What function does the Emergency Locator Transmitter (ELT) serve?

The Emergency Locator Transmitter (ELT) is designed to broadcast a distress signal in the event of an aircraft emergency, such as a crash or forced landing. This critical function allows search and rescue teams to quickly locate an aircraft using the signal transmitted on specific emergency frequencies. The ELT's ability to operate automatically upon impact or activate manually by crew members is vital in providing timely assistance and ensuring the safety of any occupants.

In contrast, the other options do not accurately describe the ELT's intended purpose. For instance, detecting altitude changes or measuring cabin pressure are functions typically associated with altimeters and cabin pressure monitoring systems, respectively, rather than the ELT. Similarly, while tracking flight paths can be performed by navigation systems and flight data recorders, that is not within the duties of an ELT. Overall, the primary role of the ELT is to transmit distress signals to facilitate search efforts in emergencies.