Date Approved


Embargo Period


Document Type


Degree Name

M.S. in Engineering


Mechanical Engineering


Henry M. Rowan College of Engineering


Gabler, Hampton C.


Aeronautics--Safety measures; Survival and emergency equipment--Testing


Mechanical Engineering


Emergency locator transmitters are radio beacons that help locate aircraft in distress and are required on many aircraft, primarily general aviation aircraft. The purpose of an emergency locator transmitter is to assist SAR teams in rapidly locating downed aircraft so aid can be provided to the pilot and passengers. The first emergency locator transmitters, still in use today, were found to have crash activation rates of only twenty-five percent (25%). This means that three out of every four crashes are not detected by these devices. Newer emergency locator transmitters were found to have crash activation rates of seventy-three percent (73%) to eighty-two percent (82%), leaving room for improvement.

In addition to emergency locator transmitter having a marginal crash detection rate, emergency locator transmitters were found to have an appalling and inexcusable false alarm rate. The false alarm rate of all emergency locator transmitters is greater than ninety-four percent (94%). Many explanations have been suggested for this high false alarm rate including hard landings and inadvertently activating the emergency locator transmitter during maintenance. This research project investigated the sensitivity of emergency locator transmitters to these non-distress impact events.

This research project consisted of two (2) main tasks: creation of a database of non-distress deceleration pulses and investigation of what types of non-distress events cause activation. In creating a database of non-distress event data, a portable data acquisition system was developed. There were also two (2) supplemental objectives: impact testing of the enhanced emergency locator transmitter and reverse engineering of a 406-Megahertz emergency locator transmitter.

The database of non-distress impact events included landing pulses from a Cessna 152, normal operation vibrations from a Cessna 152, and impact pulses from an ELT being dropped onto a hardened surface. Landing data and normal operation data were not found to cause false alarms, while mishandling an ELT was found to be a cause of false alarms.