FLARM is a proprietary visibility system, widely used in gliding and in part of equipped free flight, while ADS-L is a more recent technology designed to be accessible to light aircraft, including paragliders.
Origin and adoption
FLARM was initially developed for gliders, with a trajectory prediction and proximity alert algorithm recognized in that field. It then spread to other free flight practices equipped with compatible instruments.
ADS-L is a more recent standard, designed to be integrated into compact and inexpensive units, with the goal of making electronic visibility accessible to as many pilots as possible.
Interoperability
FLARM and ADS-L rely on distinct protocols. A FLARM-only device does not natively receive an ADS-L signal, and vice versa. This is an important point to check before purchasing if you fly in an area frequented by FLARM-equipped gliders: some devices on the market advertise multi-protocol reception, others do not.
FLARM also calculates, on compatible devices, a trajectory and a proximity alert — a function that ADS-L does not natively integrate today. However, ADS-L messages contain the data necessary to build a function comparable, in its purpose, to that of FLARM: the OCAP project (Open Collision Avoidance Protocol), supported by the FOCA, has validated the technical feasibility of such a calculation based on ADS-L — without this certifying equivalence between products or guaranteeing that a given commercial device already implements it. Check on a case-by-case basis the functions confirmed by each manufacturer.
What to choose?
The choice depends on your practice and your usual flying area:
- Area frequented by FLARM-equipped gliders → check the FLARM compatibility of your future device.
- Mainly paragliding / free flight practice → the FOCA currently recommends ADS-L Out transmission, while keeping your existing FANET or FANET+ equipment during the transition (see our ADS-L guide for paragliding).
- When in doubt, a multi-protocol device broadens your mutual visibility, usually at a higher cost.
Our configurator takes your practice into account to guide your choice.