I use TOPCAT and she tells me if I need to TO-1 TO-2 and how much too derate, my question is, when do I use the CLB derates and how much and which one, I dont really understand this?Cheers

Hi,When you select TO derate and/or assumed temp the fmc suggests clb, clb1 or clb2 by itself which is suitable to your TO config. Ofcourse it is up to you to accept it or not but I had no issues using the clb derate the fmc suggests.Doruk Selçuk

Hi,When you select TO derate and/or assumed temp the fmc suggests clb, clb1 or clb2 by itself which is suitable to your TO config. Ofcourse it is up to you to accept it or not but I had no issues using the clb derate the fmc suggests.Doruk Selçuk

HeyQuick question: using the derates, ever tried to cut one engine after V1? Is it still flyable?Bert Van Bulck

Yes, why wouldn't it still fly? V2 is the single engine climb out speed.

This is by company SOP... for instance SWA doesn't use CLB derates at all, they believe you save more fuel by getting up higher faster.

HeyQuick question: using the derates, ever tried to cut one engine after V1? Is it still flyable?Bert Van Bulck

The derate/ATM takeoff still meets climb requirements. It's actually easier on an engine fail because there's less assymetric thrust.

Yes, why wouldn't it still fly? V2 is the single engine climb out speed.

I know it should still fly, but my question: have you tried it, (and how challenging was it)?Bert Van Bulck

Have a read of the post above yours. It is the same as any multiple engine aircraft except the 777 with TAC engaged. Derate will make the engine out easier to handle due to the reduced yaw.Not sure about SOP on the 737 but on the 744 selecting TOGA after an engine failure on a derated take off run could cause loss of control. You can cancel the assumed temp but never the derate.Regards