An aircraft flight test program in natural icing conditions: part 2–correspondence between the forecast icing conditions, the actual icing conditions and the type and amount of ice accreted on the aircraft

“Part 1 – Forecasting for the Desired Meteorological Conditions” discussed the methodology used to forecast and direct aircraft into desired natural icing conditions. This paper uses case studies from the flight test program to illustrate the correspondence between the forecast icing conditions, actual icing conditions and the airframe ice that collected on the test aircraft during the icing flights. The test aircraft was instrumented with four high-quality video systems to record the accretion of ice on various parts of the airframe as well as readings from the aircraft instrument panel. The videos show how airframe ice accretes differently under different meteorological conditions. In addition, a data system recorded the status of an onboard ice detector plus aircraft and engine parameters required for drag calculations. Using these data, comparisons are made between meteorological conditions and the nature of the ice accreted on the aircraft.