Electronic Conspicuity Mandate Consultation 14 Jul - 22 Sep 2026

Electronic Conspicuity Mandate Consultation 14 Jul – 22 Sep 2026

The CAA’s EC mandate consultation – key points

The Civil Aviation Authority (CAA) has decided that general aviation (GA) aircraft should be mandated to use electronic conspicuity (EC) when flying in UK airspace.

The EC technology that will be required under the mandate is Automatic Dependent Surveillance – Broadcast (ADS-B).

The CAA is currently consulting on its proposed approach to an EC mandate in UK sovereign airspace, and how any future requirement should be designed and implemented.

In due course, the law will be changed to require all general aviation aircraft including sailplanes to use the CAA’s choice of EC technology when flying in UK airspace.

The CAA are proposing that following the change of law, there will be a two-year implementation period to provide time for aircraft owners to purchase the necessary EC equipment using their own funds.

This BGA guidance aims to inform glider pilots ahead of them submitting individual responses to the CAA consultation before the consultation closing date of 22nd September 2026.

The CAA’s EC mandate consultation can be viewed here.

About Electronic Conspicuity

Electronic Conspicuity (EC) is an umbrella term for the technology that can help pilots, unmanned aircraft users and air traffic services be more aware of what is operating in surrounding airspace. Here are some brief explanations of regularly used EC terminology.

ADS-B. Automatic Dependent Surveillance–Broadcast (ADS-B) is an aviation surveillance technology and form of electronic conspicuity in which an aircraft determines its position via Global Positioning System (GPS) satellite navigation or other sensors and periodically broadcasts its position and other related data, enabling it to be tracked. The information can be received by suitably equipped ground-based – including air traffic control – or satellite-based receivers as a replacement for Secondary Surveillance Radar (SSR). Unlike SSR, ADS-B does not require an interrogation signal from the ground or from other aircraft to activate its transmissions. ADS-B can also receive ADS-B transmissions from other ADS-B equipped aircraft to provide traffic situational awareness. . ADS-B is “automatic” in that it requires no pilot or external input to trigger its transmissions. It is “dependent” in that it depends on data from the aircraft’s navigation system to provide the transmitted data.

ADS-L. The European Aviation Safety Agency (EASA) has introduced the concept of ADS-L (ADS-B Light). Originally designed for the surveillance of crewed aircraft with airspace also occupied by uncrewed air systems (UAVs), as required by Article 6005 of the Standardised European Rules of the Air (SERA), ADS-L led to the creation of two standards: networked and broadcast. Each standard offers unique benefits and addresses different safety aspects, contributing to a comprehensive EC ecosystem. With the increasing complexity of the EC landscape, interoperability becomes crucial. This process involves allowing different EC systems (e.g. FLARM, PilotAware, ADS-B, etc) to communicate with each other to improve their overall effectiveness. Interoperability can be achieved through ground stations that rebroadcast or relay signals (this includes mobile networks such as 4G), multi-function in-cockpit devices or a combination of these.

Mode S is a Secondary Surveillance Radar (SSR) transponder process that allows selective interrogation of aircraft according to the unique 24-bit address assigned to each aircraft.

Mode-S Extended Squitter (ES). Mode S transponders automatically send periodic burst transmissions called “squitters”. These transmissions are self-generated and are not in response to interrogations from a secondary surveillance radar (SSR) system. The information sent in these burst transmissions, which require the mode S device to have an input from an appropriate GPS input, serves several purposes including Automatic Dependent Surveillance Broadcast (ADS-B) which provides an aircraft’s identification, GPS position, projected aircraft trajectory and navigation system status to allow controllers where equipped to do so to accurately track the aircraft.

Consultation questions – response guidance

It is important to respond to the CAA consultation questions with your views using your own words. Please try to avoid cut and paste responses.

We refer to some technical issues within our guidance below. Whilst we make no apology for highlighting that level of important detail, we do recognise that some glider pilots may find some of it difficult to understand and/or uninteresting. You could respond in those cases by noting that you have read the full BGA response information that has been developed by subject matter experts, and that you fully support it. You might also wish to express your concern that the mandate as proposed is likely to be an expensive and embarrassing failure for the UK government.

CAA consultation questions are in italics below followed by related BGA information/comments.

CAA consultation question. The CAA’s proposal is that the EC Mandate should apply to all civil general air traffic that is not already required to carry and use ADS-B equipment, operating below FL100 in UK sovereign airspace, subject to the exceptions for military and state aircraft and VLOS operations described in this chapter. Do you agree with that proposal?

No. The BGA needs no convincing that air-to-air EC can reduce the risk of mid-air collisions through enhanced situational awareness and conflict alerting. Gliding was the first GA sector to equip with EC devices and has seen a coincident drop in the number of mid-air collisions which we attribute at least in part to the carriage of FLARM. The BGA believes that the proposal to mandate all GA aircraft to equip with ADS-B is highly inappropriate. The following points highlight why.

It will be effective only for GA-GA/UAV collisions, because ADS-B signals will not be processed by a current Traffic Collision Avoidance System (TCAS) or Air Traffic Service (ATS) system and would unacceptably clutter screens if they were.
ADS-B signals will significantly load the 1090MHz aviation band, jeopardizing safety-critical TCAS and and Secondary Surveillance Radar (SSR) systems that depend upon it.
Use of the 1090MHz band for GA-GA/UAV is unjustified by the postulated but unquantified further reduction in mid-air conflict (MAC) risk and imposes disproportionate requirements and costs on GA devices, with the prospect of further or amended requirements as problems are discovered when operational.
The UK approach differs from the approach adopted in the EU. The UK-only approach is unlikely to attract significant commercial interest, resulting in few if any products and little subsequent development. And will hence prevent UK access to EU visitors unwilling to equip specially for the UK visit. The situation with UAVs and aircraft in proximity utilising different systems at the UK/EU border need to be considered, e.g. in N Ireland.
There are currently no installable devices that meet the proposed specification other than full Mode-S-ES; the single commercially available carry-on device has no provision for an external antenna and thus limited performance.
The small likely difference in price between any such devices and Mode-S-ES means that most pilots will equip with the latter, exacerbating spectrum congestion and degradation.
The practical lifetime of the proposed approach, bounded by the 2028/9 envisaged requirement date and current lack of installable devices, and the 2040 predicted 1090MHz frequency saturation, is unacceptably short.

CAA consultation question. Do the minimum performance requirements set out in CAP 3140 provide appropriate and workable technical requirements for the EC Mandate? Please explain your reasoning and provide any supporting evidence. If you think the scope should be drawn differently, please explain why and what alternative you would propose.

No. The proposal requires non-existent, internationally incompatible devices that use a safety-critical CAT band merely to address UAV integration with GA. This is risky, impractical and inappropriate, particularly when an internationally compatible, interoperable system using a different, regulated band already exists and can be installed today (ADS-L). There is little prospect of ground infrastructure, Commercial Air Transport (CAT) interoperability or Air Traffic Service (ATS) integration being achieved before predicted spectrum impact.

The grounds listed in CAP3140 Appendix C for rejection of ADS-L are specious:

RF power is not the problem – with proper, appropriately placed antennas, low power SRD 860 systems have proven ranges of tens of miles, vastly exceeding the short range required for collision avoidance (eg CAP3140 C39, C40) and useful situational awareness.
SRD 860 is a regulated frequency, so OFCOM should indeed ensure freedom from interference by non-compliant devices, which will rarely be close enough to have an effect. GNSS interference (CAP3140 C66, C67) is however a significant concern.
The ADS-L specification is not closed and proprietary (even the previously proprietary FLARM protocol is now public), and ADS-L devices are indeed air-to-air interoperable.
Without specialist technical competence to control the design and certification requirements for EC systemsthe CAA’s lack of control is entirely appropriate.
It doesn’t matter if other technologies use the same bands for other purposes, provided they conform to SRD 860 requirements.
In addition to the slide pack referred to in CAP3140 C29, NATS report ‘General Aviation: ADS-B/GPS Trial Results’ (2015) provides evidence that “the quality of non-certified GPS is sufficient for use in enhancing visual acquisition / electronic conspicuity of general aviation”
Quality indicator specifications should stem from performance and interoperability requirements. As CAP3140 C31 & C33 note, there is no prospect, before spectrum congestion becomes a problem, of interoperability with CAT ACAS or ATS; and the NATS study mentioned above makes clear that commercial off the shelf GPS is adequate for GA (and by extension UAV) use. No ACAS sXu products exist (C31), and it is unclear how widely they will be adopted. The CAA’s future aspirations (C35) depend upon infrastructure, hardware, systems and operational mechanisms that do not currently exist, are not planned, and have no funding to cover their very significant cost.

CAA consultation question. CAP 3140’s Position 6 sets out the ADS-B IN receive capability for crewed aircraft should remain a voluntary, operator-led choice rather than a mandatory requirement. Do you agree with this position? If no, please explain what approach you would propose and why, including the operational and safety implications. Please provide supporting evidence where available.

Yes.

CAA consultation question. Do you think there are circumstances in which the objective of an EC Mandate could be met through means other than direct carriage of EC equipment by the aircraft? If so, please explain how any alternative approach would deliver the objectives of the EC mandate set out in Chapter 3. Please provide evidence on the operational contexts where this might apply.

Yes. Where regular or planned activities occur in a well-defined area, such as parachute dropping, local flying / training, etc within a defined volume of airspace, the objective could be met through established airspace notification. Where intense activity occurs involving several aircraft on a temporary/short notice basis in a defined volume of airspace, the objective could be met through EC beacons.

CAA consultation question. The CAA and the Department for Transport are looking at how to balance clear rules with the flexibility needed as technology develops. This includes whether detailed technical requirements for EC equipment should be set out in guidance or other non-legislative documents, rather than in legislation. Is there anything you think we should take into account when considering this?

Yes. The CAA needs to do the required analysis before rushing into regulation. Once that analysis has been completed, the CAA needs to define the functional requirement and leave the technical aspects to those with the necessary competence.

CAA consultation question. Is there anything you would like us to consider as we develop our oversight and compliance approach to support effective implementation of an EC Mandate across different aircraft categories and operational contexts? Please provide examples where possible, including any aircraft categories where existing oversight mechanisms would not be appropriate or sufficient, and suggestions for how compliance might be assessed in those cases.

Yes. Compliance could be by ‘unwritten declaration by action’, i.e. if flying under the mandate, it should be assumed that the pilot in command has declared that they and the equipment are compliant, as they are with other regulations. It should be noted that similarly to hand-held radios and electronic flight-bags, carry-on EC is associated with a person or organization not an aircraft. General guidance to operators regarding serviceability checks may be useful.

CAA consultation question. Do you agree that a single compliance start date, following an adequate transition period, is preferable to a phased approach? If not, please explain what phased or alternative delivery model you would propose, which categories it should apply to, and why. Please provide supporting evidence.

No. There is a significant risk of unexpected/unintended consequences if introduced without pilot scheme, i.e:

Impact upon TCAS and SSR ability to detect CAT through spectrum loading
Impact upon airborne and ATS screens through screen clutter
Processes for dealing with intermittent functionality/loss of contact

CAA consultation question. Is the proposed transition period of approximately two years achievable across different operations? Please explain your reasoning and provide supporting evidence. Please include evidence on how quickly operators in your sector could realistically equip, whether sufficient EC equipment and installation capacity would be available, and what transition period would be more appropriate if two years is not sufficient.

Unlikely. Currently there are no installable 1090MHz ADS-B out devices that aren’t integrated into Mode-S transponders. Capacity for manufacture, installation, testing and in some cases installation approval does not currently exist for introduction at this scale.

CAA consultation question. Is there anything you want to tell us about the availability of compliant EC equipment and the capacity of the installation and maintenance sector to support implementation within the proposed timescales? Please provide specific evidence on equipment availability, installer capacity, lead times, and any other supply chain constraints relevant to your sector.

Yes. There is currently only one 1090MHz ADS-B-out device available that is not integrated into a Mode-S transponder – the uAvionix SkyEcho2. This is carry-on equipment. It has no provision for an external antenna and consequently performance can be poor.

A UK-only solution is unlikely to attract significant commercial investment in developing devices and associated displays and collision alert systems. f.u.n.k.e., which developed the Lower Power ADS-B Transponder (LPAT) for the CAA a decade ago, has notably not taken it to commercial production, and companies such as Garmin have been unwilling to enable the use of commercial off the shelf GPS sources that undercut their more expensive certified solutions. The only company likely to enter the market is the US firm uAvionix, which would enjoy a monopoly.

CAA consultation question. What costs would the proposed EC Mandate impose on you or the sector you represent? Please provide quantitative estimates where possible, including equipment purchase, installation, maintenance, training and any operational costs. If you consider that costs would fall on particular groups within your sector, please explain why and provide supporting evidence.

There are currently no installable devices available. Since a 1090MHz ADS-B transceiver differs from a Mode-S transponder only in software and the 1030MHz receiver (reckoned by one manufacturer to cost around £1 to include in the design), the cost is likely to be similar to that of a Mode-S-ES transponder, and indeed manufacturers may choose simply to modify their Mode-S-ES devices. The equipment cost is therefore likely to be around £2,500-3,000, plus antenna and cabling. Installation by a qualified engineer is likely to be £1,000-2,000.

In August 2026, the uavionix SkyEcho2 retailed at approximately £650 inc VAT. The cost will likely increase as market dynamics associated with any mandate evolve.

CAA consultation question. What evidence do you have on the likely operational impacts of the proposed EC Mandate? Please provide data, studies, or operational experience where available.

The mandated GA use of 1090MHz ADS-B could reduce the effectiveness of safety-critical Commercial Air Traffic systems TCAS and SSR, which must process but do not make use of GA ADS-B transmissions.

The impact upon the 1090MHz band was assessed in a CAA-commissioned study by QinetiQ, ‘Workstream 1: Analysis of the Capacity Limits of ADS-B on 1090MHz and 978MHz’ (2024), summarized as CAP3139 Chapter 3, which found that in the proposed mandated ‘from 2040, ever increasing congestion will be seen, and beyond the year 2040 continued 1090MHz loading may start to have an undesirable effect on SSR performance, especially in the absence of mitigating actions’. The report also stated that ‘there is a consensus of opinion that ADS-B on 1090MHz will (at some point) reach a saturation point. The precise ‘saturation point’ is not known as it depends on many factors’ and recommended that ‘The CAA should continue to take measures to carefully manage RF load on 1030/1090MHz.’

A previous simulation commissioned from QinetiQ by the CAA, ‘RF Environment Modelling for Widespread GA 1090MHz Conspicuity’ (2019), although vastly underestimating GA traffic densities, predicted the occurrence of automatic TCAS Interference Limiting, which result in ‘an inevitable reduction in the quality of TCAS surveillance. While there are specific provisions in TCAS to ensure that this does not compromise the conflict resolution capacity, the situational awareness provided by the TCAS traffic display will inevitably be less comprehensive.’

Should installable devices be similar in cost to full Mode-S-ES systems, and pilots choose to install these instead of ADS-B-only devices, the impact upon the 1090MHz spectrum will be substantially greater than in the QinetiQ model.

As currently developed, ADS-B will increase the hazards of distraction and complacency, while offering limited effectiveness especially in situations that present the principal collision risk.

QinetiQ’s CAA-commissioned ‘Workstream 5: Human Factors – integrating Electronic Conspicuity derived traffic into an existing ‘See and avoid’ airspace environment’ , summarized as CAP3139 Chapter 5, concluded that ‘The current key HF hazard is that (Electronic Conspicuity Devices) present a compelling and comprehensive traffic picture which may be incomplete or inaccurate if other ECDs cannot be detected increasing collision risk to the user’ and that while full EC interoperability might address this, ‘increasing the number of EC threats on … displays is likely to raise user workload. This may reduce user ability to detect traffic threats and increase strain on the user’s ability to conduct core flying tasks.’ The report noted the danger of distraction, as well as of control restriction and loose article hazards with carry-on devices.

The patchy detectability of some air-to-air EC systems is widely recognized, as reported in eg SESAR ‘GAINS D3.2 Airborne Validation Report’ (2019), ‘Airspace4All GA Airfield ATS ADS-B Traffic Display Trial’ (2019)

ADS-B is an RF data communications system which does not include information display, trajectory extrapolation, risk assessment, collision warning or avoidance advice, and proprietary front-ends generally implement only heads-down displays and simple proximity alerts with associated risks of distraction and complacency and loss of effectiveness. It fundamentally does not provide the additional information such as turn radius or flight mode that are used by advanced algorithms such as ONERA’s Patent US6438492B1 implemented under licence in FLARM devices. It is therefore likely to provide spurious alerts, leading to disregard or disconnection, in the situations of greatest collision risk.

SESAR’s ‘GAINS D4.4 Aerodrome Operations Demonstration Report’ (2019) noted that, when ADS-B data were used to provide collision awareness, ‘spurious warnings were generated in a busy visual circuit, which was particularly problematic when an ATC service was being provided. For example, at Dundee, pilots reported that they needed to concentrate their attention on flying the aircraft, visually searching for aircraft and listening to the ATC instructions.’ This is particularly unfortunate as, according to Helios’s CAA-commissioned ‘Review of existing Class G airspace risk studies’ (2014), ‘56% of powered aircraft collisions occurred over or near an airfield.’

CAA consultation question. Are there groups, sectors, aircraft types or regions that would be affected more than others by the proposed EC Mandate, either positively or negatively? Please explain and provide evidence where possible, including any equality, accessibility or unintended consequences. Please consider both the costs and the benefits when describing differential impacts.

Yes. Other than within GA business aviation and commercial activity, the cost and wider burden of complying with the proposed EC mandate would fall on a significant number of individual taxpayers. The primary beneficiary of the mandate as described is the UAV industry. This results in a significant negative impact for recreational GA and a significant benefit for the UAV industry.

CAA consultation question. Based on the evidence available to you, do you consider the CAA’s preferred approach would meet the safety and integration objectives set out in Chapter 3? Please explain your reasoning and provide supporting evidence. If you consider any aspects of the proposal would not meet those objectives, please identify which aspects and what changes you would propose.

No. In fact the consultation document does not define safety objectives or integration objectives. In the BGA’s view, the consultation’s UAV integration aim is the primary driver for the CAA’s EC mandate. As detailed above in our consultation question responses, the proposed mandate is a disproportionate and risky approach to the UAV integration aim and to one element within the layered approach to reducing mid-air conflict risk.

Thank you!

Thank you for taking the time to read this information. Please now go to the CAA’s online EC Mandate Consultation and submit your response to the CAA’s questions.

The CAA routinely identifies the number of responses to their consultations as indicative of the strength of feeling. Your comments CAN make a difference on a very important topic. Please do not leave it to someone else.