Originally Posted by
Trip7
I don't get your point. If you were paying the fuel bill and REALLY wanted to save money you'd use the speedbrake every flight because you'd stay high as long as you possibly can before making a steep 4 or 5 degree descent at flight idle max speedbrakes. That would be the most efficient way to fly the plane but would be dumb to do since you have used up all possible methods to shed energy for any unanticipated events ( increased tailwind, ATC speed reduction, crossing restriction etc)
For me 200 speedbrake use has increased drastically because we reduced our flap 8 limitation to 200kts from 215kts due to increased flap failures. When the 200s 1st came out the factory limitation was 230kts
Trip, it's been proven that a prolonged idle descent is more efficient than s slam dunk 5 degree/idle/max speedbrakes. The method you suggested only gets you a few extra minutes at top of cruise and the reduced time at idle negates what fuel you saved by staying high longer. It is also not as friendly when it comes to passenger comfort. Obviously there are times when we need to use speedbrakes but you are missing my point that with better planning we can minimize their usage and save fuel.