NavList:

Something to else to consider. Hand held radios for use in airplanes are quite affordable these days. 

http://www.sportys.com/pilotshop/avionics-and-radios/yaesu-fta-550aa-airband-transceiver.html

Since transmission is line of sight, and the antenna on the aiplane is at 35,000 feet, the range is incredable (about 230 NM at 35,000 feet) so it is quite likely that you are within range of an aircraft even though you will not be able to see the plane. The standard emergency and calling frequency for planes is 121.5 mhz which is not covered on a marine band handheld. Airplanes are supposed to monitor this frequency when the radio is not being used for other purposes but I am not sure how many do. It is also common for planes on oceanic flights to monitor 123.45 mhz to chat with other planes to avoid boredom. Here is a link to aviation charts showing the standard routes, click on "world hi." VHF in the range of 118.000 to 136.975 mhz (25 kcs spacing) is used within range of land stations and HF is used offshore. 

http://skyvector.com/

If you are within several hundred miles of these routes you have a good chance of contacting a plane. 

If you are staying within several hundred miles of shore you can find the common VHF frequencies being used on the near shore and monitor them until you hear a plane and some handhelds even have a scanning feature, just start the scanning and then make a call when you hear a plane. Aircraft on oceanic routes also use HF radios so you might also be able to talk to one on your HF. Needless to say, the pilot can relay your mayday to a shore station. 

See;

http://www.hfunderground.com/wiki/MWARA

http://wiki.radioreference.com/index.php/HF_Aeronautical_Communications

http://www.canairradio.com/hf.html

http://www.hamuniverse.com/aerofreq.html

If you think you can't afford a marine handheld, think again. There are very inexpensive ham vhf radios available that can also be programmed to use marine band VHF frequencies. Although the FCC would frown on using one of these ham handhelds on a regualr basis on the marine bnd, the law allows you to use any method to get help in an emergency which includes using a non-approved radio. The Baofeng UV-B5 works fine on the marine band and can be found in the $35 price range. Unfortunately they don't cover the aircraft VHF band. 

https://www.google.com/webhp?sourceid=chrome-instant&rlz=1C1CHNU_enUS596US596&ion=1&espv=2&ie=UTF-8#q=baofeng+radio+ub+b5

gl