Hypothetical: Commercial airliner runs out of fuel over the ocean..

Factual Questions
1

So you’re in a commercial airliner flying over the ocean, and suddenly, it comes to everyone’s attention that the plane is running out fuel, with no where to land. So let’s just skip ahead past the panicking, and to the point where you plan on saving your butt. What’s the safest speed an airliner can fly above the ocean, and safely have occupants drop into the water without the plane crashing right away? Can it be done without smacking the water killing yourself? Assuming the plane has already radioed for help with approximate longtitude and latitude so helicoptors and such can rescue the people before they become shark food…

Then there’s the question of, can the pilot make it out safely if the others can? I don’t know how the pilots gonna do it, maybe fly up a little higher, and run outta there and ditch the plane? :eek:

2

Also assuming there’s no time for midair refueling… (ex. Instant massive fuel leak, etc…)

3

The plane will probably break up upon impact with the ocean. Your best chance for survival is if the pilot ditches close to shore. See this CNN story on a bizarre hijacking gone horribly wrong:

http://www.cnn.com/WORLD/9611/24/ethiopia.hijack/

4

Well, after googling on ‘+minimum +flight +speed +747 +mph’ it appears that the minimum flight speed for a 747 is 115 MPH.

I am not positive but would guess that hitting water at 115 MPH isn’t too survivable. I imagine that if you hit the water in a dive positon just right…you’d still die.

Slee

5

Sounds like someone just watched Air Force One, or at least, had it on his mind. What you’re describing is basically the ending of that horrible, horrible movie. :rolleyes:

Google “Gimli glider” for what happens when a 757 runs out of fuel and turns into a glider. The closest thing I can give to a factual answer to any of your questions is the safest speed: somewhere above the stall speed. Without knowing what kind of plane you’re interested in, I can’t give a best glide speed, nor do I know if manufacturers publish airliner stall speeds.

6

Commercial airliners don’t have the capability for in-flight refueling.

I am not a commercial pilot, but part of being checked out to operate any particular airplane is to know the airspeed that will give it the best glide ratio. (i.e. to allow it to cover the greatest distance after an engine failure.) For an airliner at cruising altitude, it could easily glide more than 100 miles. If there’s a runway (or any land) within that distance, the pilot will know about it and head there.

If it is necessary to ditch the plane in the water, I don’t know if the air traffic control system knows the position of ships at sea and can direct a pilot toward a possible rescue vessel.

7

A couple of scenarios I can think of:

  1. If it’s a multi-engine aircraft, then the pilots could use fewer engines in the hope of conserving fuel to get to somewhere less, well, wet for the landing. There’s not many places on commercial flight routes internationally where you are truly in the middle of nowhere. Watching on the international flights that I have been on (with the follow-along in-air maps in the seat back video unit - that is soo cool! :)), I would guess that the planes are never really more than an hour’s flight time from somewhere to land, even if some small fly-speck island. Of course, if this is impossible, due to catastrophic failure (I.E. fuel leak or some such), then that would lead to one of the other scenarios. Also, the glide ratio that Robot Arm talked about, although if it’s a catastrophic failure it would likely be hard to plan ahead for for the best glide path.

  2. Plane crashes into the water, but breaks up and everybody dies. Quite a real possibility, to be honest.

  3. Plane crashes into the water, but stays afloat and everyone gets off, then sinks. Possible, and even something pilots train for in a simulator, but as you pointed out in your OP, probably really difficult. Modern commercial aircraft are designed to support water landings as well as hard landings. I’m not saying they are boats, but they are crash-tested in the design phase to land on large bodies of water. I recall watching flight tests from Boeing when I worked in Seattle (sorry, don’t have the link) where they took a fully-loaded 777 and crash tested it it in a lake. It was impressive, and the plane was mostly intact as well, and floated for an goodly amount of time before sinking. I think most people would have made it out of the aircraft on that one.

You should check out the Gimli Glider, though - cool story and great photos!

  1. Plane crashes into the water but doesn’t sink. Then the people would likely use the plane itself as the mother of all flotation devices and only swim when they had to, and wait for the same scenario as above.

Of course, depending on where the plane went down, the possibility of survivors would change. I rather doubt a plane that crashed north of the Artic Circle would leave many survivors…

Of course this is all just IMO, so any experts out there can feel free to have at me! :slight_smile:

8

Given that the terminal velocity of a falling human is around 120mph, you’d be in the same kind of big trouble as you would be if you were falling into the water from a great height. Sure, you’re coming in at an angle to the surface if you jump from a moving plane, but I think the human body is entirely too squishy for this to be an advantage in the way that it was for Barnes-Wallace’s devices.

9

A commercial airliner that did run out of fuel over the ocean, Air Transat Fl 236:
http://www.airdisaster.com/photos/ts236/photo.shtml

They flew almost 20 minutes without any gas in the predawn hours of August 24th, 2001. Fortunately for them, they found a small island with a runway, and made quite the amazing landing, suffering minor damage (mostly to the landing gear).

10

There is no speed at which you can safely bail out of an airliner and into the water, and no provision for doing this. It would be far safer for the airliner to ditch (i.e. “land” on the water) and for the passengers then to exit promptly, using the energency exit slides as liferafts (for which they are designed).

11

That is the answer I was thinking of. Commercial planes stall speed is still fast enough to make it hurt a lot if you bailed into the water.

However, I am not sure that your forward speed doesn’t help you. It’s all vectors.

You have a ~120mph horizontal speed and a vertical speed depending on your height when you jump. If you jump out ten feet above the water your vertical speed will not be much at all (the speed that will do most of the squishing when you hit). You will skip across the water several times and may survive. Of course, if there are waves and you plough into the side of one it’d be like hitting a brick wall.

My bet is you are better riding the plane all the way in and then exiting afterwards. They do actually float a bit giving people time to get out (unless the plane breaks apart which means all bets are off). They also have life rafts which is better to be in than treading water for who knows how long.

12

One of the problems is that most European and US airliners have a low wing configuration with two or four engine nacelles under the wings. There are a few like the DC-9/MD80 that have all the engines mounted high but for the most part offerings from Boeing and Airbus have this general layout. Jet engines have a lot of drag in the water and are significantly off center. This means that when one hits the water first there is a large lever distance for that extra drag to spin the plan around resulting in a very violent breakup. It’s a different matter when belly landing on hard ground as the drag from the nacelle scraping the pavement isn’t nearly so high as it digging into the water.

A 727 or MD80 might be better suited to ditching at sea but that’s pretty iffy as just touching one wing in the water before the other is enough to spin a plane around.

13

I think you’re less likely to skip over the surface as you are to simply be torn limb from limb, but I concur; your best bet is riding the plane, but you’re probably screwed anyway.

14

Airline pilot here.

At most, you’re about 3 hours from an airport at all times. Usually it’s more like 1-1/2 to 2 hours. However, from the point of fuel exhaustion, your glide time to splashdown is more like 20 minutes.

So it’s critical that fuel leaks (or underfuelling before departure) be detected very early to have a safe outcome. A LOT of attention is paid to this issue throughout every oceanic flight.

The bailout idea is nuts. The lowest & slowest we could safely fly over the ocean surface (with power) is maybe 50 feet and around 140 knots = about 160 mph. Jumping off a 5-story building into a pool would cripple most people. Hitting the water with 150-ish mph of lateral speed as well would make double-sure they’re dead.

If somehow you survived, do you think the airline life jacket you were wearing would still be around you, and do you think it’d still hold air when you pulled the inflate tabs? I’d be amazed if you have any clothes left on at all, much less that floppy, baggy, life vest.

And if folks jumped & somehow miraculously surfaced uninjured with life preserver intact, we’d be leaving a string of individuals floating there hundreds of yards apart. At 1 jumper per second we’d be dropping them at 250’ intervals across the sea. At one per 5 seconds they’d be 1/4 mile apart. The tightest circle we could fly would be maybe 1-1/2 miles in diameter, so even an effort to keep everyone in one group would be a huge area compared to how far folks can swim in the ocean in clothes. 150 feet is farther than most adults can swim under those conditions, even ignoring hypothermia.

The rescue forces would have a very hard time fishing 200-400 individually floating people out of the water and over time the group will disperse. Also, there’d be no way for anyone to get out of the water. Even in the tropics, fatal hypothermia will set in within a few hours; in colder climes, within minutes.

Conversely, a ditching is NOT a guarateed all-hands-die situation.

On a nice sunny day I’d rather land on the Pacific itself than on a Pacific island. Choosing between the North Atlantic and coastal Greenland in February would not be an easy choice, but if the land isn’t farm-field smooth, the water’s the better deal.

Nevertheless, in a ditching in good conditions, most people will be alive and essentially uninjured when the noise stops. The cabin will be essentially intact, seats and belts will hold. The deceleration is well within what your body can stand. The plane will probably break in two someplace, and the unlucky folks right there will be killed, but 5 rows away they’ll be fine.

Then we have a few minutes of float-time to get out the rafts, get people loaded, and we’ve got a whole group to work together & tend the walking wounded. That’s the plan and it works. There hasn’t been a jetliner mid-ocean ditching (yet), but all the pieces have been tested in one mishap or another and all work reasonably well.

We’ll kill 10-20%, injure another 10-20%, but everyone else will survive to fly another day unless we splash down in a raging storm or in Arctic conditions. And even then, it’ll be the post-landing conditions that kill the majority, and that’d be the same or worse risk for any bailouts.

15

FWIW, there actually was a successful commercial jet deep-water ditching, in 1970,in the Caribbean. Fortunately within 30 miles of land bases for rescue missions. 23 fatalities out of 63 aboard, with a major factor apparently being that the pre-ditching prep and evac protocols did not go smoothly and various accidents impeded proper egress (e.g. many people could not don the lifevests properly, one of the rafts got its inflation cartridge triggered before it was out the hatch, etc.)

16

The Comoros Airlines flight mentioned above actually landed while dragging a wing, as can be seen in this video (warning: 1 MB, morbid.) As far as I can tell, it was in fact the left jet engine that caused the final spin and breakup.

17

here

A 50 foot ski jump at 160 mph. is probably too much. Maybe you could it survive stretched out on a surfboard?

18

No problem there cuz he didn’t fall down. If he did it probably wouldn’t have been fun.

19

And IIRC that flight was being flown by hijackers at the time of the ditching.

And to add to what LSL guy said about scattering pasengers all over creation. The original premise is that the airplane is out of fuel. Now, in real life if you figure out that you are going to be forced to ditch, you try to do it BEFORE the fuel is completely exhausted. This gives you much more control of the descent and allows you to take it around if you encounter a wave or something.

That being said, an airplane that is already out of gas and gliding will NOT be able to hang out at 50’ and 140 knots for more than a few seconds. It will be either descending or slowing down. So people either start bailing out at 500 feet, or everyone rushes the exits when you get below 100 feet. Either way, people are dying in large numbers.

And as already pointed out, your chances of survival increase greatly if you stay with the airplane. Liferafts (which have all kinds of goodies: radios, food, water, signal mirrors, fishing kits, etc), the wreckage itself and other people nearby all increase your chances of being found. One lone person, injured from a 50 foot fall and 1/4 mile from anyone else will not last long.

20

Slight hijack - what’s the furthest that a commercial flight can actually be from a suitable airport?