A preliminary study to investigate lightning strikes to helicopters operating over the North Sea showed that on a significant number of the events the pilots reported no previous lightning activity to be present. This led to the hypothesis that the helicopter triggered the lightning strike as a result of its presence at that point in space and time. Fourteen incidents dating back to 1992 have been studied. The analysis of the synoptic data (synoptic charts and satellite pictures) showed that in all cases being studied, cumulonimbus (Cb) clouds were in the vicinity. This information is not strictly in contradiction to the previous study in that the Cbs may not have started producing lightning until the helicopter flew into it.
A null data set was generated from dates, times and locations when similar Cb clouds were present alongside helicopters and a lightning strike did not occur. The Met. Office NWP model data from both strike and null data sets were used in a statistical regression analysis. The resulting statistical model equation uses temperature and vertical velocity as key predictors of a lightning strike to helicopters operating in this region such that the probability of the results being random were less that 1 in 100
The 8th Conference on Aviation, Range, and Aerospace Meteorology