Results of Initial Feasibility Study on Tactical Support Information for Avoiding Aircraft Lightning Strikes

Aircraft lightning strike is one of issues which users strongly demand to solve. An aircraft lightning strike does not directly cause a fatal accident because aircraft are designed, manufactured, and certified to be sufficiently tolerant to lightning strikes. Once it happens, however, aircraft have to be fully inspected. When damages are detected, aircraft have to be take first aid repairs or factory repairs. The inspections and first aid repairs frequently result in delays of following flights, and the factory repairs have the aircraft stop servicing and cancel following flights. In Japan, it is estimated that hundreds of aircraft lightning strikes happen and they yearly cost millions of dollars at least.

Japan aerospace exploration agency and collaborators have conducted the initial feasibility study to develop tactical support information for avoiding aircraft lightning strikes [1]. In the initial feasibility study, weather and flight data were collected with respect to actual cases of aircraft lightning strikes which happened in winter seasons of 2015—2016 and 2016—2017 in Shonai area (in coastal area of the Japan sea) where it is known that winter lightning happens. The weather data were obtained by C-band weather radars and radiosondes (data provided by Japan Meteorological Agency), and flight data were provided by All Nippon Airways Co., Ltd. (ANA). Analyses of the weather and flight data indicated common trends in the actual cases, and derived safety thresholds on vertical integrated reflectivity and -10-degC-height reflectivity. The thresholds were evaluated by the fourteen actual cases and seventy-six cases with no aircraft lightning strike, and the evaluation showed that 60—80% of current aircraft lightning strikes can be avoided. (An example of the tactical support information is shown in Figure 1.)

Beyond explanations of the initial feasibility study, the presentation introduces future possible updates, which includes various technologies such as a phased array weather radar with evolutionally fast scanning capability of 10—30 sec refresh rate [2], upper-altitude atmospheric data downlinked by Second Surveillance Radar (SSR) mode S [3], a network of distributed electric field mills that enables early detection of charging clouds [4], and AI technology to improve probability of detection or false alarm rate of the tactical support information [5].

Fig. 1: An Example of Aircraft Lightning Avoidance Information.
Red circles: risk areas; contour: 2-km-altitude radar echo; red triangle: airplane.

Acknowledgment: This presentation is partly based on results obtained from a project commissioned by the New Energy and Industrial Technology Development Organization (NEDO).

[1] E. Yoshikawa, S. Yoshida, T. Adachi, H. Inoue, K. Kusunoki, Y. Takahashi, S. Shimamura, and T. Ushio, “Progress on Feasibility Study of Airport Lightning Avoidance System,” 18th Conference on Aviation, Range, and Aerospace Meteorology, AMS annual meeting 2017, Seattle.

[2] F. Mizutani, T. Ushio, E. Yoshikawa, S. Shimamura, H Kikuchi, M. Wada, S. Satoh, and T. Iguchi, 2018: Fast-Scanning Phased-Array Weather Radar with Angular Imaging Technique, IEEE Trans. Geosci. Remote Sens., vol. 56(5), pp. 2664—2673.

[3] A. Senoguchi, “DAPs Potential and an Analysis on Weather Uncertainty for TBO,” ICAO/WMO APAC MET/ATM Seminar 2015, SP/12, 2015.

[4] T. Kudo, and M. Kamogawa, “Lightning early warning systems based on ground-based field mill network”, Proc. 16th Int. Conf. Atmos. Electricity, 2018, Nara.

[5] S. Okada, M. Kono, T. Nishi, K. Suzuki, T. Ogisu, and I. Murata, “Development of Next Generation Aircraft Operation Support System,” SUBARU Technical review, no. 45, 2018, pp. 206—209 (in Japanese).