Question for PILOTS, what are the requirements for a safe water landing?

[shireen]

I'm guessing that angle of attack and velocity are critical factors.

How buoyant is a large aircraft, like the UA airbus in the Hudson?

Can you walk us through what the pilots and cabin crew are trained to do?

[Cleita]

1. Back in the forties and fifties when my family few a lot, it seemed like we

traveled over bodies of water a lot. My dad explained that there was a better chance of survival if the airplane landed on water. Of course, these were prop planes. Commercial jets weren't in use then. I don't know if the same reasoning applies to jets.

[av8rdave]

There are a lot of unknowns with that, because

there have been relatively few cases where a large aircraft has survived a water impact completely intact. Our manuals state you can count on roughly 10 minutes of buoyancy after water landing if the aircraft is intact. As far as a "safe" water landing goes, the main issue is the degree of control that still exists. Also sink rate at impact, pilot visibility, forward speed, prevailing winds and water surface condition are all factors.

[GodlessBiker]

2. Requirement No. 1: Lots of water.

[Cessna Invesco Palin]

3. Requirement #2: Balls (or ovaries or whatever) of fucking steel. n/t

[kenny blankenship]

10. Check for water hardness

http://www.h2okits.com/site/1286521/product/PFP - Hardness


It's also best if ground temperatures are above 32F

[malaise]

13. and better a river than the ocean

water is calmer.

[MajorChode]

4. There are a number of factors

On a situation like the one that happened today, there's really not too many options. You're going in the drink and you don't have time to figure out which way the waves are going or anything like that.

The best thing you can do is try and keep the plane from stalling and to maintain enough airspeed to flare the plane a bit before touchdown so that you ride it out as far as possible to keep the G forces at a minimum.

How buoyant the plane is depends on how much fuel it's carrying.

[BR_Parkway]

5. Take a deep breath.....

[BrklynLiberal]

6. Pontoons.? Luckily in this case, the plane was still ascending so it had not reached max velocity.

[Captain Needa]

7. Requirement #3: Tons of luck

Even with relatively small aircraft (i.e.: Airbus A320), minimum landing speed is 140 knots. That gives you a shitload of kinetic energy when water landing. Here comes the pilot's ability to minimize impact, because at very low speed the aircraft stalls, so you don't want to crash it against the water because it behaves like a concrete wall. The higher the attack angle, the lower speed the aircraft can fly without stalling, but on the other side if the flying speed decreases, you reach the critical point very fast and the plane immediately stops flying. What you want to do is negotiate with every factor and slide into water, of course that's theory.

Edit for typo.

[Hawkowl]

15. Relatively small?

Dude. An airbus 320 weighs over 150,000 pounds. What's your definition of large?

[Statistical]

8. Boyancy is the last concern. It could have been 100% fatality event very easily

I have private pilot license but nothing like those big birds I fly single and dual prop aircraft.

The golden rule of aircraft is:
You can trade speed for altitude, or altitude for speed. You can trade either for time. If you are out of speed, and out of altitude then you are out of time

Once the plane lost both engines it was literally a matter of a minute or two before it was on the ground. Period.

So the pilot did an AMAZING JOB.

Losing one engine, the plane can turn around and make an emergency landing. If you lose both you don't have that luxury.
To lose both shortly after takeoff means the plane had little speed and little altitude.
Remember speed->time altitude->time. Having little of each gives the pilot even less options.

Once he got it over the water the job wasn't done yet. The plane was moving about 150-200mph as it touched the water.

The pilot HAS TO keep the wings level. The plane will hit off center and have a tendency to dip one wing.
If the pilot can't correct that or overcorrects the wing will hit the water and at that speed it will rip off.

When the wing rips off it will destroy the airframe. The plane will break into fragments and everyone will die.

The pilot did the three things you MUST DO to survive
1) got control of aircraft
2) quickly determine location to land, and flight path
3) landed the aircraft while keeping it level

If you do all three friction will slow the plane to stop. It will sink eventually but the sinking is the least of your worries.

[FightingIrish]

9. When I flew in a Navy turboprop abouth that same size,

we did ditching drills but no one was convinced that ditching the plane was survivable. Apparently it is and someone actually succeed in ditching one in 1995. Here's great account from the pilot's perspective.

http://www.vpnavy.org/vp47ditch.html

The crew of the US Air plane did an incredible job.

[TahitiNut]

11. "The crew of the US Air plane did an incredible job." Amen!

Everyone should remember this when the airlines try (again) to cut their pay/benefits. An extra dollar off on a ticket ain't worth giving up that kind of professionalism.

Remember also: They're UNIONIZED!!

[malaise]

12. Damn straight Skippy!!

Amazing.

[Hawkowl]

14. Very tough

The max altitude the airplane achieved was 3200 feet. This means the plane only has about 9 miles of travel left to work with. Assuming you want everything stabilized at about 500 feet minimum, that means about 7 miles to get your shit together. Or averaging 180 mph, 3 miles per minute, you've got a little over two minutes. Two minutes sounds quick but we are trained to do a helluvalot in two minutes.

So, the pilot flying (usually the captain at this stage of emergency) maintains control of the aircraft by maintaining airspeed while the co-pilot troubleshoots by pulling out the emergency manual and coordinates with the flight attendants to brief them on the imminent ditching.

While flying the airplane you have to pick a spot to put it down. Ironically enough, a major urban area such as NYC makes it easy. You only have one choice if you're not near enough a runway, the water! Calm water was very helpful in keeping the plane from breaking apart. Also the fact that no boats or bridges or power lines were in the way wasn't just luck; the pilot had to pick the spot very carefully.

So once you've determined you can't restart an engine, or you've run out of time, then you are committed and the flying pilot sets up as closely as possible to a normal approach and landing. The non-flying pilot switches from troubleshooting restarting an engine to running the ditching checklist. Usually the ditching checklist is only about three items. You want to keep everything as familiar as possible to the last 10,000 landings you've done. Except you keep the wheels up! It is very hard to judge the height about the water when landing, so close attention to the altimeter and radar altimeter with a gentle descent rate of about 400 - 600 feet per minute, along with the slowest possible approach speed (If memory serves it is about 140 mph? I've ridden in the cockpit numerous times) would insure maximum probability of keeping the aircraft intact.

So very quick thinking, very deliberate decision making and very skillful piloting!

[Tesha]

16. They apparently discussed trying for Teterboro but decided they couldn't make it.

Teterboro is about 5 miles inland from the Hudson:

http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=Teterboro,+NJ&sll=37.0625,-95.677068&sspn=38.365962,70.224609&ie=UTF8&ll=40.861602,-74.058495&spn=0.143328,0.274315&t=h&z=12&iwloc=addr

It has one longer runway (7000 foot runway 1/19 so not lined up
all that well if you're aborting from LaGuardia) and one shorter
runway ( 6013 foot runway 6/24, so better lined-up but pretty
darned short for a fully-loaded A-320).



http://en.wikipedia.org/wiki/Teterboro_Airport

Tesha

[Hawkowl]

17. Almost impossible

Teterboro looks like it would have been very, very hard without engines. If the pilot miscalculated there would have been a very high number of casualties with the full fuel load and high density residential area.

From the radar track it looks like they took off to the north and to make Teterboro (about 5 miles away from the Hudson) they would have had to have at least about 1800 feet of altitude over the Hudson. I believe they were considerably lower, leaving few options.

These are just a few of the thoughts that fly thru your mind when you are making these snap decisions as a pilot. You actually think about these scenarios before you take off. Although, you usually only discuss losing one engine!

[shireen]

18. thanks for the interesting responses

it makes me appreciate the cockpit crews skill even more. Amazing pilots.

[pokerfan]

19. Requirements?

Usually lack of fuel or an engine problem. :)

Fantastic job by all involved but especially the pilot.

http://news.bbc.co.uk/2/hi/americas/7832642.stm">

http://news.bbc.co.uk/2/hi/americas/7832642.stm">If you could choose a pilot to crash-land your plane, Captain Chesley 'Sully' Sullenberger III would be a good choice.