When are non-rechargeable ELT batteries required to be replaced?

The requirement for replacing non-rechargeable ELT (Emergency Locator Transmitter) batteries is based on the principle of ensuring reliability during emergencies. Non-rechargeable ELT batteries are mandated to be replaced after 50% of their useful life has expired. This approach ensures that there is sufficient power available for the transmitter to function effectively when needed.

It is essential for pilots and aircraft operators to monitor the battery life closely and adhere to this guideline. Non-rechargeable batteries can degrade over time, and the lifespan can vary based on the type of battery. By replacing them after 50% of their useful life, the likelihood of a malfunctioning ELT in an emergency situation is significantly reduced, enhancing overall safety.

Other options, such as requiring replacement every year or every six months, do not specifically align with the useful life percentage and may result in unnecessary replacements or, conversely, inadequate battery life at critical moments. Similarly, the notion of replacing them after only the first hour of use does not reflect the operational reliability needed for such crucial safety equipment, which is designed to last throughout its operational life until the 50% threshold is reached.