When comparing a high-speed, cruise-power descent against a cruise-speed, reduced-power descent, there are a surprisingly large number of variables in the equation, all pulling in different directions.
On the one hand, descending at cruise power will guarantee a higher airspeed, but on the other hand it comes at the cost of a higher fuel burn. However, a higher airspeed will reduce the amount of time in the air, and thus overall fuel cost, right? What about true airspeed? True airspeeds are highest at cruise altitudes, and decrease approximately two-percent per thousand feet during the descent, which throws in an another dimension. So which method is truly more efficient?
