Under what condition must the emergency locator transmitter (ELT) battery be replaced?

The requirement to replace the emergency locator transmitter (ELT) battery comes into play after the transmitter has been in use for more than one cumulative hour. This guideline ensures that the ELT remains effective and ready for use in case of an emergency.

After activating an ELT, continuous use for an extended period could lead to battery depletion, potentially jeopardizing its reliability when it's most needed in an emergency situation. By having a strict limit of one cumulative hour for the battery's use before replacement, it minimizes the risks associated with unexpected battery failure during critical times.

While other conditions may indicate maintenance or check-ups, only the cumulative hour of use specifically mandates a replacement to maintain operational safety and effectiveness.