Responses were received from 6 ANSPs, 8 airports, one aircraft operator and one national authority.
Q1. Are one runway, one frequency operations in use at aerodromes?
A slight majority of respondents indicated that they use some form of Triple One type operations with vehicle drivers able to transmit directly on the Tower frequency. In most other cases, drivers can transmit indirectly via ‘cross-coupling’. (See also Q3 below).
The most common reasons cited for not using Triple One type ops are:
- Lack of necessary communication infrastructure.
- The driver training burden in particular concerning the use of English as a single language.
- Perceived risks of distraction/’interference’ caused by drivers utilising the Tower frequency.
- There is no clear regulatory background (see ITU regulation vs ICAO and EAPPRI); moreover, there is a lack of provisions in the aerodrome rules for obligatory use of Air-Ground frequency by vehicles for runway operations.
Q2. On aerodromes with multiple runways, does each runway have its own assigned Tower frequency?
On aerodromes with multiple runways separate Tower frequencies are generally assigned for each parallel/independent runway but a common frequency is used for intersecting runway operations.
Q3. 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.
Except one, all respondents stated that vehicle drivers are at least able to monitor the Tower frequency to improve the situational awareness (SA) of drivers on the manoeuvring area, in particular on or near the runway(s). In the one instance where monitoring is not possible all vehicles o the manoeuvring area are fitted with a ‘squitter’ which enables their display on the controller’s A-SMGCS screen. In just over half of the cases drivers can also transmit directly on the Tower frequency for runway associated ground vehicle control messages, i.e. Triple One operations. For the majority of the remaining cases another dedicated frequency (typically UHF) is used for controlling vehicular traffic on the manoeuvring area. This can be ‘cross-coupled’ with the Tower frequency so that vehicle control messages (from the driver/ATC) can be heard by pilots.
Respondents were agreed that the ability of drivers to speak (and understand) an appropriate level of English is an essential requirement for the success of Triple One type operations. However, there is recognition that in some states this can be particularly challenging and burdensome. It is this requirement/qualification and associated human factors issues that is often cited as a main impediment to the adoption of Triple One at some aerodromes.
Q4. Describe the training requirements for drivers who require access to runways
Except in one case where ATC is responsible, manoeuvring area driver training (and examination, licensing etc) is the responsibility of the aerodrome operator often with an ATC input. All aerodromes issue licences, permits etc to drivers who have passed the necessary test/examination to drive on the MA. Some aerodromes operate a tiered system of driver permits covering apron, manoeuvring area and runway operations. The standards/requirements for those drivers who need to access the runway are more stringent than those who only require access to the apron and/or the MA. One airport has invested in a aerodrome driver simulator which has improved training flexibility, effectiveness and efficiency. The validity periods of aerodrome driving permits vary. Refresher and/or re-examination is provided on an annual or at least 2-yearly basis depending on the type and coverage of permit/licence.
Q5. What are the limitations of use of the Tower frequency by drivers, e.g. runway crossings, accessing the runway for inspections/work etc?
As per ICAO and EAPPRI guidance, where practised, Triple One type operations are restricted to drivers who need to access or cross runways. Drivers who may need only to cross a runway might not necessarily have to comply with the same high driving standards as those who need to access the runway and crossings are conducted using a frequency other than the Tower frequency (but typically cross - coupled with it) under the authority of the Tower Controller.
Q6. 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.
Other than a very occasional mistaken/’nuisance’ call, the respondents reported that Triple One has not caused any significant safety issues. Indeed, most report that, where used, Triple One improves overall safety on and around the aerodrome because of the enhanced SA it provides to all parties; the benefits outweigh any perceived risk associated with overlapping pilot/controller/driver transmissions, interference etc.
English language proficiency for drivers is a key consideration and the lack of it is often the main factor holding back the adoption of Triple One.
In some cases, local runway safety teams (LRST) monitor and review the application of Triple One to ensure its continued effectiveness.
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