Lasers probe clear air for turbulence

Research could help pilots ‘see and avoid’ bumps

August 13, 2013

A probe attached to a Cessna Citation emits ultraviolet laser light. The backscatter reveals disturbances in clear air. Photo courtesy DLR

Advanced warning, or even avoidance of clear-air turbulence may be possible in coming years, and a Cessna Citation is flying circuits out of Amsterdam and over Europe to make it happen.

The joint effort by various European aerospace agencies seeks to detect wind shear strong enough to produce waves which compromise smooth airflow over wings, and lift. Those waves are the cause of clear-air turbulence.

Computers analyze the laser data to detect turbulence.  Photo courtesy DLR

A short-wave, ultraviolet laser mounted on a probe extending forward of the Citation’s nose sends a beam along the flight path, and sensitive instruments measure the backscatter, or reflection, of that light from air molecules. The density of oxygen and nitrogen can then be calculated, and clear air turbulence is then revealed indirectly.

Researchers from several countries are collaborating in hope that one day a cockpit instrument could give pilots enough warning to direct passengers to their seats, or, better still, steer around the bumps.