ELT

ELT (Emergency Locator Transmitter) is a distress beacon designed to transmit a signal after an aircraft crash, enabling search and rescue (SAR) teams to locate the wreckage. ELTs are mandatory equipment on most aircraft worldwide.

Types of ELT:

• Fixed (AF): Permanently installed, automatically activated by impact (G-force sensor)
• Portable (AP): Can be removed and manually activated by survivors
• Automatic Deployable (AD): Automatically ejected and activated upon impact or immersion

Modern ELTs transmit on 406 MHz, which is monitored by the Cospas-Sarsat satellite system. The 406 MHz signal includes a unique identification code registered to the specific aircraft, enabling rapid identification and reducing false alerts. Many ELTs also transmit a homing signal on 121.5 MHz for close-range direction finding.

ELTs equipped with GPS provide position accuracy within 100 meters, compared to several kilometers without GPS. Regular testing and battery replacement (every 5–6 years) are required maintenance items.