FLARM

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FLARM is an electronic device to selectively alert pilots to potential collisions between aircraft. It applies the ADS-B concept to recreational aviation.

FLARM (the name being inspired from 'flight alarm') obtains its position from an integral GPS and a barometric sensor and then broadcasts this with forecasted data about the future 3d flight track. Its receiver listens for other FLARM devices within typically 3-5 kilometres and processes the information received. Motion-prediction algorithms predict potential conflicts for up to 50 other signals and warn the pilot using sound and visual means. FLARM can also store information about static aerial obstacles, such as cables, in a database. The FLARM serial data protocol is public, while the FLARM radio-protocol is proprietary and licensed to manufacturers; both protocols are copyright-protected.

Unlike conventional transponders in aircraft, FLARM has a low power consumption and is relatively cheap to buy (570 euro plus tax) and to install. Furthermore conventional Airborne Collision Avoidance Systems (ACAS) are little use in preventing gliders from colliding with each other because these aircraft are frequently close to each other without being in danger of collision. ACAS would be giving out continuous and unnecessary warnings in these circumstances, whereas FLARM only gives selective alerts to aircraft posing a collision risk. However the short range of the present power output makes FLARM unsuitable for avoiding collisions with fast moving aircraft.

FLARM was founded by Urs Rothacher and Andrea Schlapbach in 2003, joined by Urban Mäder in 2004. First sales were made in early 2004. Currently there are over 10,000 FLARM-compatible units (over 8'000 produced by FLARM Technology, over 2'500 by licensed 3rd party manufacturers who have now overtaken FLARM in current sales) in use mainly in Switzerland, Germany, France, Austria, Italy, the Benelux, Scandinavia, Hungary, Israel, Australia, New Zealand and South Africa. Since early 2007 it is being adopted in the UK after the telecom authority and Civil Aviation Authority confirmed that it was acceptable.