On types I have flown, we would always be able to accelerate to cruise Mach at any altitude, (provided we are not above the ceiling for the weight), so I usually go as high as the book says we can (unless we can ride a jetstream up the chuff lower down).
It leads to a huge fuel saving (agreed, no-one seems to care about that), the TAS is the same as lower down in the stratosphere, its smoother, and on the legs we do, it sometimes makes the difference between a fuel stop and not (which everyone cares about).
But if I'm right in thinking you are on the Hawker, I do believe that struggles well before its ceiling?
Last edited by Joe le Taxi; 2nd Jan 2013 at 10:54.