Observations of aircraft proximity to weather for use in rerouting decision aids

Abstract

Information about pilot behavior in the presence of weather is needed if a decision aid is to be created to assist with enroute replanning. Specifically it is important to know how close pilots are willing to fly to various levels of precipitation. Two surveys and an analytical study were conducted in order to examine pilot preferences and behavior in enroute replanning decision making. The first survey involved a questionnaire on the world wide web and the second survey consisted of a more focused series of personal interviews. Replanning decisions in response to turbulence and weather were examined. Weather was determined to be the largest cause of pilot initiated inflight replanning, and pilot reports appeared to be an influential information source in light weather. In moderate or severe weather the effects of pilot reports were decreased. Next, an analytical study was performed in which enroute flight track data archived from the Dallas Fort- Worth area was correlated with precipitation intensity data to assess pilot behavior in the presence of weather. Twelve hours of data during a cold-front passage were examined to generate statistics on pilot proximity to weather of varying intensity levels. This data also included the duration of the penetrations and the closest point of approach to each level of precipitation. The duration in more severe levels of weather was smaller than predicted by a simplified model of the weather. Also, the correlation between lead and following aircraft duration and proximity to weather was examined. A slight but insignificant trend for the following aircraft to spend less time in weather than the leading aircraft was discovered. However, it appears that the severity of the weather in the twelve hour period of interest was sufficiently severe to lessen the effects of the lead aircraft.