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airspeed scenarios. Each scenario requires the pilot to hold airspeed, vertical speed, pitch, and roll precisely for up to 2.5 minutes. Exceeding any one of the tolerances invalidates the calibration. For example, the speed target is +/ – 3 mph, and the pitch cannot vary by more than one degree. (Most autopilots cannot achieve this level of precision.) I found the calibration process to be challenging, especially during the final step when the airplane has the flaps and gear extended. On our particular day, the airplane was loaded with CG forward, so hand-flying and holding a target speed just above stall, while complying with the tolerances, demanded concentration and strength. Performing the calibration on a calm day is a must.Following calibration, the Aspen Avionics AOA manual instructs the pilot to configure the airplane for landing, flaps and gear down, and perform a power-off stall to test the system. As the airplane slows, the pilot observes a graphic on the EVO 1000 PFD (or EVO 2000 MFD). Two pointers travel vertically along a set of stacked colored bands that represent the CL range. The lower pointer indicates the CL when the airplane is dirty, the upper when it is clean. Starting at the bottom, the bands are colored blue (representing high remaining lift capacity), green, and then yellow. At the top, yellow with black hash marks represents low remaining lift capacity. As the airplane slows both pointers move upward, butwith the airplane configured dirty, only the lower point indicates CL and proximity to a stall. It is this pointer that the pilot follows.The second test is conducted with the airplane clean, this time keeping an eye on the upper pointer to determine CL. I queried Michael Studley, Aspen’s Director, Customer Service – Field Service Engineering, about the need for two pointers (confusing). He acknowledged that the two-pointer representation requires some practice, but affirmed that it is more accurate than competitor products that use one pointer and blend multiple configurations for their CL calculation. Also, according to Studley, the configuration that amphibians use to land on sea – wheels up, flaps down – changes the CL calculation minimally compared to land ops, so happily a third pointer is not necessary.Using The SystemThe post-calibration tests ultimately proved that the system was working. Power-off stalls in the Widgeon while dirty are very honest. Applying a normal recovery, pitch down/full power, flaps to approach, positive rate, gear-up, can be accomplished with fewer than 200 feet of altitude. Even more impressive is the performance of Aspen’s branded AOA. Just prior to the stall, the lower pointer was near the top of the yellow hashed band, exactly where it should be. The same excellent performance was observedASE, Inc. Half Page 4/C Ad12 • TWIN & TURBINEJANUARY 2016