Why stay up at altitude longer with cruise thrust when you can be in a idle denscent? Sure specific fuel consumption will rise as you descend, but its still more fuel economic if you can fly with the throttles closed all the way from TOD in to 3-4 miles final. The only reason to stay up longer and descend at a higher speed (steeper descent gradient) would be if you have a high operating cost as compared to the fuel price.Caveman said:Okay, I'l bite. What's wrong with using speed brakes? Stay high longer to save fuel and then rocket on down at the last minute. What's the big deal? Is this some kind of ol' timer traditional thing? If I'm not sopposed to use them why did they give 'em to me in the first place?
But of course the speed brakes are there for a reason, use them if you have to. I try to use them as little as possible because evertime i use them i "waiste" energy, which normally means you have to spool up the engines earlier on the approach and burn more fuel. But if ATC keeps you high, or if you get a more direct route while in the descent, you will have to use them. But then again the only real speed brake on the 73 is the gear.
Just basic energy management.