On Thursday, February 18, 2021 at 6:59:58 PM UTC-8, Mike Schumann wrote:
On Thursday, February 18, 2021 at 6:04:47 PM UTC-6, Jeff Bures wrote:
I gather that FLARM is much more popular outside of the USA. Are most well equipped sailplanes installing FLARM in the USA? What about other GA aircraft in the USA?

Is FLARM more common (or a necessity) at competitions in the USA? For club and casual cross-country soaring, it might be less prominent.

Having both FLARM in/out and ADS-B in/out is getting quite expensive. Would a budget minded sailplane in the USA get FLARM or ADS-B. Which has the most utility for situational awareness and safety in the USA?

What does FLARM offer that ADS-B does not? I'm assuming FLARM is faster and more accurate for gaggles. What's the relative refresh for FLARM and ADS-B data?

Yes, I know ADS-B out would open up some airspace that would normally be excluded, but I'm ignoring that factor for now.
There are virtually no GA aircraft in the US equipped with FLARM. Both FLARM and ADS-B have a refresh rate of 1 second. The accuracy of the position transmissions for both FLARM and ADS-B are virtually identical, as both are limited by the accuracy of GPS signals received by the aircraft.

The difference between the two systems is primarily in the collision avoidance algorithms implemented by the systems. FLARM is focused on dealing with gliders which can fly in relatively close quarters. ADS-B receivers themselves do not generally incorporate collision avoidance algorithms. Instead they just pass along traffic information to whichever display devices they connect to. Various display devices and/or apps have collision warning algorithms of varying sophistication. While most ADS-B systems are focused on providing situational awareness to pilots so they can see and be warned of other traffic in their vicinity, the goal is usually to give other aircraft a relatively wide birth, not to coordinating flying at close quarters.

Technically, there is nothing preventing the development of an ADS-B receiver with as sophisticated a collision avoidance algorithm as FLARM, but given the relatively small size of the glider market in the US, it does not appear that there is any significant effort to develop that kind of system.

Thanks for the great info. It helped!