Question number one, the one I had in my mind primarily upon writing this OP, is whether airliners over the pacific or atlantic that are in serious peril have decent methods of both communicating with and finding surface vessels, especially large passenger liners like the QM2, such that they can ditch in an appropriate place and offload everyone. And if so, what are these methods?
But of course I have a somewhat more complex question than that and the complexity comes from expanding the scope. The expansions are pretty much obvious.
How does someone ditch a balloon by a ship, hundreds of miles from anywhere, for example?
Will your average aircraft that suddenly finds itself out of fuel over the ocean find an ocean going craft to land beside? And to what extent will that be luck?
There are many more questions I could ask about this theme. Please use your imagination to answer them!
Big ocean little ship. Hard to come down next to. And a plane going downdoes not have much time to locate where ship is and fly to the location.
If the pilot got on the emergency freq. they should be able to talk to any ship within 500 miles.
I don’t know that ships have the ability to monitor the aviation emergency frequencies. The marine emergency channel is different.
Airliners are pretty decent gliders. From cruising altitude I think you can get 100 miles in any direction, assuming that whatever knocked out the engines didn’t take something else important, too.
But a 100 mile radius in the middle of the ocean still ain’t much.
You are right the pilot would have to swwitch over to the marine emergency channel.
The pilot doesn’t have marine channels.
While there aren’t many cruise ships on the open ocean, there are LOTS of tankers and container ships busy keeping the global economy chugging along. These ships aren’t just randomly distributed across the ocean, but are concentrated in shipping lanes that generally follow great circle routes between major ports and strategic passages, like straits or canals. Within shipping lanes the distances between ships may not be that large compared to the vastness of the ocean, on the order of a few miles or less for very busy shipping lanes near port to a few tens of miles for less crowded ones. Since most transoceanic flights also roughly follow great circle routes between major port cities, air routes and shipping routes significantly overlap. Compare this map of global shipping routes with this map of Delta Airlines international flight routes.
So at any given moment odds are decent that your hypothetical airliner will be within the vicinity of a large transport ship. With a glide ratio just over 15:1, a 747 flying at 35,000 feet will be able to remain airborne for about 100 miles, which should give them enough time to spot a surface ship. Communicating with the surface ship would probably be an issue, but I imagine when the captain of a container ship sees an airliner belly in for a water landing a few miles off his bow, he’s not going to ignore it and will probably get the message: “Gee, it looks like those people might need help!”
Obviously a container ship isn’t going to have accommodations for 400 people, but they should have space and provisions to provide temporary safety for the rescuees. If nothing else there’s plenty of deck space. Lifeboats could be used to ferry survivors to the ship, and all large vessels would have a ladder or gangplank normally used to allow pilots to board the ship.