Perhaps, that instead of climbing in Managed, and waiting for the spd to build up at cruise altitude, when they levelled out - they decided to go for something like . . . 340kts, at a lower level in the climb, like here at thr red alt ok? and hold that spd 340kts until level at cruise, at which time - they would not have to accelerate. If all of that was below 10,000' they could have done that if ATC let them do it.
Say CRZ IAS330 TAS564 = JSA -56.6 (default)+15=- 45.6 deg C = then the crew have set themself up nicely for Mach .81 cruise . . ? see? You also cover more ground in the climb, you also climb more readily, and you also use more fuel, but, you save on time to accel = 0
you save on accel fuel at alt = 0 Hence the sound you heard -
If you can work out how much fuel you burn climbing up to FL330 at 340kts and how much fuel you`ll save AT FL330 already doing 340ktsIAS plus the fuel thus saved in the performance climb - then maybe it could be worth it - but all in all, they would be further, faster, and faster sooner.
Last edited by Natstrackalpha; 10th October 2013 at 00:09.