11.5 Lee waves associated with a commercial jetliner accident at Denver International Airport

Wednesday, 20 August 2014: 4:30 PM
Kon Tiki Ballroom (Catamaran Resort Hotel)
T. L. Keller, NCAR, Boulder, CO; and S. B. Trier, W. D. Hall, R. D. Sharman, M. Xu, and S. Liu

On 20 December 2008 a Boeing 737 aircraft encountered a significant crosswind gust during takeoff roll, causing it to veer off the runway at Denver International Airport (DIA). All passengers were able to escape before the plane burst into flames.

Data from wind sensors at DIA showed winds were predominantly from the west, with an area of high wind speeds and gustiness near the center of the airport around the time of the accident. According to the report from the National Transportation and Safety Board one of these strong gusts initiated the events leading to the runway excursion and subsequent crash. In addition, numerous aircraft reported moderate to severe turbulence, as well as significant mountain wave activity, over Colorado for several hours before and after the accident.

To identify the meteorological conditions contributing to the strong, intermittent gustiness at DIA, a high resolution simulation using the Clark-Hall nonhydrostatic numerical model, with a horizontal grid spacing of 250 m in the inner domain, was performed. Results from this simulation showed significant wave activity over both the Rocky Mountains and the eastern Colorado plains near the time of the accident. A train of lee waves amplifying in a mid-tropospheric stable layer above the airport created regions of higher velocity air eroding to the surface, resulting in surface gustiness at DIA. Another simulation using the WRF model with a 3 km horizontal resolution, similar to the state-of-the art HRRR operational model, shows current operational models have insufficient resolution to capture this event. These model results and meteorological conditions will be discussed.

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