JamesT73J
11th Oct 2003, 23:47
I recently had an enjoyable (if delayed) flight on a 737-700 from Gatwick. On boarding the aircraft, two things struck me as quite unusual; firstly, it was very warm, easily about 25 degrees, and secondly, it was completely silent - there was no sound from the aircraft at all, although the cabin lights were on.
Then, the main lights went out, leaving just the emergency exit signs on. There was a two-tone warble from the cockpit which I'm guessing was the master warning sound. The captain them came over the PA and advised that "ground power had just been switched off for some reason", and that we had to wait for it to come back on again. After that, things went like clockwork.
What I was curious about was the APU; I thought this provided both electrical current and bleed air for the enviromental systems? I understand it cannot be heard from the cabin, so I don't know if it was running or not. Just wondering if this is a normal phenomenon; My best guess was that they just chucked all the passengers on at a stage before these things happen. Anyone enlighten me?
Then, the main lights went out, leaving just the emergency exit signs on. There was a two-tone warble from the cockpit which I'm guessing was the master warning sound. The captain them came over the PA and advised that "ground power had just been switched off for some reason", and that we had to wait for it to come back on again. After that, things went like clockwork.
What I was curious about was the APU; I thought this provided both electrical current and bleed air for the enviromental systems? I understand it cannot be heard from the cabin, so I don't know if it was running or not. Just wondering if this is a normal phenomenon; My best guess was that they just chucked all the passengers on at a stage before these things happen. Anyone enlighten me?