Use of aerodrome Tower VHF frequency by vehicle drivers involved in runway operations

Synopsis

To enhance situational awareness on aerodromes, drivers of vehicle operating on or in very close proximity to runways sometimes transmit movement control messages (e.g. requests to cross/enter runways) on the assigned VHF ATC Tower/Aerodrome Control air to ground frequency rather than a dedicated ground-ground frequency. This practice is in line with guidance in ICAO Doc 9870, Manual on the Prevention of Runway Incursions, and the European Action Plan for the Plan of Runway Incursions (EAPPRI).

However, it has been noted that using the frequency for these purposes may contravene International Telecommunications Union (ITU) regulations on the use of air to ground radio frequencies.

Note: It is known that at some aerodromes the use of the one runway, one frequency principle has been extended to include the use of one language (i.e. English); this is sometimes referred to as «Triple One»: One Runway, One Frequency, One Language.

ICAO Provisions

ICAO Doc, 9870, Manual on the Prevention of Runway Incursions
4.2.6 "All communications associated with the operation of each runway (vehicles, crossing aircraft, etc.) should be conducted on the same frequency as utilised for the take-off and landing of aircraft". Further details are provided in Appendix A, §1.6.

European Action Plan for the Prevention of Runway Incursions (EAPPRI)

The EAPPRI also provides slightly more elaborate guidance in Appendix A Communications Guidance, namely:

"Runway Frequency: It is recommended that communications for all operations on a runway (landing, departing, crossing aircraft, vehicles crossing and runway inspections etc.) take place on the VHF frequency assigned for that runway; this will help to maintain high levels of situational awareness. To accommodate vehicles that are equipped with UHF radios only, frequency 'coupling' should be employed to ensure that all UHF communications associated with runway operations are simultaneously transmitted on the appropriate VHF frequency (and vice versa). When using RTF frequency coupling, controllers (and drivers) need to be mindful of 'clipped' transmissions, where the beginning or end of the transmission is not broadcast/received.

Concerns about runway frequency congestion due to drivers using VHF can be alleviated by treating every use of the runway as a planned traffic movement, and keeping detailed discussions e.g. FOD descriptions, for another frequency."

ITU Regulations

The use of frequencies between 117,975 – 137 MHz for the Aeronautical Mobile Route Service AM(R)S is determined in the ITU Radio Regulations.

Radio Regulations 2012, ARTICLE 43 Special rules relating to the use of frequencies, (43.1) §1: "Frequencies in any band allocated to the aeronautical mobile (R) service and the aeronautical mobile-satellite (R) service are reserved for communications relating to safety and regularity of flight between any aircraft and those aeronautical stations and aeronautical earth stations primarily concerned with flight along national or international civil air routes."

The ITU Radio Regulations defines communication of AM(R)S on VHF as communication between aircraft (air/air) or between aircraft and ground (air/ground). No ground/ground – communication should take part on VHF – frequencies between 117,975 – 137 MHz.

Analysis

The use of a single VHF frequency for air and ground runway operations to improve situational awareness and safety has been in use for a number of years. Although the one runway, one frequency principle allows the driver to transmit on the Tower frequency these operations also bring potential risks such as simultaneous driver/controller/pilot transmissions and 'stuck' microphones. However, there is no recorded evidence that this mode of operation – or its alternative of 'cross-coupling' vehicle UHF frequencies with the Tower VHF frequency – has caused safety concerns. The proviso is that drivers must listen out before transmitting and that drivers exercise care in the use of the single frequency as per the ICAO and EAPPRI guidance.

In the strictest sense, the ITU regulations, if taken at face value, do not permit one runway, one frequency type operations. However, the spirit of the regulations is aimed at the misuse of an air to ground frequency for ground to ground communications that that have no relation to air operations. For instance, it would be inappropriate to use an allocated air-ground frequency for use on the ramp or apron, but in the case where the frequency is used for specific and very tightly defined air operations – such as those involving runway operations when pilots will also be the (silent) recipients of drivers' transmissions – then it is arguable that such use is bona fide and does not amount to an abuse of the frequency.

Note: To gain the maximum operational safety benefit form the one runway, one frequency principle, it is generally considered essential that it is supplemented with the one language element (i.e. the use of English). This means that if "Triple One" is adopted all vehicle drivers who need to have access to the runway must be proficient in aviation English/standard phraseology. The alternative use of mixed languages on the single frequency poses obvious communications problems which may negate the advantages of using one frequency for runway related operations.

Support Requested

The purpose of this RFS message is to determine the extent of the use of one runway, one frequency operations with a view to taking appropriate follow-up action as necessary.

• Air navigation service providers and aerodrome operators, are requested to provide details of one runway, one frequency and/or «Triple One» type operations:
  1. Are one runway, one frequency operations in use at aerodromes? If yes, please answer the questions 2 – 6 below. If no, please explain why not (e.g. because they contravene ITU regulations), describe how vehicles that need to access/cross runways are controlled and answer any of the questions below as appropriate.
  2. On aerodromes with multiple runways, does each runway have its own assigned Tower frequency?
  3. Are all vehicle drivers who need to access the runway capable of: a) Monitoring the Tower frequency?
     b) Transmitting directly on the Tower frequency?
     c) Transmitting on the Tower frequency indirectly, i.e through 'cross-coupling' another ground-ground UHF frequency with the Tower frequency?
     d) Speaking an appropriate level of aviation English.
     
  4. Describe the training requirements for drivers who require access to runways.
  5. What are the limitations of use of the Tower frequency by drivers, e.g. runway crossings, accessing the runway for inspections/work etc?
  6. Describe any operational difficulties (e.g. languages, technical problems) or safety related occurrences when the use of one runway, one frequency/ «Triple One» type operations by drivers has caused interference/interruption with controller/pilot transmissions.
• Aircraft operators are invited to note the subject and share their experiences with the issue described.