Definition
Internationally designated radio frequencies reserved for emergency communication by aircraft and vessels in distress. The two primary aviation distress frequencies are 121.5 MHz (VHF, civilian) and 243.0 MHz (UHF, military), monitored by air traffic control facilities, search and rescue services, and many aircraft in flight. These frequencies are also used by emergency locator transmitters (ELTs) to broadcast a signal when an aircraft has crashed or made a forced landing.
Plain English
Special radio channels set aside for pilots and crews to call for help in an emergency. Anyone hearing a call on these frequencies treats it as urgent.
Context Anchor
Pilots encounter distress frequencies in radio procedures, emergency training, flight planning, and aircraft radio or emergency equipment discussions.
Derivation
Distress comes from the Latin districtus, meaning 'drawn apart' or 'in difficulty.' Frequency refers to the radio channel itself. Together: the channels reserved for those in serious trouble.
Why Pilots Care
These frequencies ensure emergency calls reach air traffic control, other aircraft, and rescue services without interference from routine traffic.
Intuition Check
Do not think of distress frequencies as normal chat or practice channels. They are emergency channels for urgent help or locating an aircraft in danger.
Example Sentence 1
After losing communication with the tower, the pilot tuned to 121.5 MHz, one of the distress frequencies, to make contact with any nearby station.
Example Sentence 2
Search and rescue teams continuously monitor the distress frequencies for any calls from aircraft in trouble.