At the request of the FAA, the Federal Communications Commission (FCC) last week stayed a proposal that would have prohibited the 'certification, manufacture, importation, sale or use' of emergency locator transmitters (ELTs) that transmit distress alerts on 121.5 MHz. FAA regulations require U.S.-registered aircraft to carry fixed emergency locator transmitters, but the rule doesn't specify whether they should operate on 121.5 or 406 MHz. Although satellites have not listened for 121.5-MHz signals since Feb. 1, 2009, the frequency is still monitored by ATC, the military and other pilots. Aviation groups, including NBAA and AOPA, and the FAA protested the FCC proposal when it was floated in June last year. Though NBAA opposed the mandatory prohibition of 121.5-MHz ELTs, the association is also recommending that operators phase out 121.5-MHz ELTs gradually in favor of 406-MHz ELTs, in conjunction with any new equipment, aircraft and avionics upgrades. Since July 2008, general aviation aircraft that fly internationally have needed ELTs that can transmit on both 406 and 121.5 MHz.