Is ADS-L a collision-avoidance system?

No, there is no guarantee that it allows collisions to be avoided. However, it may contribute to an alert function depending on the implementation: its messages contain the necessary data (position, altitude, speed) to build a function comparable to that of FLARM, feasibility validated by the OCAP project, supported by FOCA. This does not say whether a commercial product already implements it — check case by case the functions actually announced by each manufacturer.

Does ADS-L work with FLARM or ADS-B?

These are distinct technologies that do not natively communicate with each other. See our overview of electronic conspicuity technologies and our ADS-L vs FLARM and ADS-L vs ADS-B comparisons for details.

Do I need a radio license to use an ADS-L device?

This depends on the regulations in force and the type of device. Check the manufacturer's official documentation and the ADS-L in Switzerland page for the applicable framework.

What is the difference between Issue 1, Issue 2 and Issue 3 of ADS-L?

These are successive editions of the EASA technical specification for ADS-L on the SRD860 band. Issue 1 defined the basic protocol; Issue 2, published on December 1, 2025, adds ground-to-air retransmission and improved interoperability between devices; Issue 3 is a future evolution, not yet finalized.

What is ADS-L?

ADS-L (Automatic Dependent Surveillance – Light) is a lightweight electronic conspicuity technology: an equipped device periodically transmits its position (GPS), altitude and speed by radio, so that other aircraft equipped with compatible receivers can perceive it on their screen or instrument.

Why "light"?

Unlike ADS-B, used by commercial and general aviation, ADS-L was designed for light aircraft that are inexpensive to equip — including paragliders, hang gliders and gliders — with compact equipment, reduced power consumption and a modest acquisition cost.

What ADS-L does

Transmit the position of an equipped aircraft (transmission).
Receive and display the position of other equipped aircraft (reception).
Improve mutual conspicuity between aircraft in shared airspace.

What ADS-L does not do

ADS-L is not a collision-avoidance guarantee. An ADS-L device does not detect unequipped aircraft, does not slow down or divert anyone, and does not exempt anyone from maintaining constant visual lookout. It is an additional perception tool, not a substitute for caution.

That said, ADS-L messages contain the elements (position, altitude, speed) needed to build a collision-avoidance function comparable, in purpose, to that of FLARM — different protocols, comparable content. The OCAP project (Open Collision Avoidance Protocol), supported by FOCA, has validated the technical feasibility of such a functionality based on ADS-L. This does not certify equivalence with FLARM, nor does it guarantee that a given commercial product already implements it: check each device's product page for its actually confirmed functions.

Who is concerned?

Eventually, electronic conspicuity potentially concerns several categories of aircraft sharing the same airspace: paragliders, hang gliders, gliders, ULMs and light aviation. The exact timeline and scope depend on national regulations — see our ADS-L in Switzerland page for the up-to-date status.

Editions of the specification: Issue 1, Issue 2, Issue 3

The ADS-L technical specification (SRD860 band) published by EASA evolves through numbered editions, called "Issue":

Issue 1: first edition, which defined the basic protocol — direct transmission/reception between devices on non-certified equipment.
Issue 2: published by EASA on December 1, 2025, following feedback on Issue 1. It brings clarifications on transmission requirements, a new ground-to-air retransmission capability (traffic information and aeronautical data) and improved interoperability through the broadcast of each device's capabilities.
Issue 3: future evolution of the specification, not yet finalized. Some manufacturers mention a direct migration to this edition rather than Issue 2, notably with a view to future support for drone RemoteID on the same radio system.

FOCA refers to Issue 2: its official FAQ on the FASST-CH plan directly refers to the EASA publication "ADS-L 4 SRD860 Issue 2" as the technical reference for the ADS-L system. This simple link does not establish an obligation of compliance with a specific edition, nor a certification of future compliance for devices already sold: it merely indicates that Issue 2 is the edition currently cited by the Swiss regulator. The edition actually implemented by a manufacturer on a given device, and any announced migration to a later edition, are two distinct pieces of information — see each product's page.

In summary

ADS-L allows a light aircraft to be seen electronically by other equipped aircraft. It is an additional safety building block, not an automatic separation system.

Sources

The technical and regulatory information on this page reflects publications by EASA and FOCA as of the last verification date (25.09.2026). Specifications and the regulatory timeline may change: always check the official sources above for the version in force.