One of the key requirements for the safe deployment of vehicles airside, on manoeuvring areas shared with aircraft, is that their drivers (or their front seat colleagues) are competent in RTF communication with ATC. Airport Authorities usually have overall responsibility for setting and monitoring standards, but the agency operating a vehicle has direct responsibility for ensuring that ATC communications with their vehicle is of a standard which will preclude any contribution to diminished safety standards for aircraft. Whilst some vehicles will be operated directly by the airport authority, most will be operated by various service providers. The chance of disaster is at its greatest when the possibility exists of an aircraft at speed on a runway, during the take off or landing roll, encountering ground vehicles. One national survey showed that in 2007, 26% of recorded runway incursion incidents involved vehicles and the majority were not unintended errors by ATC but unintended errors by vehicle drivers.
Who are the Drivers?
Apart from Airport Authority personnel who may fulfil many different roles including the very specialist RFFS, it is likely that airside drivers will also include persons working airside in connection with:
- Aircraft Maintenance;
- Aircraft Ground De/Anti-Icing;
- Aircraft and Passenger Handling;
- Aircraft Catering;
- Aircraft Cleaning;
- Aircraft Refuelling;
- Passenger and Crew transport;
- Visiting vehicles requiring escort.
Where Are They Driving?
All airport operators should have a system for issuing airside driving permits; this should include a process for validating competency in the effective use of ATC radio communications. Within the aircraft manoeuvring area, there are usually two types of region: those for which ATC permission is required for access and those for which permission is not required. This article addresses the risk to aircraft safety attributable to the first of these regions.
The Key Elements of Acceptable ATC Radio Communication for Vehicle Drivers
- At larger airports, it is usual to find different parts of the airport controlled by ATC using different radio frequencies, often with different radio call sign endings. A call sign ending in “Tower” (TWR) usually indicates a radio frequency used to control at least one active (in use) runway; a call sign ending in “Ground” (GND) usually indicates that an active (in use) runway is not being controlled.
- Speak clearly and at a moderate speed, especially if the speaker has marked regional or non-native accent.
- Always listen before starting a transmission and be aware that there may be a short gap between a transmission by other traffic or ATC and the corresponding reply.
- Press the radio transmit switch before beginning to speak and do not release it until a transmission is finished, otherwise it may be ‘clipped’ and an important part of the content lost.
- Know the airport layout and the location and designation of all runways, taxiways and holding points.
- Find out before setting out which runways are in use and the location of any “work in progress” or taxiway closures which may affect usual routes.
- Strictly adhere to vehicle speed limits; ATC will assume this if they need to amend a current clearance.
- Use marked roadways where available
- If in any doubt about an ATC instruction, obtain a repeat by saying “Say Again" (or “Say Again all before/after/between…”). Do not proceed beyond the previous clearance limit until a response has been obtained and understood.
- Ensure that all ATC Clearances are read back in full before proceeding.
- Remember the designated radio call sign for either the driver or the vehicle and:
- listen out for it at all times
- use it to identify each transmission made.
- Listen to aircraft/ATC communications and where possible, use the information acquired to build up a mental map of what else is moving - or about to be moving - in the area in which you are at present, or where you are about to proceed. This is called maintaining 'situational awareness' and is important for flight crew too.
- If the vehicle being driven has an automatic position transmitter fitted which allows ATC to see its position on a remote display, then this must be switched on whenever this is required.
- If a vehicle driver becomes uncertain of his/her position, the vehicle should be stopped immediately and ATC informed. Further movement should await ATC instructions.
- If the occupants of a vehicle operating under ATC Control need to work outside it, then they must have a means of hearing calls from ATC - a vehicle loudspeaker or portable radios - and these must be audible even at the high noise levels that are likely to be experienced.
- Be aware of local radio failure procedures and be prepared to recognise the signs that this has occurred - whether wholly or only in respect of vehicle reception or (apparently) vehicle transmissions.
- Review airport driver training materials for your specific airport regarding airport signage and markings, hot spot locations, and construction.
It is important that radio communications are concise so that the amount of transmission time is minimised, but also even more important that they are fully understood. In many cases, single words are used which are equivalent to a phrase. Sometimes, even single words which are not commonly encountered in everyday use are used by ATC as important instructions. Also, where letters or numbers have to be spoken individually eg “Hold at C12” then it is important that the international radio telephony alphabet is used.
Many airports have more than one runway and if so, it is important to be aware which runways are in use or ‘active’. It is always necessary to obtain a specific clearance to cross any runway, active or inactive.
Persons authorised to drive and/or operate ATC radio communications in vehicles which tow aircraft should be very carefully selected and trained by their employers, with special reference to any restricted visibility from the vehicles used and their awareness of the size of aircraft types which may be towed. The potential effect of not complying with ATC clearances when towing aircraft, or if the link between the towing vehicle and the aircraft nose landing gear fails, is clearly much greater than for a vehicle on its own.
Low Visibility Procedures (LVPs)
An airport which has approved procedures to continue with aircraft movements in low forward visibility will have a formal set of procedures which apply whenever Low Visibility Procedures (LVP) are declared to be in force. Typically, all non-essential airside vehicular traffic will be prohibited and remaining traffic will be required to drive within reduced speed limits and use different runway entry holding points. In addition, taxiway and runway lighting will be in use which may not necessarily be the case otherwise during daylight.
The most important aspects of driving under ATC control are:
- to follow all clearances as given, and
- to maintain situational awareness.
Additionally, it is part of the driver's responsibility to be observant and to make radio reports to ATC of:
- any apparent external abnormalities in respect of an aircraft in the vicinity;
- bird or other wildlife activity which may be unknown to ATC and apparently hazardous to aircraft;
- any significant FOD sighting;
- any other hazard to aircraft or personal safety which is seen from the vehicle.
Escorted Vehicles not in Radio Contact with ATC
If appropriate procedures have been agreed with ATC, it may be permissible for a radio equipped vehicle driven by a suitably authorised permit holder to escort a visiting vehicle within the ATC-controlled zone. Such arrangements carry a heavy responsibility upon the escorting driver to ensure that the driver of the escorted vehicle has been properly briefed and to monitor the position of the other vehicle at all times to ensure both vehicles comply with ATC clearances. This particularly applies to position reports which will need to be made only when the whole ‘convoy’ is in compliance.
Local Runway Safety Teams (LRST)
There will often be a Local Runway Safety Teams (LRST) at an airport. If there is, it will usually be run by the Airport Authority and attended by ATC. It exists to monitor issues which may affect runway safety and is therefore very concerned with runway crossings by vehicles and situational awareness of their drivers, both of which are heavily dependent upon high standards of radio communication. It is there both to receive input and to help co-ordinate any action which may be needed to deal with problems and issue alerts.
- UK CAA A Reference Guide to UK Phraseology for Aerodrome Drivers
- An Airside Driver's Guide to Runway Safety: Airservices Australia, 3rd edition, June 2012.
- FAA Guide to Ground Vehicle Operations, FAA.
- European Action Plan for the Prevention of Runway Incursions, Appendix A - Communications Guidance
- European Action Plan for the Prevention of Runway Incursions, Appendix C - Airside Vehicle Driver Training
- ICAO Doc 9870 App A - Communications Best Practice
- ICAO Doc 9870 App D - Airside Vehicle Driving Best Practices
- ACI Airside Safety Handbook, 4th edition (2010)
- AC 150/5210-20A: Ground Vehicle Operations to include Taxiing or Towing an Aircraft on Airports, FAA, September 2015
- Network Manager Safety Study: The Impact of Airside Drivers on Runway Safety, EUROCONTROL, August 2015.