Byron is wrong. Not by much. But he's still wrong My premise is that high speed descents are inefficient because parasitic drag increases by the square of the speed. 150kias is a 56% increase in drag over 120kias. That extra speed in the high speed descent comes at the cost of wasting fuel that is burned off into drag. I tried to carve out some examples off the top of my head based on numbers I'm used to seeing. Granted I didn't test record these numbers from tests but I've got enough 201 t