Gliders

Gliders need to be electronically visible to motor-powered aircraft. This can be achieved with either ADS-L or ADS-B. The FOCA recommends to keep an existing Mode S transponder and if possible, upgrade to ADS-B Out.

There are thousands of FLARM installations in gliders. This is a great solution for collision awareness among gliders.

Technology recommendation:

1. FLARM in connection with ADS-L In/Out or with ADS-B Out

FLARM is ideal for use among gliders. To improve interoperability with motor-powered aircraft, the FOCA recommends using a FLARM device with the ability to receive ADS-B and Mode S signals. For best interoperability, the device should be combined with either ADS‑B Out or ADS-L In/Out.     
If ADS-L In/Out is used as a standalone device without FLARM, there may be disadvantages for collision awareness with other gliders (e.g. in thermals). This is because the collision awareness protocols in apps like ForeFlight, SkyDemon etc. are not built for gliders.

ADS-B Out is recommended due to the inherent benefits of a permanent installation (e.g. known reliability, range, diversity). It ensures interoperability with traffic warning systems in motor‑-powered aircraft.