CAT - Laser et remedium? Curt Lewis

Laser could help pilots 'see' clear air turbulence coming

Pilots can avoid some turbulence, but clean air turbulence is currently undetectable. New technology being tested by Boeing may change that.

It can feel like the perfect day if you're in a jetliner above the clouds. But it's what you can't see that's the leading cause of injuries in flight.

Airliners around the world can encounter serious turbulence -- in some cases, turbulence that's violent enough to send passengers and drink carts into the ceiling.

Turbulence can be both expected and unexpected. The clear air turbulence is the unexpected part. You really can't see it because it's not associated with any sort of weather. That's why airlines ask you to remain buckled in your seat when you're not up and around the cabin.

Boeing is testing new technology aimed at helping pilots detect that turbulence in time to adjust altitude to avoid it. At the Montana Aviation Research Company in remote St. Marie, Montana, Boeing's test employs the ecoDemonstrator. It's a 777 freighter turned into a test plane.

JAXA, Japan's space agency, has developed technology on board the airplane to detect the, until now, undetectable. It's designed to deliver a warning up to a minute in advance of impending clear-air turbulence.

"So this would be integrated into a forward display ... warning the pilots they're coming up on turbulence," said Boeing Flight Test Director Ian Mahler. "And there will actually be a little pop up over here that has a countdown that says severe turbulence, moderate turbulence or wind shear, in 59, 58. It will countdown in seconds. And give you a warning of exactly when it will hit."

On the left side of the plane is something called a fairing. It's also known as a blister because it looks like a bulge coming from the smooth, round exterior of the plane. On the outside of that fairing is a window which protects a liquid-cooled infrared laser called LIDAR.

LIDAR is the same type of technology fired down out of the bottom of special airplanes thousands of times a second to create detailed photographic-like images of the earth. It's used to find earthquake faults on land and can be used to find what are essentially faults in the air: inconsistencies in the way air moves or turbulence.

The beam goes out the side, reflects off a mirror and is focused miles ahead of the airplane. It's detecting tiny particles in the air called aerosols. But when those particles seem to slow down, speed up, or move up and down, that's the warning.

Then the question becomes, where do you find clean air turbulence to test it?

"We wanted to find something where the turbulence was very predictable," said Mike Carriker, Boeing's top pilot for product development. "So over Kansas, over Garden City, Kansas, we found an altitude about 24,000 to 27,000 feet where the wind was just terrible. Just shaking everywhere. But it was smooth below and smooth above, so we could get down below it and climb up and see that it was ahead of us, and then see that it was going to quit as we went out the other side."

"And during our testing we validated, and it was absolutely incredible, that we saw it go five, four, three two one. And then the people started feeling the bouncing. So the technology works," said Mahler.

"And the airplane's doing six miles a minute, so you'd have to find it 30 or 40 miles out in front of you. That's the technological end goal because we'd like to have enough time to put the carts away," said Carriker, explaining that while it's important for passengers to buckle up, carts could fly up and hit someone.

Now, the job is to make the system smaller, while making it look out miles farther where it's hoped it will become a routine safety tool in the cockpit.