NCAR Teaming with United Airlines on Turbulence Detection

United Airlines is evaluating a new turbulence detection system meant to alert pilots to areas of rough air while flying through clouds.

The system, designed by the U.S. National Center for Atmospheric Research (NCAR), uses a NEXRAD (next generation weather radar) turbulence detection algorithm, or NTDA, to analyze data obtained from the National Weather Service's network of NEXRAD Doppler radars.

NTDA uses these data to analyze the distribution of winds in the atmosphere after removing factors that can contaminate measurements, such as sunlight, nearby storms, or even swarms of insects flying near the radar dish. It also averages a series of measurements to improve the reliability of its turbulence estimates.

The resulting real-time snapshot of turbulence can be datalinked to aircraft and made available to airline meteorologists and dispatchers via a Web-based display.  At this time, however, pilots are only receiving text printouts as seen in the second example below.

NCAR Turbulence Display

Source: Research Applications Laboratory, NCAR

NCAR Turbulence Printout

Source: Research Applications Laboratory, NCAR

The NTDA is being tested until October by a group of United crews who fly routes east of the Rockies, and they report that the system provides them with accurate information about turbulence that is not available from any other source.

United's chief technical pilot, Captain Rocky Stone, said, "The messages I've received in the cockpit gave a very accurate picture of turbulence location and intensity."

Depending on the results of this year's tests, the next step may be to expand the system to additional United aircraft or other airlines, according to NCAR.

NCAR scientist John Williams anticipates that, by 2011, the NTDA will provide input to a system over the contiguous U.S. and will update comprehensive turbulence "nowcasts" every 15 minutes.

This year's tests build on smaller-scale tests with United Airlines in the summers of 2005 and 2006 that showed it was possible to successfully detect moderate-or-greater turbulence more than 80 percent of the time. NCAR scientists have refined the NTDA since then, and expect that this year's demonstration will show additional improvements to the system's accuracy.

The NTDA does not measure clear-air turbulence, such as that caused by the jet stream or by wind flowing over mountainous terrain. But about two out of every three turbulence encounters are associated with clouds and storms, the focus of NTDA detection.

Turbulence has major impacts on aviation. According to a review of National Traffic Safety Board data from 1992 to 2001 by the National Aviation Safety Data Analysis Center, turbulence was a factor in at least 509 accidents in the United States, including 251 deaths (mostly in the general aviation sector). Additionally, the FAA Joint Safety Analysis Team estimated that there are more than 1,000 minor turbulence-related injuries on commercial aircraft annually.  Airlines lose millions of dollars every year due to turbulence because of injury claims, delays, extra fuel costs, and aircraft damage.  09-21-2007.

Click here to become a registered Flt Tech Online subscriber and receive headlines delivered to your e-mail each week

Click here to go back to the headlines