Aircraft Operating An ELT On 121.5 MHz Will Soon Be Prohibited


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Aircraft Operating An ELT On 121.5 MHz Will Soon Be Prohibited

Shane Nolan

June 24, 2010 - Distress radio beacons, also known as emergency beacons, ELT or EPIRB, are tracking transmitters which aid in the detection and location of boats, aircraft, and people in distress.  

Most aircraft today are equipped with an ELT operating on a frequency of 406.0-406.1 MHz that interface with Cospas-Sarsat, the international satellite system for search and rescue (SAR). When activated, such beacons send out a distress signal that, when detected by non-geostationary satellites (A non-geostationary satellite is one where its position relative to the Earth is not fixed), can be located by trilateration.  

There are still a number of aircraft mostly older aircraft that have onboard their aircraft ELT?s that operate on a frequency of 121.5 MHz. Up until October 2000 Cospas-Sarsat had been monitoring this signal but because of accuracy and false alerts the signal was dropped. At present aircraft operating on 121.5 MHz are still being monitored by air traffic control and pilots. 

ELT On 121.5 MHz  


The Federal Communications Commission (FCC) which licenses this frequency has concluded that ?there is no dispute that 406.0-406.1 MHz ELTs are more accurate and reliable than 121.5 MHz ELTs, and minimize false alerts.? 

The 406 MHz ELT transmit a digital signals, the ELT can be uniquely identified almost instantly (via GEOSAR), and furthermore, a GPS or GLONASS position can be encoded into the signal, which provides instantaneous identification of the registered user and its location. Frequently, by using the initial position provided via the satellite system, SAR aircraft and ground search parties can home in on the distress signals from the ELT and come to the aid of the aircraft. 

?We believe that if 121.5 MHz ELTs are no longer available, aircraft owners and operators will migrate to 406.0-406.1 MHz ELTs, and the advantages of 406.0-406.1 MHz ELTs will provide safety benefits for search and rescue teams as well as aircraft pilots, crew and passengers, while also preserving search and rescue resources for real emergencies. Were we to permit continued marketing and use of 121.5 MHz ELTS, on the other hand, it would engender the risk that aircraft owners and operators would mistakenly rely on those ELTs for the relay of distress alerts?. 


The FCC, after it had requested input from the general public, end-users, manufacturers, etc. a proposed rule (the rule has not become law as of yet) that states in essence that the use, certification, manufacture, importation, sale or continued use of 121.5 MHz ELTs will be prohibited.  

This rule will go into affect 60 days after the proposed rule is submitted to the Office of the Federal Register at which time it will be placed in the Federal Register (since March 14, 1936), is the official journal of the Federal Government of the United States that contains most routine publications and public notices.


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