November 29, 2010

With the arrival of winter weather, it’s crucial for operators to familiarize themselves with the proper procedures for dealing with aircraft icing. When temperatures drop below two degrees Celsius, ice, frost or frozen slush can form on an aircraft’s wings both on the ground and in the air, presenting a major hazard.

“Every operator needs know how to deal with icing, even if you’re based in a Sunbelt state,” said NBAA’s Doug Carr, vice president, safety, security & regulation, “The weather can change quickly this time of year and even if you only make one flight per season into an area known for icing, proper pre-flight planning and current knowledge of icing risks are essential.”

Don’t Underestimate the Risks of Icing

Ground icing is often the most complex – and most often underestimated – problem for pilots.

“Pilots that have a successful takeoff with frost on the wings can have a negative learning experience,” said Kurt Blankenship, a long-time ice research pilot and safety specialist with NASA’s Glenn Research Center. “They simply don’t know how close to the edge they really were and assume they were flying safe. There are some accidents that reflect that.”

Blankenship cited a 2002 accident at Birmingham International Airport in the UK in which a Bombardier Challenger 604 crashed during takeoff. Because one wing was clear, the pilots assumed the frost buildup on one of the wings to be within safe range, but it caused the aircraft to uncontrollably roll, killing everyone onboard.

Even highly conscientious pilots who request deicing can have difficulty, because the procedure’s effectiveness varies considerably depending on several variables.

“There are a lot of nuances to ground deicing,” said Blankenship. “The fluid needs to be heated to a certain temperature, and of course frost on the windscreen can affect your visibility.”

Industry leaders and experts agree that the key to minimizing the risks from icing is to plan ahead.

“In adverse weather, pilots should anticipate the need for deicing and report to the airport earlier than usual,” said Eric Bossard, manager of BASF’s flight department and president of the Morristown Aviation Association. “Make sure you notify the FBO and discuss their protocol while explaining your requirements. You should also have a copy of the OEM’s deicing recommendations that you can review with the applicator.”

While the risks of ground icing are too often underestimated, experts advise pilots not to overreact to airborne icing. An aircraft affected by airborne icing is flyable and controllable, just in a reduced speed range. Icing can increase drag and reduce lift so pilots may need to increase thrust in order to maintain airspeed.

NBAA has several resources for operators to learn about procedures for various forms of icing. In an NBAA webinar, Blankenship’s NASA colleague, Dr. Judith Van Zante, discussed the risks of icing, ice protection systems and best practices. NBAA has also supported regional groups in hosting education sessions on winter operations the last two years.