The US National Transportation Safety Board is asking the Federal Aviation Administration to work with the US Congress to require that 180,000 or more general aviation aircraft owners equip with more expensive 406MHz emergency locator transmitters (ELTs) rather than the traditional 121.5 MHz units before a satellite network monitoring the signals shuts down in early 2009.
The action came days after, but was not otherwise connected to, the disappearance of famed adventurer and pilot Steve Fossett, who took off in a single-engine Super Decathlon aerobatic aircraft on the morning of 3 September to reportedly scout locations in Nevada for a land-speed record. Fossett's aircraft was most likely equipped with a 121.5 MHz ELT, an analog device which the NTSB says is notorious for generating false alarms. No signals have been picked up from Fossett's ELT from either the COSPAS-SARSAT satellite system that monitors ELT frequencies or by any aircraft participating in the search.
Congress in 2000, as part of the FAA's 2000 reauthorisation bill, changed FAA regulations to allow pilots to equip with either the 121.5MHz or 406MHz ELTs.
The 406MHz alternative, priced at about $1,000 compared with the $200-$500 range for the 121.5 ELT, not including installation, has a lower potential for false alarm due to a stronger signal and digital datastream that provides contact details for the owner. For rescuers, the 406MHz system also provides crash locations accurate to 2-5.5km (1-3nm) compared to 22-28km for the 121.5MHz ELT.
"This smaller search area not only increases the overall likelihood of rescue and the survival of those injured in the crash but also saves the time, money, and resources of emergency responders and mitigates the potential risk to rescuers themselves," says the NTSB.
COSPAS-SARSAT will discontinue its 121.5MHz locator service in February 2009, in large part due to the high false- alarm rate, leading to concerns that GA aircraft equipped with the 121.5MHz ELTs will have fewer chances of being found after an accident. COSPAS-SARSAT will continue to monitor the 406MHz signal.
Source: Flight International
