What is the power source for an ELT?

The power source for an Emergency Locator Transmitter (ELT) is an internal battery. ELTs are designed to be lightweight, reliable, and able to function independently of other aircraft systems, which is crucial in emergency situations. The internal battery allows the ELT to remain operational even if the aircraft's main power systems fail or are disabled.

Other power sources like solar or wind power are not practical for ELTs, as they cannot guarantee consistent and immediate operation in the varied conditions an aircraft might experience. An external power supply is also not suitable because it could limit the ELT's ability to operate independently when needed. Thus, the internal battery is the optimal choice to ensure that the ELT can automatically activate and transmit distress signals when required, regardless of the aircraft's power status.