Chicago Monostatic Acoustic Vortex Sensing System. Volume IV. Wake Vortex Decay.

A Monostatic Acoustic Vortex Sensing System (MAVSS) was installed at Chicago's O'Hare International Airport to measure the strength and decay of aircraft wake vortices from landing aircraft. The MAVSS consists of an array of acoustic antennas which measure the vertical profile up to 60-m altitude of the vertical component of the wind. The decay in wake vortex strength is measured as the vortex passes over successive antennas in the array. Volume I (published in October 1979, 32 pages) described the MAVSS principles of operation, the hardware developed, and the data reduction methods employed. Volume II (published in September 1981, 162 pages) described the analysis of MAVSS data to examine whether landing B-707 and DC-8 aircraft need to remain divided into Heavy and Large categories on the basis of the wake vortex hazard. Volume III (published in January 1982, 25 pages) summarized the results of Volume II in terms of the saftey implications of categorizing all landing B-707s and DC-8s as Large aircraft. In this volume, the statistical methods used to understand wake vortex decay are described and the data on all common jet transport aircraft are presented. (Author)