13th Conference on Applied Climatology and the 10th Conference on Aviation, Range, and Aerospace Meteorology

Tuesday, 14 May 2002: 11:30 AM
Aircraft Encounters with Thunderstorms in Enroute vs. Terminal Airspace above Memphis, Tennessee
Dale A. Rhoda, MIT Lincoln Lab., Lexington, MA; and E. A. Kocab and M. L. Pawlak
Poster PDF (94.0 kB)
Recent studies have documented the surprising fact that commercial airline flights in terminal airspace frequently penetrate convective weather at low altitudes near destination airports. The study described in this paper examines the storm avoidance and penetration behavior of pilots in enroute airspace and compares it with the recent findings in terminal airspace.

Data were examined from six convection days over Memphis, TN, which serves as the intersection of several busy jetways. The aircraft encounters were split into two groups: those that occurred above 12,000 feet in airspace controlled by the Memphis Air Route Traffic Control Center (ZME) and those that occurred below 12,000 feet in airspace controlled by the Memphis TRACON. (The encounters in the TRACON airspace have already been described in an Y2K AMS paper. The two groups of planes encountered the same weather but they were flying at different altitudes and were in different stages of flight.

The avoidance behaviors in the two regimes are distinctly different. In the 43.5 hours examined, aircraft in the ZME airspace above the MEM TRACON appeared to penetrate convective weather 369 times as determined using a two-dimensional depiction of intensity. When examined in a 3-dimensional analysis, however, using pencil-beam radar data, it becomes clear that the ZME aircraft only penetrated 4 times -- 365 of the apparent penetrations were actually flying above the radar reflectivity. The ZME planes deviated around the weather 205 times. The aircraft in the terminal airspace deviated 439 times and penetrated (in a 3-dimensional sense) 381 times in the same time period as the higher-altitude analysis.

The paper describes the methodology used in the study, discusses some of the operationally relevant differences between the flight regimes, and discusses options for future automation to help air traffic managers identify airspace where pilots will fly and airspace that pilots will avoid.

* This work was sponsored by the Federal Aviation Administration under Air Force Contract No. F19628-00-C-0002. The views expressed are those of the authors and do not reflect the official policy or position of the U.S. Government. Opinions, interpretations, conclusions, and recommendations are those of the authors and are not necessarily endorsed by the US Government.

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