Atmospheric and Climate Science Directorate

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Ensuring Safe Flights in Northern Climates

Aircraft Icing Research

Aircraft icing is one of the biggest hazards to aviation in North America, particularly in the northeast. Aircraft that operate in winter conditions can encounter rapid ice accumulation that is so severe that they cannot maintain level flight. Ice accumulates on the leading edges of the aircraft – reducing lift, while at the same time increasing drag dramatically. The combination of decreased lift and increased drag can lead to disaster. Several major aircraft accidents in recent years have been attributed to aircraft icing. Scientists at the Meteorological Service of Canada MSC are international experts when it comes to understanding and measuring aircraft icing. They have conducted studies in Canada’s most ice-prone maritime and continental locations - near St. John’s, Newfoundland, and the Great Lakes. MSC’s researchers have logged hundreds of hours flying through freezing drizzle, freezing rain and ice-laden clouds, in order to improve scientific understanding of the meteorological conditions under which icing occurs.

Icing that occurred on probes of the Convair-580 during a flight on February 19, 2003 at Mirabel airport in Quebec.The probes measure the size, shape and concentration of particles.

In 1998, when the U.S. - Canadian Aircraft Icing Research Alliance ((AIRA)) was formed, MSC researchers were at the centre of a research plan that included NASA, the Canadian National Research Council, Transport Canada and the U.S. Federal Aviation Administration. The goal was to develop and implement an integrated aircraft icing research plan. The role of MSC on this team was to conduct in-cloud measurements of icing environments, develop techniques to remotely detect icing conditions, and to improve methods of forecasting in-flight icing. The first major study under (AIRA), the Alliance Icing Research Study (AIRS), took place in the winter of 1999-2000. MSC scientists, using a variety of direct and remote sensing instruments, made an extensive array of ground and in-flight measurements of icing rates.

The windshield of the NRC Convair-580 after returning from an experimental flight during which measurements of in-flight icing rates were made.

This research has resulted in a large, comprehensive data set that characterizes aircraft icing conditions, and in particular, supercooled large droplet conditions that are outside the current aircraft certification requirements. A follow-up study, AIRS II, is planned and attracting interest from a wider range of participants extending beyond North America.

Using MSC’s numerical weather prediction models, scientists have developed new algorithms, and quantitatively evaluated them for predicting icing. An Airport Vicinity Icing and Snow Advisor (AVISA) currently under development, showed promising results during initial testing in the winter of 2002-2003. MSC scientists are applying their research to new design criteria for commercial aircraft, and innovative products that will ultimately result in safer flights for us all.

The National Research Council’s (NRC) Convair- 580 is the best-instrumented aircraft in the world for in-cloud microphysics measurements.

“MSC's accomplishments in icing and cloud microphysics are worldclass and have been critical to the Aviation Rulemaking Advisory Committee's drafting of proposed airworthiness requirements for safe aircraft operations in freezing drizzle and freezing rain conditions.”
Eugene G. Hill
Chief Scientific and Technical Advisor
Environmental Icing Federal Aviation Administration USA

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