Distress and emergency frequencies
Three frequencies, not interchangeable:
| Frequency | Role | Cite |
|---|---|---|
121.5 MHz |
International VHF aeronautical emergency. Any aircraft required to carry two-way VHF radio must be able to communicate on it | CAR 602.143; TC AIM SAR 4.5 |
243.0 MHz |
International emergency for UHF-equipped (military) stations, paired with 121.5 MHz | TC AIM SAR 4.2 Note 3; TC AIM RAC 1.5.7; flight-plan UHF indicator "U"; DND per AC 100-001 glossary |
126.7 MHz |
Canada-specific. Monitoring rules: see vhf-frequency-position-report-procedures |
TC AIM SAR 4.2 Note 3 |
Continuously monitor 121.5 MHz (TC AIM SAR 4.5):
- Who: pilot in sparsely settled area, or Canadian aircraft over water more than
50 NMfrom nearest shoreline. - Unless: already on another VHF aeronautical frequency, or equipment limits or essential cockpit duties prevent monitoring both.
- Dual VHF: strongly recommended to monitor
121.5 MHzat all times (TC AIM SAR 4.2 Note 3).
121.5 MHz as fallback:
- Establish contact when aircraft lacks the published frequency, or equipment failure rules out the normal channel (TC AIM SAR 4.2 Note 4).
- Distress call unanswered on working frequency: repeat on
121.5 MHz, or any other frequency available (RIC-21 6.3).
No frequency is mandatory in a genuine emergency (TC AIM SAR 4.2 Note 1):
- Pilot may use any available frequency or any means to attract attention and get assistance.
- Any other person may use any means available to assist the emergency aircraft.
Trap: 121.5 MHz: "at all times" recommendation for dual-VHF aircraft, plus monitoring near water or over sparsely settled areas. 243.0 MHz is the UHF/military counterpart, not a Canadian civil rule; do not confuse with 121.5 or 126.7 MHz.
References
- TC AIM SAR 4.2 Notes 1, 3, 4
- TC AIM SAR 4.5
- RIC-21 6.3