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kmanning

Climb 1 or Climb 2 in the 747-400

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Hi all, I could not find this information anywhere. But does anyone know when 747 pilots select climb 2 in the FMC? I know that climb 2 has a less climb thrust than climb 1. Do 747 pilots select climb 2 when the aircraft is at a certain gross weight since the airplane doesn't need as much climb thrust at lighter gross weights? If so, what is that weight?Ken.

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On the Virgin 744 DVD, Allan uses Climb 1 at a GW of just around 360tonnes. "Do 747 pilots select climb 2 when the aircraft is at a certain gross weight since the airplane doesn't need as much climb thrust at lighter gross weights?" - Yes, to save fuel and make lesser noise and it does not make as much wear and tear on the engine.Martin

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Selection of CLB, CLB 1 and CLB 2 is automatic. When you enter the Sel temp TO derate, this moves the caret adjacent to these selections. The FMC is programmed this way.Probably more technical that you need to know, but... one of the important things to consider is that there needs to be a thrust change when you go from TO to CLB. If you select a large TO derate, but manually select no derate for climb, TO thrust and CLB thrust may be about the same. If the throttles don't physically move (about 3 degrees), the engine management system may not unlock (the EEC's may stay in a kind of HOLD mode) and won't immediately start trimming (to give equal thrust on all 4 engines) .... until a much higher altitude (AGL), i.e. 4,500' AGL instead of 400'AGL.Cheers.Q>

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