Radiometrics Corporation (formerly Atmospheric Systems Corporation)

Sonic detection and ranging technology solution for airports industry - Aerospace & Air Transport

SoDAR provides critical information on several fronts for airports as well. This information is both weather related and plane related. Since lives are at risk, timeliness of information is of the utmost importance.

A type of weather phenomenon called 'microbursts' can produce extremely strong wind shear, posing great danger to aircraft. These are local, short-lived downdrafts that radiate outward as they rush toward the ground. As a downdraft spreads down and outward from a cloud, it creates an increasing headwind over the wings of an oncoming aircraft. This headwind causes a sudden leap in airspeed, and the plane lifts. If the pilots are unaware that this speed increase is caused by wind shear, they are likely to react by reducing engine power. However, as the plane passes through the shear, the wind quickly becomes a downdraft and then a tailwind. This reduces the speed of air over the wings, and the extra lift and speed vanish. Because the plane is now flying on reduced power, it is vulnerable to sudden loss of airspeed and altitude. The pilots may be able to escape the microburst by adding power to the engines. But if the shear is strong enough, they may be forced to crash land. Hundreds of fatalities and injuries have result from this phenomena. 

Another event that can be detected using SODAR technology is the wake vortex that is produced by aircraft during landing. The persistence of some of these wakes along the landing runway has resulted in the loss of aircraft following behind other aircraft. Most often the situation is associated with a smaller aircraft following a larger aircraft (such as a 747 or equivalent). 

During the past 10 years Doppler SODAR has demonstrated its ability to detect the strong upward and downward motion that is characteristic of these vortices. The detection of the presence of the wake vortex as well as being able to monitor the duration of the wake vortex is a critical feature for a monitoring system. This reduces the risk of accidents and can make airport throughput more efficient.

Alternative designs of the SODAR are also capable of real time monitoring of the ability of the atmosphere to sustain these vortices. It is well known that there are certain atmospheric conditions during which these wake vortices persist and other conditions during which they decay rapidly or are transported away from the runway.