Tarq57 - "The only option the crew seemed to have was to reduce excessive drag (reducing flap a bit) and maintain an airspeed that would allow a controllable impact. "
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Are you a professional pilot?
Aircraft have best glide speeds. Typically approach speeds are slightly slower than L/D to allow a slighter higher power setting. Slowing below best glide speed shortens your gliding distance(we'll skip the arguement about min sink with tailwind...).
"Reducing excess drag" - I've yet to see an official statement stating if total drag decreased or increased, and it's impact on gliding distance, by selecting Flaps 25 instead of leaving them at Flaps 30.
The flight was at Vref 135 kts with Flaps 30.
If slowed to 118 kts Flaps 30.
Flaps 25 were selected.
It slowed to 108 kts Flaps 25.
At 108 kts it couldn't slow anymore due to AOA protection from the FBW flight control system. So the sink rate increased. At that point everyone was along for the ride.
The arguement is 135 kts Flaps 30 gliding performance better than 118 kts Flaps 25? I don't know the answer for a fact. However, based on all my training, civilian, military, corporate, airline, to include heavy jet flying, fighters, and gliding, I'm inclined to believe Vref Flaps 30 is the correct choice. Unfortunately that is a scary view out the front windshield. I've done it in the simulator, which is a long way from real life, and it wasn't pleasent.
Every professional pilot knows that gliding performance was better at 118 kts Flaps 25 than it was at the AOA limit with 108 kts. Higher and higher AOA does not improve your gliding performance when you are slower than L/D.
The flight crew took one action that the aircraft would not have done by itself, that is the retraction of flaps 30 to flaps 25. Other than that there's a very good chance the aircraft would have hit in the exact same location if there were no pilots.
Last edited by misd-agin; 11th Jan 2010 at 03:42.
Reason: clarification