What are the primary frequencies on which most ELT beacons transmit?

What are the primary frequencies on which most ELT beacons transmit?

• A. 121.5 mHz and 400 mHz
• B. 117.5 mHz and 430 mHz
• C. 118.5 mHz and 406 mHz
• D. 121.5 mHz and 406 mHz

Answer: (D)

Emergency Locator Transmitters (ELTs) are crucial safety devices used in aviation to aid in locating downed aircraft. The primary frequencies on which most ELTs transmit are, in fact, 121.5 MHz and 406 MHz. The 121.5 MHz frequency is an older emergency frequency that is monitored worldwide. Although its use has diminished with advances in technology, it remains a secondary frequency for many ELTs. The 406 MHz frequency is more modern and offers several advantages, including improved signal strength, faster detection by search and rescue operations, and the capability to send digital distress signals that include valuable information such as the aircraft's identification and GPS coordinates. The pairing of these two frequencies allows for both legacy and more advanced systems to coexist, ensuring broader safety measures are in place for locating downed aircraft. The other frequency combinations listed in the other options, such as 117.5 MHz, 430 MHz, and 118.5 MHz, do not align with standard ELT frequencies and do not serve the emergency functions that 121.5 MHz and 406 MHz provide.

Emergency Locator Transmitters (ELTs) are crucial safety devices used in aviation to aid in locating downed aircraft. The primary frequencies on which most ELTs transmit are, in fact, 121.5 MHz and 406 MHz.

The 121.5 MHz frequency is an older emergency frequency that is monitored worldwide. Although its use has diminished with advances in technology, it remains a secondary frequency for many ELTs. The 406 MHz frequency is more modern and offers several advantages, including improved signal strength, faster detection by search and rescue operations, and the capability to send digital distress signals that include valuable information such as the aircraft's identification and GPS coordinates.

The pairing of these two frequencies allows for both legacy and more advanced systems to coexist, ensuring broader safety measures are in place for locating downed aircraft. The other frequency combinations listed in the other options, such as 117.5 MHz, 430 MHz, and 118.5 MHz, do not align with standard ELT frequencies and do not serve the emergency functions that 121.5 MHz and 406 MHz provide.