Emergency Locator Transmitter (ELT) Communication

ELT Communication Basics

An Emergency Locator Transmitter (ELT) is designed to send out an automatic distress signal following an accident or forced landing. Modern ELTs transmit simultaneously on 121.5 MHz (VHF) and 406 MHz (UHF), ensuring both local and satellite-based detection. Some military systems also use 243 MHz, while older equipment may operate on 500 kHz.

ELT Activation and Procedures

ELTs are typically activated automatically by impact forces, but can also be switched on manually if needed. Once activated, the ELT broadcasts a continuous distress signal. Pilots should verify ELT activation after an emergency landing and, if possible, position the device for optimal signal transmission. The 406 MHz signal includes digital identification, improving search accuracy.

Distress and Urgency Frequencies

For voice distress (Mayday) or urgency (Pan Pan) calls, use the current working frequency or switch to 121.5 MHz if necessary. 121.5 MHz is monitored internationally and is the primary frequency for distress traffic. In case of communication failure, pilots should also use transponder code 7700 to indicate an emergency.

Actions for Other Stations

When an ELT signal or distress communication is detected, all other stations must maintain radio silence unless they can assist or are directed otherwise by ATC. The controlling ATS unit may instruct others to change frequency or impose silence to ensure clear communication with the aircraft in distress.

Summary Table: Key ELT Frequencies

• 121.5 MHz: Civil emergency (VHF)
• 406 MHz: Satellite detection (UHF)
• 243 MHz: Military emergency (UHF)
• 500 kHz, 2182 kHz: Older/alternative distress (MF)

Understanding these frequencies and correct ELT procedures is crucial for effective emergency response and compliance with international aviation standards.