<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by trust77:
On their 767-400, my sony head set works well in coach. In BusinessFirst however, sound comes only comes out of my left head set.</font>
I haven't noticed the patteren yet, but on newer aircraft, it does appear that at least one of the sockets for the two-prong airline headset plug is also rigged for stereo if a regular headset plug is inserted. It may be only on one of the plugs, so if you plug in a regular headset and get sound out of only one side, try the other plug.
Of course, to be sure that you'll have sound in both ears, go to Radio Shack and get an adaptor. It will probably cost more than the $5 headset fee, though.