Which type of ELT is considered automatic fixed?

An automatic fixed emergency locator transmitter (ELT) is designed to activate automatically upon impact or when it is submerged in water, transmitting distress signals to assist search and rescue operations. The correct answer identifies a specific type of ELT that is permanently mounted in an aircraft, allowing for immediate signal broadcast in case of an emergency without requiring pilot intervention.

In contrast, other options represent different types of locator devices. An EPIRB (Emergency Position Indicating Radio Beacon) is typically a portable device used at sea, a PLB (Personal Locator Beacon) is also portable and is used by individuals for personal emergencies, and the choice labeled as 'S' does not directly correlate to a recognized type of automatic fixed ELT. This distinction is important as each device has its specific application and operational context.