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Monitoring
Wake Vortices for More Efficient Airports
Transportation
Originating Technology/ NASA Contribution
Wake vortices are generated by all aircraft during
flight. The larger the aircraft, the stronger the wake,
so the Federal Aviation Administration (FAA) separates
aircraft to ensure wake turbulence has no effect on
approaching aircraft. Currently, though, the time between
planes is often larger than it needs to be for the
wake to dissipate. This unnecessary gap translates
into arrival and departure delays, but since the wakes
are invisible, the delays are nearly inevitable.
If, however, the separation between aircraft can be
reduced safely, then airport capacity can be increased
without the high cost of additional runways. Scientists
are currently studying these patterns to identify and
introduce new procedures and technologies that safely
increase airport capacity. NASA, always on the cutting
edge of aerospace research, has been contributing knowledge
and testing to these endeavors.
Partnership
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WindTracer
detects wind hazards such as windshear, microbursts,
gust fronts, turbulence, crosswinds, and wake
vortices that can compromise the safety of
an aircraft. |
NASA’s Langley Research Center, working with the FAA
on a joint program known as the Wake Turbulence Research
Program, conducted research on the wake vortices at
the Denver International Airport.
Langley scientists collected acoustic signature data
from the wakes of landing aircraft and then characterized
these signatures for a variety of aircraft types in
various conditions. Two large, precision microphone
arrays were placed on the ground beneath the glide
slope for a runway, one operated by NASA and the other
by the German Aerospace Center, or Deutschen Zentrum
für Luft- und Raumfahrt. Because there are numerous
unknowns about the acoustic signatures of wakes, a
truth sensor was needed to tell NASA the location of
the wake, allowing the measurements to be properly
characterized.
The research teams used WindTracer as a ground
truth sensor for these wake vortex acoustic tests.
WindTracer is manufactured by Coherent
Technologies, Inc. (CTI), the recipient of a Langley Small
Business Innovation Research (SBIR) grant to develop this integral
piece of equipment. CTI is a privately held company
based in Louisville, Colorado, and is the only company
in the world that offers an infrared Doppler lidar
as a commercial product.
Product Outcome
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WindTracer
uses an infrared, eye-safe laser, with precision
pointing and scanning capabilities, to bounce
off the air particulates. It poses no risks
to pilots. |
WindTracer uses an infrared, eye-safe laser, with precision
pointing and scanning capabilities, to bounce off the
natural particulates floating in air. The light reflected
back to the system measures the wind and tracks the
strength and location of the aircraft vortices. The
technology has been developed over the past decade
by CTI and is applied to a variety of airport and airliner
wind hazards, as well as measurement applications.
WindTracer detects wind hazards such as windshear,
microbursts, gust fronts, turbulence, crosswinds, and
wake vortices that can compromise the safety of an
aircraft. It detects these hazards and transmits real-time
data to air traffic control display monitors, providing
immediate audio and visual alerts to the staff when
dangerous conditions arise. This information can be
quickly relayed to the pilots of arriving or departing
aircraft who can then adjust their patterns to avoid
the hazards.
A WindTracer unit is currently set up at the Hong Kong
International Airport, which is located near Lantau
Island, a large mountainous island that often experiences
windshear and turbulence. Other wind hazards arise
due to frontal passages and sea breezes. These wind
conditions are potentially hazardous to landing and
departing aircraft.
The device is operated by the Hong Kong Observatory
(HKO), one of the world’s leading meteorological organizations.
It forecasts weather and issues warnings on weather-related
hazards at the airport and within a designated airspace
over the northern part of the South China Sea. To enhance
the safety of aircraft landing at and taking off from
the airport, the HKO issues alerts of low-level windshear
and turbulence. A Terminal Doppler Weather Radar network
of over 20 anemometers,
2 wind profilers, and WindTracer are used to assist
in the detection and warning of windshear and turbulence.
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WindTracer
profiles winds and detects windshear, turbulence,
and aircraft wake vortices at both airports
and onboard commercial airliners. |
It is also being employed successfully by the St. Louis
International Airport, where it is used to observe
wake vortices produced by aircraft landing on specific
runways. It then provides data, which is used to validate
the safety of new capacity-enhancing procedures being
developed by the FAA.
Since its installation in 2003, the system has been
running unattended, with system operational modes being
automatically changed via an operator-defined schedule,
and remote access to the system via an Ethernet connection
enables mode and schedule changes to be affected without
the need for onsite staff.
The WindTracer was also used for the U.S. Department
of Defense’s (DOD) atmospheric dispersion survey conducted
in and around the Pentagon. The survey sought to improve
knowledge about the weather conditions
and movement of simulated airborne contaminants.
Knowledge gained about the airflow around the Pentagon,
and the associated transport of gases and their infiltration
into the building, will lead
the development for improved systems to protect other
DOD facilities.
The product has been proving itself useful around the
world, and it has the potential to revolutionize the
entire airline industry.
WindTracer® is a registered trademark
of Coherent Technologies, Inc.
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