Wednesday, 25 January 2012
Evaluation of Convective Weather Avoidance Models for the Terminal Area
The effective management of convective weather in congested air space requires decision support tools that can translate weather information available to air traffic managers into anticipated impact on air traffic operations. For several years Lincoln Lab has been developing the Convective Weather Avoidance Model (CWAM) to correlate pilot behavior in the enroute airspace with observable weather parameters from convective weather forecast systems. The CWAM is used operationally to combine the echo tops and vertically integrated liquid (VIL) into the Weather Avoidance Field (WAF), a probabilistic forecast of the likelihood of weather avoidance. In recent years the WAF has become widely accepted as a reliable indicator of the impact of convective weather on air traffic operations. Adaptation of the CWAM into the terminal airspace with a focus on arrival decision making was presented at the Second Aviation, Range and Aerospace Meteorology Special Symposium on Weather-Air Traffic Management Integration in Seattle, WA in January of 2011. This study identified a number of weather avoidance decisions that could be used to classify the impact of weather on terminal operations. These include rerouting to an alternate corner post, holding in enroute airspace, or diverting to an alternate airport when weather is expected to impact the planned terminal trajectory. Initial results showed a strong correlation between the absolute echo top height and VIL on a dataset collected from the summer of 2009. This paper will focus on two areas of work for the terminal CWAM. First, an evaluation of the terminal CWAM developed for arrival decision making will be discussed. For this effort a test data set was created from weather impacts during the summer of 2010 and 2011 from several different terminal environments (i.e. a four corner post operation such as Chicago versus a complex terminal such as New York City). The discussion will begin with an analysis of the model calibration as well as an assessment of the model's ability to predict weather avoidance by looking at the probability of detection vs. false alarm rate. Next, the paper will analyze the effects of several different VIL and echo top spatial filters on model performance. Analysis of the model's ability to forecast weather avoidance based upon weather forecasts in the 0-2 hour time frame will be discussed as well as adaptation of the model to different terminal environments. Finally, the paper will present a comparison of three different convective weather avoidance models that have been developed for the terminal area - arrival, low altitude (level flight below 25kft) and departure (rapid ascent) phases of flight - and explore the possibility of consolidating the three terminal models.
This work was sponsored by the Federal Aviation Administration under Air Force Contract No. FA8721-05-C-0002. Opinions, interpretations, conclusions, and recommendations are those of the authors and are not necessarily endorsed by the United States Government.