|This report by Airspace4All presents an analysis of Electronic Conspicuity data gathered at the LAA Rally in 2019. The Executive Summary is presented below and the full 19 page report is available here:|
Electronic Conspicuity Data Collection at the LAA Rally 30 August to 1 September 2019
The LAA Rally 2019 was a 3½-day event attended by 743 different light aircraft (some 7.5% of the UK fleet). There were no gliders or balloons. Airspace4All took the opportunity to collect electronic conspicuity (EC) data to obtain a large sample snapshot of EC equipage and operation in GA aircraft. Pre-flight booking data, ATS logs and data from a receiving station in the exhibition area were merged to define the electronic signature of each aircraft.
Many aircraft had multiple devices: there were more devices than aircraft.
The transponder distribution correlated closely with the UK aircraft register and licensing database suggesting that these results are indicative of EC distribution in the GA sector.
Of the 66% of aircraft equipped with Mode S, 59% had Mode S only and 41% were also equipped with another system. Of those:
- There were no Mode A only and just 1% of aircraft had Mode C only.
- Just 4% had unregulated equipment as the sole system (FLARM and/or PAW).
- ADS-B Out was fitted to 15% of aircraft, most commonly with Mode S.
- Only 1% of aircraft were equipped solely with ADS-B.
- PAW was fitted to 21% of aircraft, most commonly in addition to Mode S.
- FLARM was fitted to 7% of aircraft, most commonly in addition to Mode S.
- PAW and PowerFLARM provide an ADS-B In capability
Mode S, as fitted in 66% of GA aircraft, can be seen by ATS radar and CAT aircraft TCAS systems but is not directly interoperable with other GA aircraft except that some EC devices include bearingless detection of Mode C and S.
ADS-B Out/In is fitted in 15% of GA aircraft which can see and be seen by each other and can be seen by a total of 18% of other aircraft with PAW and PowerFLARM which include an ADS-B In capability; a total GA ADS-B interoperability of 33%. In addition, these 33% of aircraft can also see ADS-B Out broadcast by most CAT aeroplanes and commercial helicopters.
GA ADS-B Out is not supported by ATS radars and is only partly interoperable with CAT TCAS systems because of the System Integrity Level (SIL). However, because 94% of GA ADS-B installations are in aircraft with Mode S, this is not a practical limitation today.
PAW is fitted to 21% of GA aircraft, which can see and be seen by each other and because PAW devices provide ADS-B In they can also see the 8% of other GA aircraft with ADS-B Out; a total GA interoperability of 29% plus ADS-B Out broadcast by most CAT aeroplanes and commercial helicopters.
PowerFLARM is fitted to 7% of GA aircraft which can see and be seen by each other and by the majority of cross-country gliders. Because PowerFLARM devices provide ADS-B In they can also see the 12% of other aircraft with ADS-B Out; a total interoperability of 19% plus most gliders and most CAT aeroplanes and commercial helicopters
33% of GA aircraft can see most CAT aeroplanes and large helicopters via ADS-B In either in discrete devices or using the functionality in PAW, PowerFLARM or other devices.
Clearly, two-way “see and be seen” is better than oneway “see” or “be seen” because it provides a more complete air picture to both aircraft in the equation. However, the diversity of the technologies in use provides a remarkable degree of interoperability between the 4 systems and between different categories of aircraft.
Key Points and Issues
- GA aircraft equipped with all 4 systems described are interoperable with almost all CAT aeroplanes and large helicopters and most gliders.
- Although ADS-B aircraft interoperability is some 33% achieved through diversity of devices, ADS-B ground stations can only see 15% of GA traffic.
- SIL level zero prevents ADS-B interoperability beyond GA systems.
- Unregulated devices are delivering a large proportion of ADS-B In functionality.
- Screening and range issues of portable ADS-B devices have not been analysed.
- Development of functionality in the regulated but particularly the unregulated sector is rapid and innovative.