Joshilini - the report says the Captain retracted the flaps in an attempt to reduce drag.
The stall speed reduction from flaps 30 to flaps 25 is 2 kts. That requires a higher AOA to achieve the same amount of lift. I have no idea, and I doubt very many, if any, non Boeing test pilots know if reducing the flaps from 30 to 25 is a net reduction in total drag. I don't know the answer. I'll await the results of the investigation. However, based on the resulting AOA increase I tend to doubt that total drag was reduced.
If you have time you can test this in the sim. Set up a steady flight condition, fly Vref -20, and retract the flaps from 30 to 25. Fuel flow goes up, you're fighting more drag. Fuel flow goes down, total drag is less. I'd recommend turning level flight to increase the power, thereby making it easier to see any differences in power required.
Last edited by misd-agin; 30th Dec 2009 at 19:37.
Reason: clarification