After former US Army helicopter pilot Dr. Mark Garrison published his book GUTS ‘N GUNSHIPS: What it was Really Like to Fly Combat Helicopters in Vietnam, he came across remarkable audio from a 1969 mission in Vietnam. In the clip he posted, Garrison and two other pilots are heard calmly coordinating a troop extraction. The full conversation is available on SoundCloud
I discovered, through a perfect storm of events, an audio recording of my involvement in the extraction of American forces that were about to be overrun by thousands of enemy troops. This mission is described in the book. The following is a small excerpt of the actual radio transmissions.
Years later, Garrison spoke about the mission in greater detail.