Glider pilot reported a complex firmware update is required for the FLARM TCAS unit to provide traffic avoidance and advisories. The reporter stated no advance notice of the update is provided by the company.

Narrative

I was flying my glider in mountain wave conditions within controlled airspace under a clearance. Another glider was also flying in the same area with the same clearance. We both had a TCAS system used in gliders called FLARM. The FLARM company requires a yearly firmware update which renders the system nonfunctional if the update is not made. The update is very complex and could not be done by either pilot prior to flight. So the FLARM units were nonfunctional on our big screen PFD's. Fortunately we both carried Stratus 2 ADSB-in devices connected to iPhones running Foreflight which give traffic information and alerts. I was monitoring my iPhone and watching the other glider approach and saw that we were going to miss each other by the above reported distances. Those distances are exact due to comparison between the two GPS tracklogs.The fact that a firmware update is required to continue the operation of a traffic alert system is wrong and dangerous. The traffic alert system should continue to function even without the update since there is no prior warning of an update requirement sent to the pilot and if discovered on the day of flight is unlikely to be performed successfully. I have emailed the FLARM company about this problem and await their reply. If NASA also contacted FLARM there would be more weight behind the conversation; and a correction by the FLARM company would be more assured.