Confessions of a Flarm Follower

1) FLARM has a proprietary algorithm that determines which nearby gliders will trigger an alarm. In an ADS-B world, don't we still need that? Don't we need a glider specific ADB-S set up? If so can't the competition mode be transferred to ADS-B?

2) Looks like building a cheap ADS-B specific for sailplane racing should be a breeze. At $120 there should be few complaints about adoption.


Easier said than done to mash Flarm collision algorithms onto ADS-B position reporting. The two systems have some fundamental architectural difference - previously discussed here - that make it hard to use ADS-B to both do good collision warning and not go totally nuts in thermals and other close proximity flying.

You could certainly in theory write software for a home brew ADS-B In receiver that did whatever you like in terms of filtering traffic. I think the challenge will be getting agreement to require pilots to carry that device and only that device for receiving ADS-B. You also get into the cost and complexities of supporting the code and the customers and....wait for it...product liability if it has a problem.

The other problem is Flarm will use ICAO addresses to de-duplicate targets carrying both ADS-B and Flarm, reverting to the more sophisticated Flarm algorithm and transmission when it has a good Flarm signal. Trying to do that across two separate devices would be very complicated.

The reason you'd want it would be to layer in UAT and ADS-R traffic that Flarm doesn't pick up...and in the process to circumvent stealth, I suppose.

9B