C-91a ELT (121.5/243.0 MHz)

An Emergency Locator Transmitter (ELT) is a device that can be manually or automatically activated to transmit a distress signal to a satellite. ELTs that activate automatically use a “G-Switch” (gravity switch) that triggers the ELT when it senses that a crash has occurred. With ELTs, Search and Rescue teams may more easily pin-point the exact location of a downed aircraft. Subpart 0 of Part 21 of the Federal Aviation Regulations states that no person may operate a U.S. registered civil aircraft unless an approved automatic type emergency locator transmitter is attached to the aircraft.

TSO C-91a prescribes the minimum performance standard that an ELT operating on 121.5 and 243 Megahertz must meet.

The Artex ELT 110-4, ELT 200, ELT 100 HM and ELT 200 HM are TSO C91a and Cospas/Sarsat approved and must meet standards set forth as per RTCA/DO-183.

Due to the limitations of the 121.5 MHz technology, Cospas/Sarsat will terminate satellite monitoring of 121.5 MHz on February 1, 2009. The only emergency frequency monitored through the Cospas/Sarsat satellite system will be 406 MHz. Artex no longer manufactures or repairs C91a ELTs.  Battery Packs for certain models are still availalbe.  Please see Discontinuation Letters in the Download section of this page.