By Charlene Porter
The National Center for Atmospheric Research (NCAR) has developed a turbulence-avoidance system for use in flight, allowing pilots to better detect and avoid patches of potentially dangerous air turbulence.
The U.S. Federal Aviation Administration (FAA) commissioned NCAR to develop the system, and it is in use at the airport in Juneau, Alaska. The developers will now work to adapt the system for other airports with notoriously severe turbulence, including those in the Rocky Mountains of the United States.
A similar NCAR system has been guiding pilots to smoother landings at Chek Lap Kok Airport in Hong Kong for a few years. An NCAR press release said airports in Norway and New Zealand are also in line for adoption of the turbulence-avoidance system.
Air turbulence is a fact of life in flying, but it is an especially common hazard in mountain cities, where air currents move over and around peaks in ways that create unpredictable patterns of updrafts and downdrafts, sometimes strong enough to knock a plane off its designated flight path. The FAA says turbulence is common, normal and potentially dangerous. If passengers or crew are moving about the plane, not fully strapped in, turbulence may throw them off balance and send them crashing about the cabin.
From 1980 through 2008, the FAA documented that U.S. air carriers had 234 turbulence accidents resulting in harm to passengers, crew or aircraft, with 298 serious injuries and three fatalities.
The turbulence-avoidance system uses a network of wind-measuring instruments and computational formulas to interpret rapidly changing atmospheric conditions.
“By alerting pilots to areas of moderate and severe turbulence, this system enables them to fly more frequently and safely in and out of the Juneau airport in poor weather,” said Alan Yates, an NCAR program manager who helped oversee the system’s development. “It allows pilots to plan better routes, helping to reduce the bumpy rides that passengers have come to associate with airports in these mountainous settings.”
In Alaska, the system is known as the Juneau Airport Wind System (JAWS), and it allows the airport to keep planes moving through periods of turbulence as it highlights corridors of smooth air for safe takeoffs and landings.
“The JAWS system has nearly eliminated all the risk of flying in and out of Juneau,” says Ken Williams, a Boeing 737 captain and instructor pilot with Alaska Airlines. “I wish the system would be deployed in other airports where there are frequent encounters with significant turbulence, so pilots can get a true understanding of what the actual winds are doing on the surrounding mountainous terrain as you approach or depart.”
JAWS has been of particular benefit to Juneau because turbulence could often become severe enough to ground planes from flying. That’s a serious inconvenience when Juneau is accessible to the rest of Alaska only by air or boat.
To prevent those shutdowns at Juneau’s airport, the NCAR team used research aircraft and computer simulations to determine how different wind patterns from the mountains and the ocean correlated with specific areas of turbulence near the airport. They installed anemometers (wind-speed measurement devices) and wind profilers at key sites along the coast and on mountain ridges.
The instruments around the airport transmit data multiple times every minute. Pilots can get near-real-time information about wind speed and direction; a visual readout shows regions of moderate and severe turbulence in the airport’s approach and departure corridors. The instruments are weatherproofed, and they can continue functioning even when exposed to extreme cold, wind and heavy icing conditions.
NCAR is a federally funded research and development center sponsored by the National Science Foundation. Significant additional support is provided by other U.S. government agencies, other national governments and the private sector.