This crash is very strange to me. No flaps (even if hydraulics fail, there’s electrical backup), no gear (there’s gravity extension backup), landed way down the runway (9000’ should have been plenty, gear up landing has been done in shorter distances)… what happened?
My guess at the moment: bird strike made the pilots panic, they didn’t ensure the plane was in the correct configuration when attempting the second landing, and tried to put it down soft and ended up going long?
What do I know though, I’m not a pilot, just a fan of disasters and flight simulation. Guess I’ll have to see what blancolirio has to say.
Edit: Juan Browne, aka Blancolirio on YouTube finally posted a video on this, probably some of the best insight we’ll get at this early stage.
I don’t think whatever electrical backup has enough power to deploy flaps at landing or near landing speeds.
737 NG alt flaps work up to 230 knots, well above landing speed. Landing with hydraulics out is the primary function of the alt flaps system. It’s really slow, however, so flaps 15 is typically the most they use.
I didn’t find the speed rating for the alt flaps, but I was able to verify that it is an electrical system backup
There’s a placard in the cockpit with flap speed limits.
Definitely a strange crash, although it sounds like there was some mechanical stuff going on as a result of multiple bird strikes on the previous approach.
Lots of airports around the world have EMAS which is designed to stop an airplane in this situation. Unfortunately this airport has a concrete wall instead. Google maps has it labeled as “Walls of death”, although I don’t know if that was recently added or if they’ve had that nickname for a while. https://maps.app.goo.gl/eX9Fp9RXeVkRB94L9
EMAS requires a certain pressure to break through the surface. It’s designed for gear down overruns, not belly landings. I don’t think it’d do much if it were installed in this case.
From skybrary.aero:
Additional assumptions for all designs are that:
- an aircraft is still attempting to stop as the runway is exited
- reverse thrust / reverse pitch is not being used as the runway is exited
- the surface area leading to the EMAS bed has poor braking characteristics
- there is minimal or no structural damage to the landing gear
- there is no aircraft braking or use of reverse thrust / reverse pitch once an aircraft enters the EMAS
That penultimate point is key. It’s not designed for a no gear landing, or even damaged gear landing. It adds friction by the gear sinking into the materials.
Typically yeah, but I think there was likely enough weight on the engine cowls to make the engines dig in to EMAS. I wonder if it has ever been tested.
Certainly wouldn’t have hurt, but I don’t think it would have done that much.
From skybrary:
Most installations to date have used a maximum 70 knots bed-entry speed.
…and thats with gear down. I believe the Jeju plane was doing something like 130+ kts off the end of the runway.
It’s not a “strange” crash. It’s yet another Boeing crash.
But capitalist media isn’t going to put that in the headline.
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According to this article, there does not appear to be an attack at play.
