Light general aviation aircraft

Disclaimer

The technology recommendation, while targeting the integration into the overall ecosystem, includes solutions meeting the requirements of the forthcoming mandate, as currently foreseen. These solutions can benefit from financial support under the Special Financing scheme (BV87b) as long as the mandate is not adopted. Aircraft owners and pilots who wish to benefit from this funding are encouraged to submit an application by November 30, 2026, at the latest. Please be aware that the mandate remains subject to change until its adoption.

This category includes light general aviation aircraft with a maximum take-off mass (MTOM) up to 2730 kg, up to 4 seats and a maximum cruising true airspeed up to 140 knots (KTAS).

Airspeed is directly affecting the ability to see and avoid. A combination of low antenna range and high closing speeds can lead to a very short time window for the pilots to react.

Therefore, the technology recommendation is split into aircraft with cruising speeds up to 140 knots TAS and aircraft with even higher cruising speeds.

The Mode S transponders without ADS-B are widely adopted and is the minimum equipment in a CTR, TMA or class E airspace at and above 7’000ft MSL, or class G when flying below VMC conditions (refer to VRV‑L Art. 29). In accordance with the forthcoming mandate, an existing Mode S transponder should be kept. When purchasing a new transponder, it is essential that it is capable of transmitting ADS-B Out.

Mode S transponders without ADS-B Out should be supplemented by one of the recommended technologies, because they are not always electronically visible (e.g. when there is no ground radar or TCAS interrogation).

Until the users equipped with ADS-L In devices represent a large majority, it is recommended to keep existing solutions (e.g. FLARM) and upgrade them to ADS-L. For example, existing FLARM installations can be upgraded to transmit ADS-L Out and there are ADS-L In/Out devices, which act as a “FLARM extender” to supplement an existing FLARM and which are connected to external antennas.

Technology recommendation:

1. Transponder with ADS-B Out installation in combination with ADS-L

Recommended due to the inherent benefits of a certified installation (e.g. known reliability, range, diversity). Ensures interoperability with traffic warning systems in other motor‑powered aircraft. This solution works well even at the highest aircraft speeds. The additional ADS-L In/Out device is needed to be visible to ADS-L In equipped users and to sense other traffic.

2. Traffic warning system in combination with ADS-B Out or ADS‑L

Recommended for traffic information, ideally with integration in certified avionics and the ability to receive traffic information via ADS-B, ADS-L and Mode S. A traffic warning system might only receive traffic and not transmit. Therefore, a combination with ADS-B Out or ADS-L is recommended.
Please note that such a system might not always detect other traffic with Mode S transponders. Mode S transponders without ADS-B will only transmit data when replying to Mode S interrogations from a ground radar or a TCAS.

3. ADS-L

ADS-L Out is a cost-effective alternative to be compliant with the forthcoming mandate while ADS-L In/Out is recommended for integration into the overall ecosystem. However the non‑certified nature brings limitations, such as varying degrees of system reliability, range or signal obstruction.            
External antennas are recommended to improve signal strength in all directions (diversity). Without external antennas, the airframe might block the device’s signal almost completely in some directions. Installation of external antennas is possible with a standard change (CS‑STAN).           
The signal obstruction issue could be reduced with multiple ground stations in range, which re‑broadcast emitted ADS-L signals. Diversity antennas are the best solution for air-to-air reception.