Most pilots by now have heard about the plan to end satellite monitoring of emergency locator transmitter (ELT) distress signals broadcast over 121.5- and 243-MHz frequencies after Feb. 1, 2009. But many might not realize there is no specific regulation in the U.S. requiring ELT upgrades to the new 406-MHz standard being adopted in much of the rest of the world.

Part of a transition to ELTs that transmit their distress signals solely on 406 MHz, the change is being driven by Cospas-Sarsat, the international search-and-rescue organization that uses satellite-aided tracking to locate downed aircraft and lost ships. Before the switch, most ICAO member countries are requiring ELT upgrades to meet the new 406-MHz standard. The U.S. and Canada, however, haven’t even issued regulatory proposals for such a change. And that suits many in the aviation industry just fine.

AOPA lobbied against a change to the FARs when the Cospas-Sarsat 406-MHz switchover was announced two years ago, citing the high equipment costs as a main reason why light aircraft should continue to be permitted to fly with old-style 121.5-MHz ELTs. “AOPA recognizes the benefits of the 406-MHz ELT but opposes any attempt to force pilots to upgrade. The unit alone costs about $1,000, with installation adding more to the cost,” the association argued.

NBAA, meanwhile, has recommended that 406-MHz units be purchased for new installations since the equipment has a far better false-positive rate than 121.5-MHz ELTs. The association also points out that as of Jan. 1, 2005, operators must have an automatic ELT that transmits on both 121.5 and 406 MHz when operating on extended flights over water and any designated remote areas to comply with ICAO recommendations. Since then, many ICAO member states have modified their regulations to require installations of 406-MHz ELTs as well. As a result, nearly all business jets that fly outside the U.S. have been upgraded to the 406-MHz standard. The NTSB is urging the FAA to make the equipment mandatory, but so far the agency has made no move to do so.

Until a few years ago, business jets operating in the U.S. weren’t required to carry an ELT at all since the rules applied only to light aircraft. That’s because turbofan airplanes are usually in contact with ATC and, if one crashed, it should be fairly easy to locate, regulators reasoned. Then, on Christmas Eve 1996, a Learjet 35A disappeared while flying the VOR Runway 25 approach to Lebanon Municipal Airport in New Hampshire. It remained missing for more than three years despite the biggest search-and-rescue operation in state history.

The episode led to an ELT mandate in U.S.-registered business jets in March 2004. But what the pilots of Learjet N388LS really needed was a terrain alerting system. Despite the fact that the wind at the airport was reported at five knots, winds at 6,000 were blowing at more than 40 knots. The pilots first tried to fly the ILS approach to Lebanon’s Runway 18 but reported they could not receive the localizer. NTSB investigators determined that the high winds had blown the Learjet more than five miles off course. The crew next attempted to fly the VOR approach, but the pilots started their inbound descent too soon. The airplane hit terrain at 2,300 feet while still more than 12 nm from the VOR.