An unknown number of business jets was expected to be grounded on 1 January, when a US Federal Aviation Administration mandate requiring installation of emergency locator transmitters (ELT) on all turbojets took effect.

Aviation associations failed to secure a last-minute extension to the deadline, which was set almost three years ago, although hundreds of aircraft are still waiting to be equipped.

The National Business Aviation Association, representing Part 91 private operators, and the National Air Transportation Association, representing Part 135 charter operators, tried unsuccessfully to secure a 90-day reprieve, arguing that shortages in the supply of some ELT models were causing installation delays.

The shortages are blamed on equipment manufacturers' inability to meet demand, made worse by the late ordering of ELTs to meet the mandate.

Industry estimates 5-10% of the US business jet fleet could be affected, putting the number of aircraft potentially grounded in the hundreds.

Business jets were previously exempt from the requirement to carry ELTs, but Congress ordered the FAA to remove the exemption after a Bombardier Learjet 35A was found at the bottom of a lake three years after it disappeared on 24 December 1996 on the approach to New Hampshire's Lebanon Municipal Airport.

In April 2000, Congress passed a law requiring the installation of ELTs on all turbojet-powered aircraft by 1 January 2002. The final rule issued by the FAA in December 2000 delayed implementation by two years to give operators more time to equip.

The industry associations say the FAA, in delaying a further reprieve, determined that the firm Congressional mandate for ELT installations could not be extended a second time.

Operators are allowed to install either 121.5MHz or 406MHz ELTs, which activate automatically in a crash, although 121.5MHz devices will be phased out in 2009 in favour of the 406MHz ELTs, which transit at higher power, can be more accurately located by satellites and include a digitally encoded aircraft/owner identification signal that reduces false alarms.

Source: Flight International