What is one of the correct PDI's for the ELT C?

The correct identification for the ELT C (Emergency Locator Transmitter model C) emphasizes the importance of certain pre-deployment indicators (PDIs) to ensure the device is ready for use in an emergency situation. One of the necessary PDIs is that the stop switch should be in place. This indicates that the device is properly activated and prevents it from being accidentally turned off or malfunctioning during critical moments when the ELT is needed for signaling distress.

Ensuring the stop switch is correctly positioned guarantees that the ELT will be operational when it is deployed, thus maximizing the chances of successful location identification in an emergency scenario. This adherence is vital for both safety and regulatory compliance in aviation operations.

The other options reflect various checks that might be relevant in assessing equipment but do not meet the specific requirements or indicators necessary for ensuring the ELT C is fully operational and ready for immediate use. For example, "no stowage required" may refer to different operational protocols, while "the battery needs to be replaced" and "auto mode must be off" do not pertain directly to the PDI checklist for the ELT C.