An aircraft flight test program in natural icing conditions: part 1—forecasting for the desired meteorological conditions

An aircraft flight test program was conducted recently in natural icing conditions to test new aircraft deicing boot operational procedures. Locating icing with a minimum amount of flight time is critical to the success of such a program since flight test is extremely costly in terms of the equipment and personnel required to properly execute such operations. Further, the tests often require a certain type, or types, of icing to meet the demands of the test or certification flights. Based on extensive flight experience and scientific research, the authors have developed methodology to forecast and direct aircraft into specific types of icing conditions. An understanding of the meteorological conditions which produce icing and the type of icing to be expected in each condition is essential. The technique uses information readily available on the Internet and telephone communications with the aircraft to direct them into the icing conditions in real-time. Both maximum intermittent and maximum continuous conditions were successfully located and penetrated using these techniques, while the total flight-test hours were minimized. The flight test program consisted of 13 days with 36 icing encounters. The program was completed ahead of schedule with all goals being realized. This paper discusses the specific techniques used to forecast the desired icing conditions and to direct the flights into those conditions.