EC Trials

One of the portable EC units in situ

Traffic Displays at general aviation airfields would be practical, help mitigate the risk of potential mid-air collisions, help to reduce airspace infringements and check whether people were following local traffic regulations.

The airfields’ Flight Information Service Officers/Air/Ground Operators were trained up to be allowed to broadcast generic traffic information and warnings if aircraft appeared to be approaching controlled airspace, but they weren’t allowed to pass specific traffic information or aircraft deconfliction instructions, that remained firmly the preserve of controllers with radar ratings. While they weren’t allowed to pass traffic information in a form relative to the direction of travel,“you have traffic in your 2 o’clock”, geographic locations were permitted, such as “there is traffic in the vicinity of Irlam VRP”.

The towers’ new traffic display systems were relatively low-cost – about three percent of other broader systems, so installation is well within the means of virtually all general aviation airfields. As well as the ground stations, Airspace4All provided 50 commercially available portable ADS-B transceivers to make more local aircraft ‘visible’ to the displays.

Data was fed into a standard Windows 10 computer running a cost-free Virtual Radar Server so that the aircraft could be plotted on a map on a conventional low reflection PC monitor. The main cost was an ADS-B ground receiver and a receiver/aerial (£1499 at the time). The setup was reasonably straightforward, only requiring a small amount of IT expertise.

Then it was down to the daily business

at the airfields with the operators providing enhanced advice, information and warnings as appropriate. To monitor the trial’s progress, the operators provided daily and monthly feedback which produced some additional and surprising results ranging from pilots mistaking runways or heading for controlled airspace, to others not being quite where they thought they were… One report, for example, said: “G-XXXX reported six miles west when in fact he was showing as three miles south-west. One minute later [the] aircraft was downwind so the pilot position report was definitely wrong and the ADS-B data was proved correct and accurate”.

Clearly most of the operators liked the system and wanted to keep the kit after the trial. Essentially, they said the displays were safe, reliable, very accurate and not a distraction. Many added that it was a valuable additional tool that provided positive safety benefits to aircraft. The trial did, though, require commitment from airfield management and staff to provide the installation, training and supervision, and an openness to change.

Their comments were summed up well by one who said: “Having been a FISO for some 20 years it has been nothing but a positive. It enables me to provide a much better service as a FISO giving me a tool to enhance my own situational awareness. Rather than relying solely on (often inaccurate and woolly) position reports, I can now confidently know where aircraft are and identify relevant traffic information and assist pilots in avoiding conflict”.

And it seems the pilots liked the system too; interestingly, the trial has so raised general awareness of ADS-B in the wider

Goodwood's tower with ADS-B aerial on the left

general aviation community that there’s been a noticeable increase in the number of people fitting their own ADS-B units at the airfields where the trials took place. There were, of course, some issues including poor cockpit positioning of the portable ADS-B units masking the aircraft’s signal, pilots forgetting to switch them on, lack of charge, not switching off on the ground resulting in ‘clutter’ on the traffic display screen and using a device programmed with information for the ‘wrong’ aircraft. In summary, the trial’s report said that overall the ADS-B Traffic Display was found to be an effective and economic means of providing accurate and timely traffic information to aircraft at and around a GA airfield. Its installation was welcomed by ATS and AGCS operators.

A recommendation added that ADS-B position data should be usable/ treated by air traffic services as exactly equivalent to a pilot position report. In the absence of a pilot position report (if the aircraft isn’t on frequency, for example) then the position date is all that ATS has to pass on as traffic information and even with pilot position reports the ADS-B position is usually more up to date and often more accurate. So, with phase one concluded, where does ADS-B in relation to general aviation airfields go from here? At present, all of the results are being examined and further trials are expected this year.

If you’d like to read the latest official guidance to on setting up ADS-B in general aviation aircraft you’ll find it in AIC (Y141/2019) on the NA (

TS website



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