Who uses ELTs?

Question

Do all commercial and private aircraft in the US have to have ELTs on board? Analogue or digital?

Answer 1

No. Most general aviation aircraft have ELTs on board, but most airliners do not. The reason airliners are exempt is that they're constantly under the watchful eye of air traffic controllers, so their position is always known.

The US is in the process of converting to a new type of ELTs. The old versions broadcast a simple swept tone signal on 121.5 MHz (VHF) and 243.0 MHz (UHF). The new ELTs broadcast this swept tone on 121.5 MHz and both coded GPS position information and a unique serial number on 406 MHz. Both types are sensed by a constellation of search and rescue satellites, but the old type will not be sensed after 2009.

For complete info, see: http://en.wikipedia.org/wiki/Emergency_locator_transmitter