PPRuNe Forums - View Single Post - Acceleration check procedure for liners
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Old 14th Aug 2019, 16:12
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F-16GUY
 
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gearlever and FlightDetent, thanks for the explanation. So basically flex is another word for reduced power T/O.

Disregarding climb performance requirements or wrong configuration situations, as the power setting is fixed (but reduced), it should be fairly simple to calculate an acceleration check speed after a certain distance, if the weight, configuration and atmospheric conditions are known. I understand the fact that if the numbers put into the calculation are wrong, the acceleration check speed would be wrong to, but the entire point of this check was to confirm that the aircraft is performing as expected. So putting a lower than actual weight into the equation, or having an engine problem, will reveal itself to the pilots at an early stage, by the fact that the aircraft is not meeting the expected performance.

I don't buy the the comment by small cog and vilas, that the T/O phase is too "high workload" for a two man crew, that there won't be time to perform a quick "how gets it" with the acceleration check. Especially since a reduced power T/O gives the crew much more time between brakes release and T/O. If the vis is pure, surly the distance used can be derived from the systems (INU or GPS).

I acknowledge the fact that liner pilots take off from many different airfields, under many different conditions with varying loads and varying power settings , but I think that simplicity is the key for an acceleration check.

One more question: When punching all the numbers into the FMS, to get the flex power setting, doesn't the system then also display the required distance from brakes release to rotation or T/O, so that the crew can do a sanity check whether the runway a head will suffice?
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