Originally Posted by
Ave8tor218
OR...
Master Caution beeper for the AIRSPEED LOW EICAS triggering (28:28 on liveATC), indicating they were below min maneuver speed. Then when he’s saying “Stall Stall Stall Stall Stall” the Master Caution beeper goes off again at 28:40 followed by the most likely AP disconnect triggering the Master Warning siren at 28:41.
Going to NGO I’d guess they departed with somewhere in the 740-766,000 TOW range with Flaps 15 based on my experience for similar range flights. The min flap maneuver to flap overspeed spread at those weights for Flaps 1/5 is about 3 knots. I’d bet money they retracted the flaps with not enough of an upward airspeed trend vector, while still 10-15 knots below min maneuver, with the autopilot on
Yeah, listening to the recording again, they were already in the stall before they would have had a chance to do what I suggested.
It's possible they could have messed up with the clean up maybe throwing in some bank with the power coming back for level off, but the speed issue you mention doesn't make sense.
At about a 766 MTOGW departure, Vref is about 185 KIAS and clean maneuvering speed is usually about 265 KIAS (Vref 185 + 80). At 265 you're well above the red "zipper" and usually sitting just above the amber foot.
Min maneuvering speed for flaps 1 is Vref+60 - 245 KIAS with a limit speed for flaps 1 of 265 KIAS
MMS for flaps 5 is Vref+40 - 225 KIAS with a limit speed of 245 KIAS
All those speeds give the standard 1.3G margin.
20 knot spread in both cases. I don't know where you're getting the 3 knot thing. You can fly very comfortably with flaps 1 or 5 after a Max GW takeoff at 245 or 225 and still be 20 knots away from over-speeding the flaps.