Investigators probing a recent crash came upon the aircraft's ELT. Its function switch was in the OFF position. Consequently, after the crash, the ELT exhibited all the volubility of your average Sphinx. "So what?" you say. "ELTs have been doing that since they were invented. What makes this one so different?"
This ELT was equipped with a cockpit control and monitor. With the control, the pilot can reset inadvertent alarms triggered by landings where the down time was confirmed by the local seismograph. The pilot can also trigger the ELT if he or she sees that the flight is about to be rudely interrupted by some wayward mountain.
However, if the ELT is not ARMED, none of the above is possible. The good news is that an ELT with its function switch in the OFF position will not transmit a false alarm. The bad news is that it won't transmit any real ones either.
If your ELT has one of those fancy remote controls and monitors up in the cockpit, you may think that you have all the bases covered. But, unless you have peeked at the ELT itself, hidden back there in the tailcone, you could have a problem.
The remote control and monitor tells you what an ARMED ELT is doing. It won't tell you what an unarmed ELT is doing.
Do you have a real ELT in your aircraft? Or is it one of those Venus de Milo models. You know, unarmed. Why not look and see?
Originally Published: ASL 4/1996
Original Article: Unarmed ELT