Helicopter IFR Technique: Communications – A Little Help from Our Fixed-Wing High Flyers
Helicopters operate at relatively low altitudes, where terrain, distance, and the curvature of the earth can make line-of-sight radio communication challenging. Being unable to reach ATC is not only frustrating; it can affect mission accomplishment and flight safety.
It was eye-opening the first time ATC relayed a message to our helicopter through a commercial airliner flying at approximately 30,000 feet. We were about 100 miles offshore, and the message contained important information from our operational controllers concerning an active rescue case.
The communication through the airliner was clear, and the fixed-wing crew genuinely seemed to appreciate the opportunity to help. After that exchange, I never hesitated to initiate a relay through a high-flying aircraft when circumstances warranted it.
A relay can be initiated on the assigned ATC frequency. If you cannot reach the controller but can hear other aircraft communicating with the facility, wait for an opening and make a concise request:
“Any aircraft on Seattle Center, NXXXAB, request radio relay.”
Once another aircraft responds, provide the message you need passed:
“NXXXAB, twenty miles west of Astoria, one thousand five hundred. Unable to reach Seattle Center on one two four point two.”
The assisting aircraft might transmit:
“NXXXAB, Airliner 123. Seattle Center advises contact them on one two eight point three.”
“Seattle Center, Airliner 123, relay from NXXXAB. They are twenty miles west of Astoria at one thousand five hundred and unable to reach you on one two four point two. Do you have another frequency for them?”
After receiving the controller’s response, the aircraft can pass it back to you:
A response might be simply:
“One two eight point three, NXXXAB. Thanks for the help.”
A relay can also be used when ATC needs to pass a clearance or instruction to an aircraft below its radio coverage. For example:
“NXXXAB, Airliner 123, Seattle Center advises climb and maintain four thousand and contact Center on one two five point eight.”
Because the message contains an altitude assignment and frequency change, read back both:
“Climb and maintain four thousand, one two five point eight, NXXXAB.”
The assisting aircraft can then relay your readback to the controller, closing the communication loop.
If you cannot reach ATC or another aircraft on the assigned frequency, a relay may also be initiated on guard:
“Any aircraft on guard, Rescue Helicopter XXXX, request assistance with a relay to Seattle Center.”
Because 121.5 is the international emergency frequency, transmissions on guard should be limited to situations in which operational necessity or safety warrants its use. Keep the initial call short, then move to another frequency if practical.
Once another aircraft answers, identify your position, altitude, the facility you are trying to reach, and what you need:
“Rescue Helicopter XXXX, sixty miles northwest of Portland at five hundred feet. Unable to contact Seattle Center. Request relay to Center for an IFR pickup to Portland International.”
Radio relays are also useful for passing operational information when a helicopter is beyond the direct communication range of its shore-based command center. In those cases, ATC may serve as an intermediary and use another aircraft to bridge the final gap—just as it did for us 100 miles offshore.
A relay works best when each transmission contains only the information necessary to solve the immediate problem. Identify who you are, where you are, whom you are trying to reach, and what you need. If a clearance or instruction is passed through another aircraft, listen carefully and provide the same readback you would give ATC directly.
The aircraft overhead may be traveling in a different direction, at a different speed, and for an entirely different purpose. For a few minutes, however, its altitude and radio coverage may make it an important member of your crew.