Emergency Locator Signal Detection and Geolocation Small Satellite Constellation Feasibility Study

Aircraft Emergency Locator Transmitters (ELTs) are vital in helping search and rescue (SAR) teams in locating downed aircraft. Currently there are two types of ELTs available; one transmits at 121.5 MHz and the other at 406 MHz. The transmitters operating at 121.5 MHz have since been abandoned by satellite tracking systems even though these beacons are still available for non-commercial aviation use. Space based receiver decommissioning of 121.5 MHz systems was largely due to an inefficiency of the Very High Frequency (VHF) transmitter beacons; which have a 97% false alarm rate and only provide aircraft location within approximately 20 km of the transmitter. 406 MHz ELTs replaced the old VHF system but many do not broadcast GPS location data. While the Federal Aviation Administration (FAA) mandates all commercial air traffic use the 406 MHz transmitters, many privately owned aircraft still utilize 121.5 MHz and non-GPS 406 MHz ELTs. Small satellites have the capability of providing global coverage for a geolocation SAR constellation due to their low-cost and easily duplicated platform. This study assesses several identifying factors and risks regarding the implementation of such a small satellite SAR system that supports ELTs. Results from this study show that the need for an emergency locator signal detection and geolocation constellation can be seen as a low-cost solution to the current need for a 121.5 MHz and 406 MHz ELT detection system