Tom, I wholeheartedly agree with your logic and reasoning. You are not mad after all! Flap retraction should be speed related andspeed related only.
The starting point for all this must be obstacle clearance. The basic requirement is to ensure you have it. OEM’s provide information in their AFM’s in the forms of procedures and performancei nformation in order for you to be able to calculate it in advance. After you start the takeoff, however, your actual performance is what matters. There have been a few comments about becoming a test pilot, not so. The departurehas the gradients required and hence you know the rate of climb required for your speed. If you’re making that or better then you are meeting the climb requirements regardless of whether your aircraft has a graph to tell you in advance. If you are qualified on a type you know if you are flying an aircraft with loads of excess performance on one that is very limited. I have flown aircraft have sufficient excess performance available that an early flap retraction is possible and considered normal. I have also flown aircraft that are on the bones of their arse for climb performance and no-one in their right mind would start accelerating early.
In the case mentioned early on of setting 15 degrees nose upand letting the aircraft accelerate to V2+50 I can’t see any sound reason forthis choice. I can see why a pilot maywish to maintain V2+10 (or whatever your aircraft uses) until acceleration altitude but if you are limiting yourself to a deck angle and accelerating in the climb to well above that speed then you have the performance to retract theflaps. If you have thrust to be able to accelerate whilst maintaining your required climb gradient and you reach min flap retraction speeds then there is no reason not to retract. In fact you will be in a better placed if an engine fails at that point. If, however, you are in a more performance limited aircraft and you need a level acceleration segment then you can’t just throw that in whenever you feel like it.
Last edited by Roger Greendeck; 21st Nov 2012 at 00:50.