Press Release 04-029
New Radar System May Help Airplanes Avoid In-Flight Icing
March 10, 2004
Arlington, Va.—The buildup of ice on airplanes in flight is a
major winter hazard for small and commuter planes. But scientists
at the National Center for Atmospheric Research (NCAR) in
Boulder, Colo., are testing a new system this month that may
pinpoint water droplets in clouds that cause icing, potentially
enabling pilots to avoid dangerous areas.
The system, known as S-Polka, combines two existing radars that
use different wavelengths. By studying the differences between
the images that are reflected back to each radar, scientists hope
to find tiny water droplets that are difficult to distinguish
using either radar alone. The project is funded by the National
Science Foundation (NSF), which is NCAR's primary sponsor, and
the Federal Aviation Administration (FAA).
"NSF continues to invest in fundamental science while
recognizing opportunities for the broader impacts of the research
it supports," said Cliff Jacobs, program director in NSF's
division of atmospheric sciences. "This new effort is a clear
link between knowledge that benefits society and fundamental
studies of our atmosphere."
"This will take out a lot of the guess work," explains Marcia
Politovich, director of NCAR's icing program. "We think it will
show exactly where the water is. That information could
ultimately turn into an important warning system for pilots."
Scientists and engineers at NCAR are deploying S-Polka through
the end of March at NCAR's Marshall facility southeast of
Boulder. The system consists of a powerful polarized radar,
known as S-Pol, which operates at a frequency of 3,000 MHz, and a
polarized Ka-band radar, which operates at 35,000 MHz. The S
Pol radar produces detailed images of clouds and precipitation,
whereas the Ka-band radar can detect weaker clouds that are not
precipitating. By comparing the images from each radar,
researchers hope to find areas in clouds that harbor water
Finding cloud water droplets has long posed a scientific
challenge. The droplets are 50 microns or less in diameter, just
one-tenth the size of raindrops. They may remain in liquid form
even when the surrounding air temperature drops below freezing.
The droplets are most dangerous at that time because they adhere
to aircraft wings and then freeze, reducing the plane's
Unfortunately, existing radar often cannot detect the droplets if
they are surrounded by larger raindrops or snow. Even if small
cloud particles are detected, a radar signal cannot indicate
whether they are droplets or ice crystals.
"When it comes to cloud particles, we can't interpret the
standard radar echo," explains NCAR's Jothiram Vivekanandan, the
lead scientist on the project. "This research is very
The two radars have been mounted on a single pedestal at the
Marshall facility. They are precisely aligned to look at the
same defined area at the same time. Researchers will compare the
radar images with data collected from a University of North
Dakota Citation research airplane flying in the test area to
determine whether the radar system is pinpointing water droplets.
After data are collected this month, the researchers will focus
on identifying and measuring droplets within the radar images
accurately. If all goes well, the instrument will undergo final
tests in a couple of years before being made available to
Notable Icing Crashes:
- In-flight icing downed the small plane carrying 1950s rock
and roll legends Buddy Holly, Ritchie Valens and The Big Bopper
(J.P. Richardson). All three musicians and the pilot died when
their plane crashed soon after take-off from Mason City, Iowa, on
Feb. 3, 1959.
- An American Eagle ATR-72 went into a high-speed dive and
crashed near Roselawn, Ind., on Oct. 31,1994. As the plane
circled for a half hour waiting to land in Chicago, ice forming
on the wings caused the crew to lose control. None of the 68
people aboard survived.
- An Embraer 120RT en route from Cincinnati crashed on
approach to the Detroit airport on Jan. 9, 1997, killing all 29
people on board. At the time, other aircraft in the area were
reporting icing minor to very heavy.
Cheryl Dybas, NSF, (703) 292-7734, firstname.lastname@example.org
Anatta , NCAR, (303) 497-8604, email@example.com
Cliff Jacobs, NSF, (703) 292-8520, firstname.lastname@example.org
The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2016, its budget is $7.5 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives more than 48,000 competitive proposals for funding and makes about 12,000 new funding awards. NSF also awards about $626 million in professional and service contracts yearly.
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