Shutter wrote:
"The signal tone was coming from Evergreen field north of Government island miles away from Tbar. it was on frequency 243.0 which is a emergency broadcast freq. it moved to Reynolds Aluminum plant west of Vancouver before fading out. this was on 12/26/71 at 3:30
...tracking device in the chutes go off when deployed. I don't think they start until deployed."243.0 MHz is the military aviation emergency frequency. The civilian equivalent is 121.5 MHz.
Civil 121.5 beacons have a harmonic that can be heard on 243.0. The converse is not true. Military rescue aircraft that hear a 243.0 signal briefly switch to 121.5 to see if they are hearing a harmonic of a civilian beacon. MANY civil emergency beacons are accidentally triggered. 8786 false alerts in 2018. You are not allowed to view links.
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Login Very few military ones are accidentally triggered.
The typical 243.0 "pinger" beacons were rigged to turn on either upon ejection or canopy deployment depending on the type of aircraft and equipment. Some B 52 aircrew over Vietnam disabled the auto-activation feature because the enemy had gear that could hear signals on 243.0 and used it to capture airmen.
My opinion is that the beacons put in McCoy's rigs were turned on when installed. It would have been too difficult (and also visually obvious externally) to rig them for automatic turn on. Battery life is typically 20 hours or more continuously transmitting.
Modern civil emergency beacons send a coded signal on 406.0 MHz identifying the beacon and sending GPS position. These modern 406 beacons also have a low power transmitter on 121.5 which allows ADFs to point towards the transmitter. The 121.5 harmonic can also be heard on 243.0.
Only military aircraft have ADFs that can receive and DF on 243.0. Civil aircraft VERY rarely have VHF ADFs that can receive and DF on 121.5. typical coverage for civil aircraft ADFs tops out at 1750 KHz, miles below the VHF freq of 121.5 MHz.
Happy to answer chute and beacon Qs.
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