1. Mulally, A.R., M.D. Shirkey, and C.R. Higgins, 1989: Winter operations-keep it clean. BOeing AIRLINER. ' Federal Aviation Administration, 1990: Federal Aviation Regulations and Airman's Information Manual. FAR 91-52,53 and Figure 5-15, Para 433.
2. ' Federal Aviation Administration, 1975: Aviation weather, 92-93.