Final answer:
The ELT must have a battery capable of providing at least 48 hours of activity post-activation, and it is essential to test it outside with a clear view of GPS satellites for location accuracy.
Step-by-step explanation:
The Emergency Locator Transmitter (ELT) is an independent system integrated into aircraft for use in emergency situations. In accordance with international regulations, the battery pack that is a part of the beacon must provide at least 48 hours of beacon activity after it has been activated due to an incident. For accurate operational testing of the 406 MHz ELT, it is essential to position the aircraft outside to ensure an unobstructed line of sight to the GPS satellites. This is crucial because the ELT relies on signals from these satellites to determine the location of the aircraft with the help of their onboard atomic clocks which need to be precisely synchronized to factor in relativistic effects for accurate location determination.