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Uncontrolled Aerodromes - Communications

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Definition

An uncontrolled aerodrome is an aerodrome without a control tower, or one where the tower is not in operation.

Discussion

There is no substitute for alertness and situational awareness while in the vicinity of an uncontrolled aerodrome. It is essential that pilots look out for, and be aware of, other traffic and exchange relevant information when approaching or departing an uncontrolled aerodrome. To achieve the greatest degree of safety, it is essential that all radio-equipped aircraft monitor and transmit on a common designated frequency and follow the appropriate reporting protocols. Designated frequencies can include a Mandatory Frequency (MF) or an Aerodrome Traffic Frequency (ATF) which will be published in the Flight Supplement or on an approach chart for the airport in question. In the absence of a specified MF or ATF frequency, the country specific frequency for use at uncontrolled airports should be used. In the UK, this is referred to as "SafetyCom" callsign "traffic" is currently assigned the use of VHF frequency 135.475 MHz. In Canada, the published Universal Communications (UNICOM) frequency should be used in the absence of a published MF or ATF frequency or, if there is no UNICOM, 123.2 MHz.

Communications at Uncontrolled Aerodromes

There are different levels of service provision for air to ground radio communications at uncontrolled aerodromes. These range from no service to provision of an Air/Ground radio service to an Aerodrome Flight Information Service (AFIS) or Flight Service Station (FSS) with the nomenclature varying by country. The procedures associated with the various levels of service are as follows:

  • No ground services: As indicated above, a common traffic advisory frequency is in use at aerodromes that do not have a specific frequency assigned. In the UK it is currently 135.475MHz whilst in Canada, 123.2 is used. The frequency is normally used within 5-10 NM and/or up to 1000 ft above the traffic circuit at the aerodrome in question but this is variable by both airport and country. Aircraft should announce their position and intentions at the normal reporting points using the callsign “traffic” after stating the name of the aerodrome at which they are operating. For example "Kingston Traffic".
  • Air/Ground radio service: Air/Ground (A/G) radio is the most basic form of radio ground station you will encounter at an aerodrome. The operator of an air/ground radio may provide traffic and weather information to pilots operating on and in the vicinity of the aerodrome. Such traffic information is based primarily on reports made by other pilots. The safe conduct of the flight remains the pilot’s responsibility as the radio operator has no power to issue clearances or instruct aircraft either in the air or on the ground.
The normal callsign is “Radio” after the station name. When operating in the A/G environment, the basic principle is that aircraft announce their position and separate themselves from other aircraft in accordance with the Rules of the Air and any published aerodrome procedures. Only carry out a manoeuvre (such as taxiing, take-off or landing) if you are satisfied if it is safe to do so and will not conflict with other traffic.
  • AFIS or FSS: The Aerodrome Flight Information Service (AFIS) and the Flight Service Station (FSS) are essentially a Flight Information Service provided at an aerodrome. It is a higher level of service than A/G radio; however it remains fundamentally a source of information rather than control. Generally, they will pass more comprehensive information on traffic than an A/G station would. In the UK, AFIS do issue mandatory instructions to aircraft and vehicles on the ground, up until aircraft pass a runway holding point. In Canada, FSS will accept flight plans and can relay IFR clearances to aircraft on the ground or in flight. The normal callsign for a FFS is "radio", for example "Resolute Radio" whilst for an AFIS it is “Information”, for example “Duxford Information”. In both environments, it remains a pilot responsibility to be satisfied that every action is safe and to announce their position and intentions while operating at the aerodrome.

Communication Procedures and Protocols

Communications procedures vary from country to country and also can vary in accordance with the level of service provisions at the aerodrome in question. The following lists provide reporting protocols for most situations.

General

  • Maintain a listening watch on the "appropriate frequency" (MF, AFIS, ATF, G/A, or UNICOM ) specified for use in the aerodrome area
  • Report the pilot-in-command’s intentions before entering the manoeuvring area

Visual Flight Rules (VFR)

The following procedures apply when flights are conducted under Visual Flight Rules (VFR).

Departure

  • Before moving onto the take-off surface, report the pilot-in-command’s departure intentions on the appropriate frequency. If a delay is encountered, broadcast intentions and expected length of delay, then rebroadcast departure intentions prior to moving onto the take-off surface
  • Before takeoff, ascertain by both radio and by visual observation that there is no likelihood of collision with another aircraft or a vehicle during takeoff
  • After takeoff, report departing from the aerodrome traffic circuit, and maintain a listening watch on the appropriate frequency until clear of the area

Arrival

  • Before entering the aerodrome area (and, where circumstances permit, at least five minutes before entering the area), report the aircraft’s position, altitude and estimated time of landing and the pilot-in-command’s arrival procedure intentions on the appropriate frequency
  • Report when joining the aerodrome traffic circuit, giving the aircraft’s position in the circuit
  • Report when on downwind leg, if applicable
  • Report when on final approach
  • Report when clear of the surface on which the aircraft has landed

Continuous Circuits

  • Report when joining the downwind leg of the circuit;
  • Report when on final approach; stating the pilot-in-command’s intentions
  • Report when clear of the surface on which the aircraft has landed

Flying Through an MF Area

  • Report before entering the MF (where circumstances permit, at least five minutes before entering the area), giving the aircraft’s position and altitude and the pilot-in-command’s intentions
  • Report when clear of the MF or ATF area

NOTE: In the interest of minimizing possible conflict with local traffic and minimizing radio congestion on the MF or ATF, pilots of en-route VFR aircraft should avoid passing through MF or ATF areas whenever practical

Instrument Flight Rules (IFR)

The following applies to an aircraft operating under Instrument Flight Rules (IFR) in both Visual Meteorological Conditions (VMC) and in Instrument Meteorological Conditions (IMC).

Departure

The pilot-in-command of an IFR aircraft who intends to depart from an uncontrolled aerodrome shall:

  • Obtain an ATC clearance if in controlled airspace
  • Report the planned departure procedure and intentions on the appropriate frequency before moving on to the runway
  • Ascertain by radio on the appropriate frequency and by visual observation that no other aircraft or vehicle is likely to come into conflict with the aircraft during takeoff
  • Maintain a listening watch:
    • during takeoff from an uncontrolled aerodrome
    • after takeoff from an uncontrolled aerodrome for which a MF has been designated, until the aircraft is beyond the distance or above the altitude associated with that frequency
  • As soon as possible after reaching the distance or altitude associated with the MF, the pilot-in-command shall communicate with the appropriate ATC unit or a ground station on the appropriate en-route frequency
  • Where IFR departures are required to contact an IFR control unit or ground station after takeoff, it is recommended that, if the aircraft is equipped with two radios, the pilot should also monitor the MF during the departure

Arrival

The pilot-in-command of an IFR aircraft who intends to conduct an approach to or a landing at an uncontrolled aerodrome shall report on the appropriate frequency:

  • The pilot-in-command’s intentions regarding the operation of the aircraft
  • Five minutes before the estimated time of commencing the approach procedure, stating the estimated time of landing
  • When commencing a circling manoeuvre
  • As soon as practicable after initiating a missed approach procedure

They will also report the aircraft’s position:

  • When passing the fix outbound, where the pilot-incommand intends to conduct a procedure turn or, if no procedure turn is intended, when the aircraft first intercepts the final approach course
  • When passing the final approach fix or three minutes before the estimated time of landing where no final approach fix exists
  • On final approach
  • Report when clear of the surface on which the aircraft has landed

In addition to these requirements, pilots operating aircraft under IFR into an uncontrolled aerodrome, when the weather conditions at the aerodrome could permit VFR circuit operations, are expected to approach and land on the active runway that may be established by the aircraft operating in the VFR circuit unless that runway is not suitable for the IFR aircraft. Pilots operating aircraft under IFR at an uncontrolled aerodrome do not establish any priority over aircraft operating under VFR at that aerodrome. Should it be necessary for the IFR aircraft to approach and/or land on a runway contrary to the established VFR operation, it is expected that appropriate communications, between pilots or between pilots and the air-ground facility, will be effected in order to ensure there is no traffic conflict.

Related Articles

Further Reading

UK CAA

Transport Canada

FAA