Distribution of aviation weather hazard information: Low Altitude Wind Shear

This paper addresses, in general, the challenge of producing and distributing timely, accurate and pertinent information regarding weather obstacles to commercial aviation. It specifically focuses on the production and distribution of low altitude wind shear information to aviation’s operational safety decision makers, the air traffic controller, flight dispatcher and pilot. Methods used to differentiate between inaccurate and non pertinent wind shear alerts and those shears generated by weather severe enough to significantly impact the performance of commercial aircraft are described.

Current manual and automated methods used to produce low altitude windshear alerts are described. They are addressed in the context of the meteorological processes generating the shears. Past work done to conceptually define the process that produces these shears as well as commercial airline accidents where low altitude wind shear was a probable cause is briefly reviewed.

The FAA’s program to produce low altitude windshear alerts called TWIP (Terminal Weather Information for Pilots) is described. The pro’s and con’s of two distribution methods (“push” and “pull’) are described.

Results of analysis of the accuracy of TWIP data over a two year period, 1998-2000 is presented. Specific focus is on alerts generated when “NO STORMS WITHIN 15NM” were detected. Based on analysis of the meteorological conditions at the time of the alerts, it is concluded that a large percentage of these alerts were inaccurate and unwarranted. A summary is provided of actions completed, planned and proposed to eliminate the distribution of alerts which do not have a significant impact on the operational performance of commercial aircraft.