Radio Communication Technical Information

The issues surrounding ground-to-air radio communications by certificated FAA pilots flying drone aircraft are complicated.

It is in the interest of safety and the coordination of ground-based aircraft and manned aircraft operating above a scene to establish communications to maximize aviation safety.

There are two sections of FCC regulations that appear to allow for such communications. The process for application is murky and without a perfect solution as I write this.

FCC Frequency Information

  • 122.75 – Airplane (Air-to-Air)
  • 122.85 – General Communications (Air-to-Ground)
  • 122.90 – SAR training (Air-to-Ground)
  • 123.025 – Helicopter (Air-to-Air)
  • 123.10 – Actual SAR missions (Air-to-Ground)

It is recommended that if there are any helicopters operating in the area that the UAS team establish communications with the helicopter using 123.025 to coordinate airspace.  See this for information.

If communications with the helicopter or low flying aircraft can not be established, the UAS PIC should land immediately.

FCC License Application

This is information I have previously published regarding what seems to be the logical application process and form for UAS ground-based pilots to obtain the appropriate FCC license. See this post to determine if you should apply to use a handheld aviation band radio. You can apply online and immediately receive your radio license.

Aviation Handheld Radios

These aviation radios will allow you to communicate with aircraft above within a limited distance given the low power of all handheld radios.

FCC Regulations

The first is 47 CFR Part 87 Subpart M. 

§ 87.371 Scope of service.

“Aeronautical search and rescue land and mobile stations must be used only for communications with aircraft and other aeronautical search and rescue stations engaged in search and rescue activities. Aeronautical land search and rescue stations can be moved for temporary periods from a specified location to an area where actual or practice search and rescue operations are being conducted.”

§ 87.375 Frequencies.

(a) The frequency 123.100 MHz is available for assignment to aeronautical search and rescue stations for actual search and rescue missions. Each search and rescue station must be equipped to operate on this frequency.

(b) The frequency 122.900 MHz is available for assignment to aeronautical search and rescue stations for organized search and rescue training and for practice search and rescue missions.

(c) The frequencies 3023.0 kHz and 5680.0 kHz are available for assignment to aircraft and ship stations for search and rescue scene-of-action coordination, including communications with participating land stations. Ship stations communicating with aircraft stations must employ 2K80J3E emission.

The second is 47 CFR Part 87 Subpart H.

§ 87.237 Scope of service.

(a) The communications of an aeronautical multicom station (multicom) must pertain to activities of a temporary, seasonal or emergency nature involving aircraft in flight. Communications are limited to directing or coordinating ground activities from the air or aerial activities from the ground. Air-to-air communications will be authorized if the communications are directly connected with the air-to-ground or ground-to-air activities described above. Multicom communications must not include those air/ground communications provided for elsewhere in this part.

(b) If there is not unicom and an applicant is unable to meet the requirements for a unicom license, the applicant will be eligible for a multicom license.

(1) The multicom license becomes invalid when a unicom is established at the landing area.

(2) Multicoms must not be used for ATC purposes other than the relay of ATC information between the pilot and air traffic controller. Relaying of ATC information is limited to the following:

(i) Revisions of proposed departure time;

(ii) Takeoff, arrival flight plan cancellation time;

(iii) ATC clearances, provided a letter of agreement is obtained from the FAA by the licensee of the multicom.

(3) Communications by a multicom must be limited to the safe and expeditious operation of private aircraft, pertaining to the conditions of runways, types of fuel available, wind conditions, weather information, dispatching or other information. On a secondary basis, multicoms may transmit communictions which pertain to efficient portal-to-portal transit of an aircraft such as requests for ground transportation, food or lodging. 

This section includes the use of 122.85 or 122.90 MHz.

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