Originally Posted by SNA1K
The two ports on UA are for their special noise cancelling headphones..just plug your single 3.5mm plug into the smaller of the two plugs and it will work fine..no adapter required.
Last time I flew in C, the 3.5mm (1/8") jack was the larger one. I don't routinely travel with a tiny ruler, but I think the small plug is a 2.5mm (3/32") jack, which is what's on your cell phone headsets.