Hourly surface weather observations are combined with air traffic records to calculate the percentage interruption in airport runway operations due to fog that can be expected at 25 Air Force bases in the United States (17) and Europe (8). It is projected that approximately 1 to 2 percent of the flights in an average year can be expected to be affected by fog at bases in the United States. In Europe, the figures rise to 2 to 4 percent. During heavily fog plagued years, the projections can be expected to double. Persistence times are approximated. Empirical equations to allow calculation of percent mission interruption and duration of the interruption are presented that allow estimates to be made for bases other than the 25 selected for this investigation.

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An extensive investigation has been made to arrive at optimum specifications for a thermo-kinetic warm fog dispersal system. This study included passive heat tests, sub-scale heat/momentum tests, and tests with a single full-scale runway combustor and an approach zone combustor. These tests were augmented with extensive analytical modeling of buoyant jets under coflowing and counterflowing wind conditions. The landing category and the operational requirements within each category are the primary factors affecting the size of the thermal fog dispersal system (TFDS). A Cat 2 TFDS employs 22 percent fewer combustors and uses 50 percent less fuel than a Cat 1 TFDS. The combustor specification and orientation are presented for both Cat 1 and Cat 2 systems. (Author).