CDU Preflight, Boeing 738
Thread Starter
Joined: Jul 2006
Posts: 123
Likes: 0
From: Norway
CDU Preflight, Boeing 738
Dear folks
How come we enter the OAT into the FMC CDU during preflight of the Boeing 737-800?
I know one gets a reduced max thrust available if one doesn't.
Is it because the TAT-probe needs one pack functioning to give a correct readout to the ADIRU? But then again.. one would have ample time for OAT readings after startup and prior to T/O if this was the case.
How come we enter the OAT into the FMC CDU during preflight of the Boeing 737-800?
I know one gets a reduced max thrust available if one doesn't.
Is it because the TAT-probe needs one pack functioning to give a correct readout to the ADIRU? But then again.. one would have ample time for OAT readings after startup and prior to T/O if this was the case.
Joined: Mar 2001
Posts: 4,563
Likes: 35
From: I wouldn't know.
The 737 is available with or without aspirated TAT probe. If you have the unaspirated one your TAT before takeoff will creep up within 2 or 3 minutes to 99°C (and more, but that isn't displayed) after probe heat is switched on, invalidating any data based on that. Even the aspirated probe is often considerably off the real OAT, depending on position vs. the sun and other factors.
