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downwind
28th Sep 2005, 14:21
Guys,

Just wondering if you do a high speed clb/des does it save fuel over the 250 knots below 10000? (if you use the FMC CLB/DES speeds plugged in with VNAV?

Thanks
DW.

Old Smokey
30th Sep 2005, 14:42
At any time that ANY aircrfaft, not just B737, conducts a climb at less than, or more than, optimum range climb speed you will consume more fuel. This speed is typically slightly higher than best Rate of climb speed, and significantly higher than the best gradient speed.

Our company policy is to apply the 250 KIAS limit only to 5000 feet (except of course at those airports where it is required to a higher level), and for the B777, accelerating to best Econ Climb speed (typically 320 KIAS) as soon as possible after 5000 feet saves about 400 Kg in climb fuel.

At the end of the day, it depends how far removed from 250 KIAS lies your best Econ Climb speed. If it's fairly close to 250 KIAS, it won't make a lot of difference.

Regards,

Old Smokey