From: Jim Friedman NBC 10, Philadelphia, Pa
When you need that audio of cockpit chit-chat and you can’t plug in to their system, try this. Take the passenger headset and remove the earmuff pad from one side of the headset. Place your lav mic head between the foam and the speaker. Tape the lav head to the speaker. Put the padded ring back on to the headset. Press both earmuffs together and wrap gaff tape around the headset to squeeze it together. I never had a problem with this method plus the pilot will be glad when you don’t have to “tamper” with his comm system.
I’ve used a similar method to interview pilots in-flight. Everyone in the aircraft (me, pilot and reporter) were wearing headsets so we could communicate during the flight. I stuck the lav in the headset I was wearing and recorded the reporter/pilot interview that way as they talked to each other over the comm system. The space inside the earmuff was large enough for me to do this comfortably and get pretty decent audio. It still sounded like an airplane comm system but it definitely made the interview much more interesting than interviewing the pilot on the runway.