FAA Ground School Practice Test

When must batteries in an emergency locator transmitter (ELT) be replaced or recharged if rechargeable?

1. When the ELT has been used for more than one cumulative hour

2. After two years of use

3. Every six months

4. When the battery indicator shows red

The correct answer is: When the ELT has been used for more than one cumulative hour

The correct answer is that batteries in an emergency locator transmitter (ELT) must be replaced or recharged, if rechargeable, when the ELT has been used for more than one cumulative hour. This guideline is put in place to ensure that the ELT remains operational and ready for use in emergency situations. The one-hour cumulative use is critical because it is the duration after which the performance and reliability of the ELT's battery may no longer be guaranteed. If the ELT has been activated and used for this significant amount of time, it is essential to assess the battery's condition to ensure that it can function effectively when needed. In contrast, the timeframe associated with options involving two years of use, every six months, or a battery indicator showing red could lead to misunderstandings about battery maintenance. These other options do not address the immediate functionality and reliability of the ELT based on actual use, which is why the one-hour cumulative usage guideline is the correct criterion for battery maintenance.