For most air travelers, turbulence provides nothing more serious than the odd moment of extreme panic, but it costs airlines hundreds of millions of dollars each year in injury compensation and aircraft damage. There are various different types of turbulence, but the most dangerous, because it is invisible and extremely difficult to detect, is clear-air turbulence (CAT). A new CAT detection technology that could help pilots choose a smoother route is now being tested as part of a European joint project called DELICAT (Demonstration of LIDAR based CAT detection).
As its name suggests, CAT can occur when no clouds are visible, providing no visual cues of its presence. Occurring most often at altitudes of around 7,000 to 12,000 m (23,000 to 39,000 ft), CAT is caused when bodies of air moving at different speeds collide with each other. Researchers at the German Aerospace Center (DLR) say that recent atmospheric studies indicate that CAT will become an even bigger problem in the future as climate change is expected to increase the frequency of CAT.
To minimize the dangers of CAT, DLR and its DELICAT project partners are testing a laser-based measurement device on flights throughout Europe. The LIDAR (Light Detection and Ranging) instrument, which was developed by researchers at the DLR Institute of Atmospheric Physics, emits short-wave ultraviolet laser radiation in the direction of the flight. By measuring the reflected signal from oxygen and nitrogen molecules, the device can detect fluctuations in air density and provide a warning of CAT in advance.
The system has been installed on a modified Cessna Citation aircraft that will be used in a flight campaign throughout Europe until the end of August. At the end of the test flights, the measurement data will be analyzed. The data will not only be used to demonstrate the system’s efficacy, but will also provide the researchers with information on the conditions in which CAT is likely to form.
The research team hopes their work will lead to the development of a detection system that could be integrated into aircraft so that pilots would have advance warning of CAT, giving them the potential to fly around the turbulence or, failing that, time to ask passengers to buckle up.