Do not make minimum airspeed assumptions, as we can trust our digital sensor a bit. A blocked pitot also most likely will result in more than just 6.5 m/s airspeed and so the check is based on a bunch of weak assumptions

src/modules/fw_att_control/fw_att_control_main.cpp

@@ -660,14 +660,13 @@ FixedwingAttitudeControl::task_main()
 
 				float airspeed;
 
-				/* if airspeed is smaller than min, the sensor is not giving good readings */
-				if ((_airspeed.indicated_airspeed_m_s < 0.5f * _parameters.airspeed_min) ||
-				    !isfinite(_airspeed.indicated_airspeed_m_s) ||
+				/* if airspeed is not updating, we assume the normal average speed */
+				if (!isfinite(_airspeed.true_airspeed_m_s) ||
 				    hrt_elapsed_time(&_airspeed.timestamp) > 1e6) {
 					airspeed = _parameters.airspeed_trim;
 
 				} else {
-					airspeed = _airspeed.indicated_airspeed_m_s;
+					airspeed = _airspeed.true_airspeed_m_s;
 				}
 
 				float airspeed_scaling = _parameters.airspeed_trim / airspeed;