UNID possible military traffic
6996 kHz USB 6.996 MHz USB
August 29th, 2017
Heard a partial callsign "xxxx xxxx 40" o or perhaps ending in 040 calling another station on 6996 kHz USB. I think the second part of the callsign was "flight" but I'm not 100% sure on that. At 1403 UTC, heard "nothing heard, out". Sounded very much like an aircraft calling a ground station or maybe another aircraft, reminded me of USAF communications heard on 6739 USB, 11175 USB, etc. Very professional radio operating procedures...unfortunately I missed most of the callsign.