B737).  And do airliners completly shut down the planes between flights or do they leave the APU running.

Regards.....Chris

It depends really. Overnight stays, obviously everything is shut down. Other than that, it's really a matter of time. If you are emptying the airplane and then immediately handing it over to another crew, you might leave anything that takes a long time to warm up on. I know that at some airports in my 727 First Officer days we would leave the number 2 engine running for power at times, even when no one was near the plane. Lots of Dash-8 pilots will leave an engine on to provide electrical power but disengage the props. Preflight can take from 15 minutes to an hour depending on the plane and the flight. ETOPS flights over the ocean usually have long preflights, whereas a 20 minute hop in a turboprop has the bare minimum, "let's just check everything and get airborne" inspection.