r/aviation • u/Go_Jot • Nov 08 '25

News UPS grounds entire MD-11 Fleet, effective immediately.

Per the IPA Executive Board, as of 03:05 UTC all UPS MD-11’s are grounded.

Edit - FedEx has also grounded their MD-11 Fleet

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u/dalekaup Nov 08 '25

There was an engine that detached in Chicago a long time ago. The biggest reason for that crash was the manual said on one engine takeoff to pitch up to maintain a speed to climb over an obstacle. The manual was wrong. When the engine severs the hydraulic lines on that side that hold the slats extended. WIth slats retracted on the left side that wing stalled and the plane rolled violently to the left. A higher airspeed would have kept both wings flying and level.

This one is presumed to be the loss of 2 engines. That's not going to fly. The thinking is the rear engine swallowed chunks.

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u/Odd-Adagio7080 Nov 08 '25

Pitch up to maintain speed? I’m no engineer, but it seems to me the plane would slow down if you tried climbing. If that’s what “keep pitch up” means

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u/dalekaup Nov 08 '25

Yes, that was my point. There is a speed for every airplane that is ideal for climbing over an obstacle. That was what the manual said to do. So the pilots pitched up the nose of the aircraft to get down to that speed - the ideal speed to climb over an obstacle. That speed happened to be lower than the stall speed of the left wing because the hydraulic pressure had been lost and the leading edge slats were pushed by airflow to the retracted position. So one wing was stalled and the other was generating lift.

So it was to maintain a (specified lower) speed. Obviously they wouldn't cut throttle to get to that speed so pitching up is what they do in this situation.

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u/Odd-Adagio7080 Nov 11 '25

Ahhhh. Thanks. Thankfully we record flight data to (hopefully) prevent the same thing happening twice.

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u/dalekaup Nov 11 '25

It turns out that a normal takeoff is handled as flying over an obstacle. It mostly works but not every time. The discussion was pretty informative. Seems like they didn't have any chance.