Avoiding the Rough Spots

Although today’s commercial aircraft are more than tough enough to withstand being bounced about by air pockets, sometimes passengers aren’t: Turbulence in otherwise calm stretches of air is the leading cause of in-flight injuries. Seeing turbulence ahead of time could save airlines millions of dollars a year, by averting in-flight injuries and also by saving fuel wasted in churning through bumpy air. The National Aeronautics and Space Administration (NASA) is testing a sensor device that could do just that.

The device, designed and built for NASA by Coherent Technologies of Lafayette, Colo., uses LiDAR technology. LiDAR is the optical analog of radar: Instead of radio waves, pulses of infrared light are transmitted, some of which bounce off particles and back to a sensor. NASA’s sensor detects the changing velocities of tiny particles in turbulent air, creating a picture of the rough air ahead.

The sensor now only “sees” straight ahead. But the goal is to be able to scan horizontally and vertically to get a three-dimensional picture of the turbulence. At this point, the laser-based sensor can see approximately four miles ahead, which for a commercial jet translates to a warning time of 10 to 30 seconds.

“They’d like five minutes,” says Rod Bogue, project manager at NASA’s Dryden Flight Research Center in Edwards, Calif. “But 10 to 30 seconds is better than nothing.” Just ask anybody who’s been through turbulence lately.