One last time... FLARM does not need, nor does it record airspeed, for a simple reason: airspeed cannot be used to calculate closure rates between your aircraft and others, or ground obstructions. It works entirely from GPS fixes. It only uses a pressure sensor to enhance altitude data, but does not strictly need it. To my knowledge, no FLARM devices have inputs for airspeed.

Read the manual, folks. It's all documented there, in great detail.