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UPS plane crashes near Louisville airport

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Re: UPS plane crashes near Louisville airport

#12
post #4

Earlier quoted context omitted.

The damage on the ground is scary to look at. I think the only silver lining here is that it was "just" a sparser industrial area and there weren't any homes. I'm really curious about what the investigation will reveal in a few months. This doesn't look like a "regular" engine fire from a bird strike or so, you would normally expect the flames to come out the back and not over the wing. And at least in theory the MD-…

> And at least in theory the MD-11 should be flyable with just two engines Flying with two engines and taking off without an engine in a loaded aircraft are two very different things. A lot more thrust is needed during takeoff than after.

Every multi-engine airliner is designed to be able to take off safely even if an engine fails at a critical moment. What might have happened in this case is that the mechanism of failure of one engine caused damaged or interfered with the operation of another engine (via smoke, debris, etc.), and taking off with two engines degraded is not part of the design criteria.

Re: UPS plane crashes near Louisville airport

#13

[flagged]

Likely no impact. It was departing with ~75 tonnes of fuel and suffered an unrecoverable mechanical failure. https://www.flightradar24.com/blog/flight-tracking-news/majo...

> suffered an unrecoverable mechanical failure

But was un-discoverable? Or un-preventable? Seems plane inspectors and safety-related roles were affected and have been furloughed:

> But for the people involved in inspecting our planes to ensure they follow Federal Aviation Administration safety standards, the situation is more complicated. While principal aviation inspectors were told to keep working, assistant-level inspectors and other support staff were sent home and then had to be recalled.

https://archive.ph/rEpTx

Re: UPS plane crashes near Louisville airport

#14

Earlier quoted context omitted.

Likely no impact. It was departing with ~75 tonnes of fuel and suffered an unrecoverable mechanical failure. https://www.flightradar24.com/blog/flight-tracking-news/majo...

> suffered an unrecoverable mechanical failure But was un-discoverable? Or un-preventable? Seems plane inspectors and safety-related roles were affected and have been furloughed: > But for the people involved in inspecting our planes to ensure they follow Federal Aviation Administration safety standards, the situation is more complicated. While principal aviation inspectors were told to keep working, assistant-level…

[deleted]

Re: UPS plane crashes near Louisville airport

#15
post #8
post #7

Earlier quoted context omitted.

I specifically remember watching a flight test doing an aggressive takeoff and having the voiceover say that aircraft (two engine) need to have enough power to take off full with one engine. And so can take off very steeply empty with two engines. Would that not also be the case for these planes?

Yes, planes are designed to be able to take off with a lost engine. Usually this will extend the roll a bit because the speeds are different for engine out operations. This isn't the first MD-11 with an engine out take off, 5 years ago a FedEx MD-11 took off with a failure in the left engine[1]. Slightly different case, obviously, but it's certainly something that is accounted for when designing planes. [1] https://w…

That being said, depending on how you lose the engine it can really mess up the takeoff; AA191 was lost when an engine detached from the plane on takeoff and took out part of the wing and hydraulic system with it. https://en.wikipedia.org/wiki/American_Airlines_Flight_191

Re: UPS plane crashes near Louisville airport

#18
post #7

Earlier quoted context omitted.

> And at least in theory the MD-11 should be flyable with just two engines Flying with two engines and taking off without an engine in a loaded aircraft are two very different things. A lot more thrust is needed during takeoff than after.

I specifically remember watching a flight test doing an aggressive takeoff and having the voiceover say that aircraft (two engine) need to have enough power to take off full with one engine. And so can take off very steeply empty with two engines. Would that not also be the case for these planes?

All planes are definitely capable of taking off safely even if they lose an engine at the worst time. Whatever happened here, I would be shocked if lack of thrust in the 2 remaining engines was a significant factor unless someone really screwed up the load calculations and they were overweight for conditions.

Re: UPS plane crashes near Louisville airport

#19
post #4

Earlier quoted context omitted.

The damage on the ground is scary to look at. I think the only silver lining here is that it was "just" a sparser industrial area and there weren't any homes. I'm really curious about what the investigation will reveal in a few months. This doesn't look like a "regular" engine fire from a bird strike or so, you would normally expect the flames to come out the back and not over the wing. And at least in theory the MD-…

> And at least in theory the MD-11 should be flyable with just two engines Flying with two engines and taking off without an engine in a loaded aircraft are two very different things. A lot more thrust is needed during takeoff than after.

Taking off with one engine inoperative (on a multi-engine aircraft, obviously - you aren't going to get anywhere with your only engine gone) is completely normal/within design parameters, albeit undesirable.

In fact, it being normal almost certainly contributed to the scale of this accident, since a single engine failure during the takeoff roll isn't considered enough of an emergency to reject the takeoff at high speed (past a certain speed, you only abort if the aircraft is literally unflyable - for everything else, you take the aircraft & emergency into the air and figure it out there). The crew wouldn't have had any way to know that one of their engines had not simply failed, but was straight-up gone with their wing on fire to boot.

Re: UPS plane crashes near Louisville airport

#20

Earlier quoted context omitted.

> And at least in theory the MD-11 should be flyable with just two engines Flying with two engines and taking off without an engine in a loaded aircraft are two very different things. A lot more thrust is needed during takeoff than after.

Taking off with one engine inoperative (on a multi-engine aircraft, obviously - you aren't going to get anywhere with your only engine gone) is completely normal/within design parameters, albeit undesirable. In fact, it being normal almost certainly contributed to the scale of this accident, since a single engine failure during the takeoff roll isn't considered enough of an emergency to reject the takeoff at high spe…

> The crew wouldn't have had any way to know that one of their engines had not simply failed, but was straight-up gone with their wing on fire to boot.

I don't know about the MD-11 itself, but other aircraft from that time period have sensors to detect and report overheat and fire in various parts of the aircraft, including engines and wings.

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