Where must the Emergency Locator Transmitter (ELT) be installed in an aircraft?

The Emergency Locator Transmitter (ELT) must be installed as far aft as possible but still in front of the tail surfaces to ensure optimal functionality during an emergency. The placement of the ELT in the aft section of the aircraft, yet forward of the tail surfaces, allows it to maximize its exposure during an accident, ensuring better chances of signal transmission and retrieval. This location reduces the chances of the ELT being damaged during a crash and takes advantage of the aerodynamics of the aircraft, enabling the device to function effectively in the harsh conditions that may follow an emergency landing.

For instance, positioning it too close to the cockpit or in areas like under the passenger seats could expose the ELT to greater risk of damage or interference during a crash. Additionally, positioning the ELT in the engine compartment would not be practical as this area could be subject to extreme heat or damage, further reducing the reliability of the signal sent to rescuers. Thus, the best practice is to choose a location that balances safety and operational functionality, which is why the correct answer emphasizes an aft location, maintaining an optimal distance from destructive zones in an aircraft accident scenario.