How can a pilot verify that an aircraft's ELT is not transmitting?

Listening on 121.5 MHz for a signal is a practical method for a pilot to verify that an aircraft's Emergency Locator Transmitter (ELT) is not transmitting. The 121.5 MHz frequency is designated for emergency signals, and an operational ELT will broadcast a distress signal on this frequency. By listening for a continuous signal on this frequency, a pilot can determine if the ELT is functioning properly. If there is no signal detected, it suggests that the ELT may not be transmitting as intended.

This method is straightforward and often part of pre-flight checks to ensure safety equipment is working correctly before embarking on a flight. It allows for immediate verification rather than relying on external indicators or systems that may not provide real-time information.