US Airways Jet crashes in Hudson River

[T.Neo]

The A320 even has a "bomb on board" checklist

Does the A320 have a crying kid who didn't get a window seat checklist?

 

[Urwumpe]

The A320 even has a "bomb on board" checklist

Now, that would be something I want to read. :lol:

 

[Zatnikitelman]

The A320 can't dump fuel according to Wikipedia. In fact, I found that most smaller planes can't dump their fuel because their landing weights aren't more than 105% more than their takeoff weights. So even with a full tank of fuel, the smaller planes can land just as safe as if they had burned up their fuel enroute. Of course, safely, and reusably are two different things and airfract that land overweight usually have a special inspection done.

 

[T.Neo]

Now, that would be something I want to read. :lol:

Agreed.

Imaginary excerpt from checklist:
-Step 1:Find the bomb
-Step2: Open the bomb casing
-Step3:Cut the blue wire
-Step4:If you haven't been blown to simthereens, cut the red wire.
:rofl:

 

[Zatnikitelman]

Or if your name happens to be Mitchell, and you meet another Mitchell, then it's "cut the green one!" :rofl:

 

[Moonwalker]

The A320 can't dump fuel according to Wikipedia. In fact, I found that most smaller planes can't dump their fuel because their landing weights aren't more than 105% more than their takeoff weights.

Yes, I totally missed that point (because I'm currently involved in Boeing 727 stuff, which includes fuel dump for that aircraft type, and for the A320 I just looked into the check lists, instead just to remember that fuel dumping is not existent at all ^^). Neither the A318 to A321, nor any Boeing 737 type is equipped with a fuel dumping system.

Now, that would be something I want to read. :lol:

Agreed.

Imaginary excerpt from checklist:
-Step 1:Find the bomb
-Step2: Open the bomb casing
-Step3:Cut the blue wire
-Step4:If you haven't been blown to simthereens, cut the red wire.
:rofl:

:lol:

But it's actually no joke. Have a look:

 

[mjessick]

> It's counter-intuitive that ditching heavy might be good,

Remember, the amount of energy you have to dissipate in the slowest possible landing is proportional to mass squared ( E ~ m^2 )

 

[Andy44]

Yes, but it's okay to take a longer time and distance to dissipate energy in a water landing; your main concern is keeping the aircraft intact and afloat long enough to get everybody out. In the jetliner ditchings I've seen video of, they roll over and the wings rip off. In this case that didn't happen, and it's possible that fuel mass in the wings may have helped. It's just Cairan's hypothesis at this point, but I think it's an interesting one.

About the bomb checklist, I figured it would look something like this:

 

[Moonwalker]

In the jetliner ditchings I've seen video of, they roll over and the wings rip off. In this case that didn't happen, and it's possible that fuel mass in the wings may have helped.

I think the most important factor is the condition of the water surface. If the sea is rough and you don't touch the surface with wings aligned horizontally, like it was the case for the Ethiopian Airlines Flight 961 you obviously refer to (Boeing 767), you have almost no chance not to destroy the airplane. The Hudons river just was calm enough and I think that the A320 came in perfectly aligned, which the Ethiopian Airlines 767 did not.

 

[Cairan]

Of course the surface conditions are vital, but I still think the full wings contributed a lot to the happy ending last week. As it was pointed, it ends up having more energy to dissipate to stop, but the fluid nature of the fuel in the wings helps to "push back" against the pressure of the water imparted on the forward structural elements of the wings, such as the spars. The fact that the wing has to "hold back" a given mass of fuel which naturally wants to go forward and "drag" the wing with it while the plane is decelerating actually helps reduce a lot the bending loads on the wing spars and the wing box.

Wings and wing boxes are designed to support incredible loads in the lift vector, but not so much in the longitudinal axis. For the A320 familly, with a maximum take-off weight of ~80 tons, each wing has to deal with quite a lot of torque vertically, but in the longitudinal axis, even with both engines at max take-off power, you'd get about only a 1/3 G, maybe even less. Even if you take the plane with barely enough fuel for a ground test at max thrust, you'd get only 3/4 G. A kick in the pants, but still nothing compared to a ditching...

Here's a quick calculation... With 10 tons of fuel in a wing, decelerating it at 1 G would result in a force about the same as the thrust from the engine attached to the same wing at takeoff power, ~100kN.

 

[T.Neo]

LOL. :lol:

@ Moonwalker: That is interesting, notably the part "DO NOT OPEN THE BOMB DO NOT CUT WIRES". I'll remember to be on the lookout for any crew members asking for EOD personnel.

 

[Urwumpe]

I think the most important factor is the condition of the water surface. If the sea is rough and you don't touch the surface with wings aligned horizontally, like it was the case for the Ethiopian Airlines Flight 961 you obviously refer to (Boeing 767), you have almost no chance not to destroy the airplane. The Hudons river just was calm enough and I think that the A320 came in perfectly aligned, which the Ethiopian Airlines 767 did not.

In case of flight 961, the roll was more the problem, also the pilot had the stupid idea to land parallel to the waves. if at all, you should land with the waves.

Also, the 961 landed more flat, which also helped in it's destruction.

What killed more people then, was the panic idea to blow up the life vests in flight, which trapped the people inside the cabin, unable to open the seat belts.

 

[T.Neo]

What killed more people then, was the panic idea to blow up the life vests in flight, which trapped the people inside the cabin, unable to open the seat belts.

That bugs me. It seems the instinctual thing to do, I'd do it if I didn't know better.

 

[Hielor]

That bugs me. It seems the instinctual thing to do, I'd do it if I didn't know better.

This is why you should actually listen to the safety speech they give you, in which they specifically say to not blow up your life vest until you're just about to leave the aircraft.

This recent ditching also shows why they do the safety briefing before takeoff, while taxiing.

 

[T.Neo]

This is why you should actually listen to the safety speech they give you, in which they specifically say to not blow up your life vest until you're just about to leave the aircraft.

Safety speech? What safety speech? I don't remeber hearing any "safety speech".

 

[Urwumpe]

That bugs me. It seems the instinctual thing to do, I'd do it if I didn't know better.

Yes, and that is a wrong instinct. And if you would have experimented with life vests you would know, that this just hinders you.

 

[T.Neo]

Yes, and that is a wrong instinct. And if you would have experimented with life vests you would know, that this just hinders you.

Look, I've experimented with water, swimming etc. And it is very hard to pull say, a 2L cooldrink bottle underwater if it is full of air. So I can understand how much of a hindrance an inflated life jacket must be. I'm saying, from an uneducated, panicked veiw, one might imagine that inflating the jacket before the crash would be a better idea. But it isn't

So, to fix this, instead of going through the safety speech in a sing-song and monotonous manner, they should emphasise certain points, "Do not inflate the life jacket until you are outside the cabin and clear of the aircraft structure!", etc.

 

[Moonwalker]

In case of flight 961, the roll was more the problem, also the pilot had the stupid idea to land parallel to the waves. if at all, you should land with the waves.

Well, the pilot had no stupid idea, he just had no different choice combined with the hijackers in his neck. His 767 was out of fuel and both engines already had failed. There was no option to prepare the landing any better. And landing with the waves would have resulted in a crash into the beach and the people there, since the airplane was just a very few hundred meters away from the beach anyway.

What really caused the crash on the water was the high speed and that the left wing dived into the water first. The rough water surface and the direction of waves did the rest to the airplane structure, regardless of the life vest usage.

 

[C3PO]

In case of flight 961, the roll was more the problem, also the pilot had the stupid idea to land parallel to the waves. if at all, you should land with the waves.

Also, the 961 landed more flat, which also helped in it's destruction.

What killed more people then, was the panic idea to blow up the life vests in flight, which trapped the people inside the cabin, unable to open the seat belts.

I think you can make a case for both options. In the Hudson river crash not wearing an inflated vest is the best way to go.
But if the plane breaks apart like EA 961, an inflated vest could save your life. I remember an interview with a passenger on EA 961 who said that he regained consciousness floating in the water.

 

[Urwumpe]

I think you can make a case for both options. In the Hudson river crash not wearing an inflated vest is the best way to go.
But if the plane breaks apart like EA 961, an inflated vest could save your life. I remember an interview with a passenger on EA 961 who said that he regained consciousness floating in the water.

But how many people will be saved that way? If you are catapulted out of the plane, you are very likely already in a bad situation. It would be better if vests would inflate automatically in case of water contact, but I can understand a manual solution.