The pressure differential is thus smaller, and the needle responds accordingly falling to the left on the dial . As angle of attack increases and airspeed decreases, the pressure differential continues to fall, until the probe points directly into the wind and both faces strike the air at a 45-degree angle. At this point the pressure differential is zero. The green band indicates a very large lift reserve and that airspeed is too high for proper landing. Every LRI installation must be individually calibrated.
Calibration normally takes three or four landings, each followed by minute probe adjustments.
Installation, in most cases is no big deal. In the case of the Aviation Consumer Mooney, the probe was installed on one of the inspection plates on the bottom of the wing. The two air tubes were strung along the wing to the cockpit instrument. LRI's are installed as minor modifications according to FAA Form 337, which requires the signature of an A1 rated mechanic. Since the LRI does not tie into any other aircraft system, this seems reasonable.