"In the event of an emergency, your seat cushion may be used as a
flotation device."

My question is, has anyone ever actually ever survived a large plane
crash into a large body of water?

To be a bit more specific, one is led to believe that if there is a
problem on a large airplane (727, 747, Airbus 300, etc) while
travelling over an ocean the pilot might try to make a water landing.
In such a case, we are supposed to do things like use our seat cushion
as a flotation device, put on our life vests and break out the
inflatible boat near the exit row. Have these saftey measures ever
saved anyone? If so, please point me to info about it.

I've done a bit of looking at the http://www.ntsb.gov database but found no large
airplane water landings with any survivors.

Hi! Thanks for the question.

Here are articles providing reports of survivors of different large
airplane crashes in large bodies of water.


?The ditching site was confirmed on radar with the assistance of a
PanAm flight that diverted for that purpose. Other fixed-wing aircraft
orbited the area until the US Coast Guard, Navy, and Marine Corps
helicopters began picking up survivors.?

?McDonnell Douglas DC-9-33CF?
http://aviation-safety.net/database/record.php?id=19700502-0 


-----------------
?On May 8, 1978 at about 9:20 p.m., a National Airlines 727 with 52
passengers and 6 crew crashed into Escambia Bay on approach to the
Pensacola Airport. Three of the passengers drowned while awaiting
rescue.?

?National Airlines 727 Crashes Into Atlantic?
http://www.super70s.com/Super70s/Tech/Aviation/Disasters/78-05-08(National).asp 

National Airlines: Boeing 727-235
http://aviation-safety.net/database/record.php?id=19780508-1 


--------------------------
?While attempting a landing near Moroni in the Comoros Islands the
aircraft ran out of fuel and ditched near a beach. Ten of the 12 crew
members and 117 of the 160 passengers were killed.?

?The aircraft initially dragged the left wing tip in the water,
followed by the left engine.?

?Ethiopian 767 in the Comoros Islands?
http://www.airsafe.com/journal/issue6.htm#comoros 


-----------------------
?But one airliner you rarely hear about today is the Boeing
Stratocruiser. The Stratocruiser was a double deck airliner built by
Boeing that used the same wing and tail design as the late model
B-29s/B-50s.?

?When the crew couldn?t get the prop to ?feather? and their efforts to
stop the engine also failed, the captain alerted the 24 passengers
they might have to ditch the plane. Everyone was calm and the
stewardesses efficiently prepared the passengers for ditching.?

Note: All Crew and Passengers Survived

?ART REPORT: Memories triggered by art provide an added dimension to the work?
http://www.generalaviationnews.com/editorial/articledetail.lasso?-token.key=7299&-token.src=column&-nothing

?Boeing 377 Stratocruiser 10-29?
http://www.aviation-safety.net/database/record.php?id=19561016-0 


Search terms used:  
water landing survivors

I hope these links would help you in your research. Before rating this
answer, please ask for a clarification if you have a question or if
you would need further information.
                             
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Easterangel-ga

Exactly what I was looking for. Thanks!