Effect of 406 MHz ELTs and COSPAS-SARSAT Cessation of 121.5 MHz ELT Monitoring on Search and Rescue Duration for General Aviation Aircraft Accidents in the Contiguous United States

Emergency Locator Transmitters (ELTs) are credited with saving hundreds of lives every year in the United States. Following an aircraft accident, these devices transmit an emergency beacon signal to the COSPAS-SARSAT satellite network, directing search and rescue forces to the crash site. In recent years, this constellation has been plagued by ELT false alarms, propagating a technology transition to new 406 MHz ELT systems. In 2009, the group ceased monitoring of 121.5 MHz ELTs, degrading search and rescue capability for legacy ELTs. The Federal Communications Commission twice attempted to enact regulations to mandate industry-wide transition to 406 MHz ELTs, however, their efforts have met strong resistance by pilot advocacy groups. The purpose of this study was to determine if 406 MHz ELTs resulted in lower search and rescue durations than 121.5 MHz systems. Furthermore, the study sought to discover if the cessation of 121.5 MHz ELT monitoring in 2009 resulted in a change in search and rescue mission duration for legacy ELTs. The study collected data from an Air Force Rescue Coordination Center search and rescue database for search missions occurring between 2006-2011. To compare search durations of 406 MHz and 121.5 MHz ELTs, data was assessed using orthogonal contrast testing between historical mission durations. The same contrast technique was applied to 121.5 MHz ELT missions conducted from 2006-2008, which used the COSPAS-SARSAT network, and missions conducted from 2009-2011, in which 121.5 MHz satellite detection was deactivated. The study revealed 406 MHz ELTs offer a statistically significant advantage in search duration over 121.5 MHz ELT models. Additionally, the study determined there was no significant difference in mission durations for 121.5 MHz ELTs monitored by the COSPAS-SARSAT network and those missions which did not receive satellite coverage. This research will likely aid both regulators and advocacy groups in shaping future policy decisions for mandatory 406 MHz ELT implementation