I'm more surprised the wing rupture didn't cause a fire/explosion because this is where most of the fuel is stored.
Hell even in a crash landing like this you want the plane to stay upright and stable.
They know how much peak load is supposed to be for the airframe, then they go well beyond it to see how the plane fails. Generally you want the wings to break not the fuselage.
You can in a lot of situations land a plane with 1.5 wings. But once the spine cracks you’re just a ballistic object.
I used to work at Boeing on the 757 stabilizer trim system. There's the design group and the stress group. I was in the design group, the stress group double checks the design work.
One day the stress group called me on the carpet, and asked me why my designs consistently just barely exceeded 150%. I said I started with the ultimate load, and worked backwards to size the part. The stress groups said they prefered designs to be 10% over the ultimate load. I replied that I designed to the requirements, as adding 10% makes the airplane overweight. If they didn't like the design requirements, change them.
They grumbled, but I got my way :-/
A few months later, they offered me a position on the stress group. It was a nice compliment, as they normally required a masters' degree and I only had a bachelors. I told them I was honored by the offer, but my heart was in design.
Some time later, my parts were put on the torture rack to see if they passed the ultimate load test. All of them passed on the first try.
I also had the privilege in being mentored by some really fine engineers at Boeing, such as J Burton Berlin and Erwin Schweizer.
Am I proud of that? Yes. I love flying in the 757. Best airplane Boeing ever made. Whenever I fly in them I chat a bit with the flight crew, and they love it, too.
Have you shared your thoughts on MCAS? I feel like there are a lot of potential lessons that got missed for all the noise.
The 737 is an electric drive, with a manual backup. The 757 is a scaled down version of the 747's dual hydraulic drive, no manual backup.
More efficient wings and engines obsoleted the 757.
Thanks for making the D programming language. If it did not insist on a GC and had a robust and stable GC-free stdlib, I believe it could have conquered the world.
BTW, the GC makes the compile time function execution sweet and easy.
If anyone is wondering, this is always the correct answer when there’s a disagreement between reality and the specification and you’re following the spec.
I don't know enough about the details of the CRJ-900 to say for certain, but in general aerospace engineering does include considerations of this sort, where if a component breaks off you want to ensure that it separates in a specific way.
from an Admiral Cloudberg article [0] about El-Al 1862 [1]:
> The Boeing 747 engine pylon is attached to the wing by four fittings: one at the front, one in the back, and two in the middle (or midspar). Each of these fittings consists of a wing-mounted male lug and a pylon-mounted female lug, which are connected by a fuse pin. The four fuse pins are the weakest part of the pylon, but this is by design. Every airplane system and structure contains planned failure sequences which work to minimize damage in the event of an overload. In the case of the 747’s engine pylons, the fuse pins were designed to fail at a lower load threshold than the fittings themselves, ensuring that if the engine is torn off the wing — perhaps due to extreme turbulence, or a gear-up landing — the fuse pins will fail first, causing the engine to separate cleanly without ripping open the fuel tanks located directly above it. In theory, this should allow an engine to break off upon reaching its design load limit without starting a fire or otherwise compromising the plane’s ability to fly.
0: https://admiralcloudberg.medium.com/concrete-and-fire-the-cr...
The integrity of the wings is a function that supersedes just about every other possible thing on a plane. You can safely land without any engines. You can safely land without hydraulics. You can safely land without gear. Without wings, a plane is a brick.
The engines are built to rip off cleanly, because when they don't, they have caused https://en.wikipedia.org/wiki/American_Airlines_Flight_191 and https://en.wikipedia.org/wiki/El_Al_Flight_1862 which were fairly serious and catastrophic accidents at least partially caused by the engines tearing off and damaging the wing in such a serious manner as to cause a stall and crash. The wings stayed on the aircraft in both instances. Interestingly, both accidents were caused by those same sheer pins being damaged in minor and unpredicted ways.
I highly doubt the wing is DESIGNED to cleanly separate. Planes are just very not rigid for something going such a high speed, and so tend to turn into confetti when faced with a harder surface, like a runway or a concrete building. Usually the only parts that survive serious crashes are the landing gear struts.
The fuselage couldn’t take a fraction of the stress the wings are designed to endure.
https://simpleflying.com/minimum-fuel-requirements-definitio...
If an aircraft is anticipated to land with fuel for 30 minutes or less they must make a mayday call, and there's an incident report to fill in.
Yes they want to land with as little fuel as possible, but regulations require them to carry more because we know what happens when you let airlines carry less.
It isn't on any aircraft I've heard of. Only the engines have "fuses" which allow an engine to rip itself off without taking the wing with it.
The wing root is the strongest part of the airplane (because that is where the maximum forces are).
If the engine loses a fan blade, it will vibrate violently and it's probably better to lose the engine.
I don't know about the other two things you mention. Maybe it's a newer feature than my time :-/
That's the idea with a fan blade loss, they didn't want to just drop an engine in that case so the centering mechanism on the turbine has an intentionally weaker part is designed to snap off to allow the spinning turbine to recenter itself as opposed to vibrating the whole structure off and causing more damage.
The gear thing is to prevent puncturing the fuel tanks in the wings on a hard landing. It's preferable to snap off the gear, otherwise leaking fuel has a good chance of it immediately igniting.
But yes, in a full size passenger aircraft I would expect the specification for wings falling off to say "avoid"
I’m guessing wind, ice, or something else moved the plane off the centerline and into a crab, it hooked a wheel off the pavement, and cartwheeled. 100% conjecture at this point, just seems like a possible chain of events.
Edit: listing to the ATC audio I think they said gusts in the 30s (man do they ever speak fast and mumble! Enunciate damn it! Unique New York), which is markedly slower than what the Apple Weather app reported for Pearson.
33kt/hr * 1.15mi/kt * 1.609km/mi ~= 61km/hr.
The weather app was right. Just different units.
https://people.com/new-video-dc-plane-crash-shows-final-seco... was an airport camera, IIRC.
It looks like the video is taken from https://www.youtube.com/watch?v=VaIL2UOX4ss - it says it's "Kennedy Center Cam", it also wobbles, but that's probably wind. But yeah, it's not an airport camera.
https://www.reddit.com/r/Damnthatsinteresting/comments/1isa8...
Does nobody have a sense for the dramatic?
https://cdn.shopify.com/s/files/1/2604/4866/files/5aedc13c-3...
It's likely not a morbid curiosity here, especially since noone died AFAIK, but genuine technical curiosity so he can see what happened, and perhaps educate us readers.
Back in my 757 days Boeing ran individual wires for everything. I suggested using a bus to save weight and improve reliability. I just got blank looks in response. Modern cars use a bus now, and probably the airliners do, but I have no direct knowledge of it.
The thing about cameras, though, is you can buy an HD dash cam for $100 that records in a loop. Buy it, plug it in, and point it at the runway. It doesn't need anything beyond a wall socket.
If I was an ATC sitting in the tower, I'd probably just install one myself.
This kind of footage of an aviation accident should not be left to chance.
You seem to know a lot about him, which indicates you bravely made a throwaway to write this drivel. Please seek help. In the meantime, I do hope our lone mod IP bans such low effort members.
I recommend using actual quotes when quoting. Otherwise people might think you're just making things up.
I think parent was saying the roll was along the planes' length rather than tail-over-nose, the latter usually result in the aircraft breaking up as the torque will be really high.
- longitudinal axis: roll, controlled by ailerons.
- vertical axis: yaw, controlled by rudder.
- lateral axis (through the wings): pitch, controlled by elevators.
In larger aircraft that do have the ability to dump fuel, the reason is to make the airplane lighter so it does not have do an overweight landing and the subsequent high-cost overweight landing inspection. It is not done to reduce the probability of a post-crash fire.