Abstract

The presence of wake vortices on airport runways has been a potential hazard for aircraft during takeoff and landing since the introduction of wide-bodied passenger transport aircraft, such as the B 747 and the DC10, in the early nineteen seventies. The problem was quickly recognised by the US Federal Aviation Administration (FAA) and studies were initiated into methods of detecting and tracking the vortices (1) and also into ways of reducing their strength, although the latter only achieved limited success. In particular, a number of studies performed during the mid-nineteen seventies (2) showed that vortices could be detected and tracked using coherent laser systems operating at a wavelength of 10 micrometres by measuring the large Doppler frequency shifts produced at the extremities of the vortex. Extensive measurements were made at J F Kennedy International Airport using a CW system which scanned a focussed beam in a plane transverse to the runway and this system enabled measurements to be made of the vortices produced by a large number of differing aircraft types. Subsequently, operating procedures were introduced, based upon these findings, which provided adequate protection for following aircraft by adjusting the separation distance between landings depending upon the weight classifications of the leading and following aircraft. Little funding has been available since that time to study the wake vortex problem further and the subject has been largely dormant for the past 10 years although Koepp (3) reported some measurements in 1985.

© 1991 Optical Society of America