One, Both, or None?

I received the typical late-night call.   "We've got SARSAT hits near your location," the IC said.   Living near an Air Force Base, I knew where the offending signal likely was.   I was right, but only by half.

The signal was a dual-freqency on 121.5 MHz and 243.0 MHz.   All of the hits were pretty close together, but were several miles south of the base.   In hindsight, they were all well within the advertised tolerances.   We activated the squadron's ground teams and prepared for a late evening.

When I was talking to the Air Force Base's Command Post, they relayed to me, "they found it, they found it!"   I foolishly believed that this was true and phoned my MC.   Just for giggles, though, I went outside and took a DF reading from my driveway.   I received a 121.5 MHz ELT signal as clear as day--from my DRIVEWAY!   The Life Support personnel on base had located a 243-only URT-33/C beacon that had been inadvertantly activated and shut it down.   There had to be a second signal.   Oddly enough, I couldn't receive a signal on 243.0.  

So we tracked the 121.5 signal to an Air Force T-1 Jayhawk trainer jet.   The aircraft is essentially a (Beechcraft 400) civilian business-type jet bought off-the-shelf.   As such, it has a civilian-type ELT in it.   The aircraft had a malfunctioning ELT--obviously.   The beacon would only transmit on 121.5 MHz.   Another beacon on 243.0 supplied what we believed to be a dual-frequency ELT.   A sort of two-for-one deal.

The moral of the story is VERIFY that your signals, plural, have been shut down when you locate the target.   Malfunctioning beacons can choose to transmit on both 121.5 or 243.0, or sometimes just one of them.

Of important note is that one should always ask the question, "is there a signal on 121.5, 243.0, or both?"  However, don't trust the answer.  The answer given is, more often than not, incorrect as it is filtered through many people.