An Electronic Locator Transmitter (ELT) is a crucial piece of safety equipment installed on aircraft. Its primary function is to aid in the location and rescue of aircraft in the event of an emergency, such as a crash or forced landing. ELTs are designed to transmit distress signals on specific frequencies to alert search and rescue teams about the aircraft's location.
Here is how an ELT typically functions:
Automatic Activation: Many modern ELTs are equipped with sensors that can automatically activate the transmitter upon impact or when subjected to specific forces associated with a crash. This automatic activation ensures that even if the aircraft's occupants are unable to manually trigger the ELT, the distress signal will still be sent out.
Manual Activation: Pilots can also manually activate the ELT if they encounter an emergency situation where assistance is required, such as engine failure or other in-flight emergencies. The ELT is usually equipped with a switch or button for this purpose.
Transmission Frequencies: ELTs transmit distress signals on several frequencies, including the international emergency frequency of 121.5 MHz and 406 MHz. The 406 MHz frequency is particularly important because it is monitored by satellite systems, providing global coverage for distress signal detection.
Locating the Signal: Once the distress signal is transmitted, search and rescue authorities use specialized equipment to triangulate the signal's origin and locate the downed aircraft. This can involve ground-based direction-finding antennas, aircraft equipped with signal detection equipment, or satellite-based systems for 406 MHz signals.
Enhanced Location Accuracy: ELTs equipped with GPS (Global Positioning System) receivers can provide more accurate location information, which helps expedite search and rescue operations. GPS-enabled ELTs transmit not only distress signals but also the aircraft's precise coordinates, further reducing search time and increasing the likelihood of successful rescue.
ELTs are mandatory equipment on most aircraft, especially those operating over remote or oceanic areas where rescue efforts might be more challenging. They play a critical role in aviation safety by ensuring that help can be quickly dispatched in the event of an emergency, potentially saving lives and minimising the impact of accidents.
