Landing on water

RE: Landing on water

Actually, that makes sense… the chances of ditching in the sea and being able to evacuate are so minimal, really…

How long were you at Crossair, I used to know one of the guys who did Emergency Instruction, but he was only there about 6 months. Welsh guy. (cue him walking into pub accompanied by regulars bleating…) Anyway, that’s beside the point.

RE: Landing on water

When I worked as cabin Crew for the airline formerly known as Crossair. We were instructed that the lifevest demo only had to be done when taking off or landing at an airport that was surrounded by water.
Also when flying over water for more than 50km.

Jonty

RE: Landing on water

No there aren’t but in reality you are more interested in trying to get an engine restarted.

RE: Landing on water

Most of the people died on board because they inflated there life jackets inside the aircraft and blocked the emergency door’s, that’s what panic does to you!

RE: Landing on water

thankyou wysiwig, interesting!

not many checks are there!!!

lol

coanda

RE: Landing on water

From 757/767 QRH –

Transmit distress signal
Advise crew and passengers

When below 5000′ –
Ground prox gear override (stops the aircraft shouting ‘Too low, gear’ at you!)
Ground prox terrain override (stops it shouting ‘Too low, terrain’)
Air conditioning packs off (stops the aircraft being pressurised any further too allow door opening)
Close outflow valve (this regulates the pressurisation but closing it stops the water getting in)
No Smoking and Seatbelt signs on

On final approach –
Warn the cabin crew and pasengers
Ensure gear is UP
Select flap 30
Hold airspeed at Vref30 until impact and flare to achieve minimum rate of descent at touchdown.

RE: Landing on water

yes, granted, on a calm day I would definitley try to land along the swell, although I suppose it takes a fair bit of wind with an air liner to have much effect……6 of one and half a dozen of the other.

so, what precisley, wysiwig, are the exact ditching order as noted in the FRC’s for the aircraft you fly???

coanda

RE: Landing on water

[updated:LAST EDITED ON 12-07-02 AT 08:50 PM (GMT)]The danger with facing the waves is that clipping the crest of one will cause you to pitch down into the base of the next head on.

RE: Landing on water

thankyou wysiwig for confirming the information written in my previous large post. I did mention that the engines would only hold for a very short while, but their size and the speed of the aircraft would still make a significant decelerative force.

As for aligning for a landing along the troughs of the waves( as you would a plowed field), I would have thought it would have been better to take into consideration the direction and force of the wind(flying along the troughs would put you at maximum crosswind component).

coanda

RE: Landing on water

Thanks you all, this is what I wanted to know 😉

regards,

jw

RE: Landing on water

try again..it’s being an nuisance system today..
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RE: Landing on water

[updated:LAST EDITED ON 12-07-02 AT 10:13 AM (GMT)]and another one…

RE: Landing on water

I know you decided it didn’t count, but strolling through airliners.net I found a pick of the CAL 744 after being removed from the harbour in Hong Kong.
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RE: Landing on water

[updated:LAST EDITED ON 12-07-02 AT 01:31 AM (GMT)]While there would be an initial deceleration from the underslung pods, they wouldn’t remain in place for very long as they are only held on by three ‘fuse’ pins, each about 1/2 inch diameter. These are designed to shear under abnormal loads and (believe it or not) shed the engine. Unfortunately in the case of the El Al 747 at Amsterdam these were in poor condition and caused one engine on one side to separate hitting the one next to it on the way. The QRH (quick reference handbook) for the 757 and 767 contains a checklist named ‘Engine fire, severe damage or separation’ so as you can see inflight separations are taken seriously by Boeing even though they are not common.

Keeping the wings level is a major consideration when ditching as is achieving the lowest possible touchdown speed. As previously mentioned, orientation of the flightpath to the swell is important (less so with bigger aircraft unless the waves are huge).

A year or so back, while doing a 6 monthly sim check I was given a dual engine failure (757-200) climbing out of Tenerife at 18000′ due to volcanic ash ingestion from Mount Teide. When both engines quit you lose all electrics (the APU is not normally left running during flight unless you are doing an autoland or have had certain system failures). There we were at night in a 110 ton glider in total silence staring at black EFIS screens. The engine starters are air driven (off the APU which is not running and needs 1 minute to start up) so the only chance to start the engines is to windmill them requiring at least 300 knots. To achieve 300 knots you will be going down very fast and the QRH states that you need to allow 30 seconds between each movement of the fuel switches. Add to this the fact that the engines you are trying to start are coked up with volcanic ash and we considered ourselves lucky to have got one engine started at 2500′ (we never managed to get the other one going). If both engines had failed to start there would have been bugger all time to contemplate the niceties of the best way to put the thing in the sea so the basic principles I mentioned in the second paragraph would probably be the only ones considered.

Interestingly I spent 3 hours of my life today overflying the Sahara and I have to say I think i’d rather take my chances with a ditching than a crashlanding in the desert.

Hope this helps.

RE: Landing on water

>IS the Ethiopian B767 you are talking about the aircraft
>which was hijacked a few years back?

Video of that crash can be found here;

http://www.cnn.com/WORLD/9611/26/comoros.crash/crash.large.14sec.mov

NOT how one sould land an air liner on water. 🙁

Regards, Glenn.

RE: Landing on water

thanx alot, glad you found it informative…..

coanda

RE: Landing on water

Oh, I wasn’t implying that you plagarised, that was just a comparison used to show the high caliber of quality and information that your post contained. Good work.

GD1

RE: Landing on water

Greekdude, I’m pleased to say that I havent quoted there, but is a simple reasoning of the forces and problems faced by the pilot, and engineer in designing a crashworthy aircraft.

You pay your money……you takes your choice.

coanda

RE: Landing on water

Wow, that’s pretty impressive. Looks like it came straight out of a thesis on water landings, or something.

GD1

RE: Landing on water

Obviously there are some airline employees here, which is good news especially if we have ‘front line’ airliner pilots as it were.

Water Landings:

How do submarines float? they displace less water than is surounding them, unless they want to take on more…..and they sink.

so if you have an airliner which is basically less dense than the water it displaces it will float. You can make rocks float if they have a very low density! however small stone chips work by being lighter(and thus having less force if you like) than the force available to the surface tension of the water.

There are a number of factors that need to be taken into account to achieve successful water landing. I would say the most important factor is having the aircrafts wings level.

You will be aware that if one wing is flying slower than the other, the faster wing will generate more lift, and raise itself, whilst also moving forwards in relation to the centre of gravity, whilst the slower wing will move backwards in relation to the centre of gravity. So if one wing hits the water before the other it is going to retard itself much quicker, and effectively ‘water loop’ generally snapping the wing off a the weakest point.

it is therefore essential that the pilot attempts to hold the wings as level as possible, thus leaving the swell in the lap of the gods to not rise up and grab one wing.

The second most important factor in my mind is the speed at which you enter the water. The faster you go(and the more dense the medium) the greater the deceleration force when you enter a medium denser than the one your currently in, ie water/ground so you can see that speed is proportional to the deceleration force. Which means that the slower you go the lower the deceleration force, there are other factors, but it is well known that if you hit the water from high up it is very easy to break all the bones in your body, whereas if you jump off the side of a pool, the worst you might expect is red ‘belly flop’ marks! lol

A major contributory factor to the survivability of a water landing has to be the location of the engines. Just about all airliner types now have underslung engine pods for one aerodynamic reason or another(the weight of the engines balances the twisting forces encountered by the wings in some cases- a WW2 german finding from the JU287 forward swept aircraft. We can relate a water landing to a vector sum, and hence a solution which sees the engine hitting the water first.

This then provides a turning moment not experienced by the rest of the aircraft. This turning moment 99.99999999999%(!) of the time moves so as to provide a nose down pitching moment( i.e. the water is decelerating the engines only, these are below the CofG and thus, from a side view, nose pointing forward, the turning moment is anti clockwise). So for the short time that the engine mountings(two or three loose bolts in most cases)can hold out against the decelerating forces( again proportional to cross sectional area of the vehicle or engine pod, and density of the medium you are entering, and the speed you are entering that medium)the engines provide a prohibitive turning moment- which is a bit of a bugger really. Ideally for water landings you want the engines above the CofG , on top of the wings, embedded in the wing/fuselage join or around the tail. Again, if an engine seperates the main structure before the other, this can provide a big yawing moment, presenting a larger cross sectional area for the water to act upon, should the fuselage still be still in the air. If an engine digs in, no amount of opposite yaw is going to help you out. Incedentally, this is a reason why you never see water landings with the undercarriage down, apart from the fact that very quickly they will be removed anyway!

So ideally you want to hit the water as slow as you can possibly go, with as high an angle of attack as you can(possibly so that the tail can act as a kind of rudder initially to help out with cancelling turning moments, and decelerating the aircraft slowly, before it begins to fully enter the water. This high AOA will also be productive in that the immediate decelerative forces generated by podded engines is a gradual buildup, instead of a sudden load, structurally this is a good technique to ensure a longer life of any part- shock loading is VERY bad! The wings also need to be level and rock steady, with no flap, with which to enter the water first.

This is of course with the fact the water is a flat calm, and that there is a good headwind, and that some complete and utter bastards havent tried to take over the aircraft.

The chances of a successful water landing in an underslung podded engine aircraft -like the majority of todays fleets-is very very low.

however I know of at least one succesful landing at sea, where the aircraft has in fact been able to float for some time, with some minor injuries only.

This is with regard to a Nimrod R1 which had to make a landing at sea due to a serious failure at low level(it is a well practiced procedure to fly nimrods on one engine for normal patrols at sea.) The aircraft remained structurally complete, and afloat for a number of hours. The crew had ample time to destroy any sensitive equipment and information, before exiting the aircraft.

No doubt the deciding factor in the ability to survive such a landing has to go to the fact that the engines arent underslung. the flat surface is excellent for a short period of planing on the water whilst decelerating slowly.

I have read the RAF inspectorate of flight safety bulletin booklet they published for this accident, I believe it took place in may 95, but I read the publication a few years ago, and this is also where I have seen the only picture of the aircraft, taken from a seaking, as the aircraft floats partially submerged in the ocean.

Looking through the net it appears that the aircraft suffered a massive engine fire on a test flight after a major servicing.

coanda

sorry for the long post!