Icing strategies for the coming winter

 - October 18, 2006, 5:51 AM

Apparently, it’s just a time-honored myth that the Inuit language of native Alaskans has as many as 400 different words covering all forms of frozen precipitation. In fact, there are about a dozen, just like in English. But ask professional pilots who have been faced with removing thick coatings of stubborn frozen stuff from their airplanes before a flight, and you’ll likely find a few more choice words–most of which are not printable–to add to the list.

Last month, the NTSB released cockpit transcripts from the final moments of a Cessna Citation V flight that crashed on approach to Pueblo, Colo., in February. The crew discussed the extent and configuration of icing on the wings’ leading edges just before they lost control of the airplane. If the Safety Board determines that icing is the probable cause of that accident, it will be the first time in several years that a jet has fallen victim to in-flight icing. But snow and ice accumulation before an attempted takeoff is another matter.

One high-profile fatal accident last winter and a few close calls have placed preflight ice and snow removal on the front burner at flight departments, charter operators and fractional providers. In fact, the FAA issued an airworthiness directive last winter mandating that the crew perform not just a visual inspection but also a tactile examination of the wing leading edge and tail surfaces before takeoff. And last month, the agency supplemented that directive with Notice 8000.308, which an FAA press release says “provides guidance and infor-mation for aircraft operators regarding the evaluation of de-icing/ anti-icing programs. This notice applies to Part 125 and Part 135 certificate holders that have elected to operate with a program approved under Part 121.629(c).” The entire notice is available at http://web. nbaa.org/public/ops/n8000-308.pdf.

Parallel issues of safety and cost are at the top of managers’ agendas this year. Several flight departments have devoted time and resources to educating their pilots about de-icing and anti-icing in a two-prong effort to ensure safe operation while trying to keep expenses within reasonable limits. NASA has developed a free online course called “A Pilot’s Guide to Ground Icing.” Intended primarily for professional pilots who make their own de-icing and anti-icing decisions, the course is part of a series of training aids developed at NASA’s Glenn Research Center and the first on ground icing. Developed by an international team led by NASA researchers, the program is available online at http://aircrafticing.grc.nasa.gov/courses.html.

Ensuring Safety

Foremost is the need to ensure that if the airplane needs to be de-iced, the task will be done properly and effectively, with sufficient holdover time from spraying to takeoff. After that, it makes good fiscal sense for pilots to understand the most efficient and cost-effective techniques in snow and ice removal. For example, if there is a four-inch layer of slushy snow atop a layer of crusty ice, a soft broom or squeegee might be the best way to clear the top layer, leaving the stubborn ice underneath for the FBO’s heated-glycol sprayer.

A crew’s primary responsibility when it comes to deicing is to ensure that those spraying the fluid know what they’re doing and that holdover times are not exceeded between de-icing and takeoff. The old adage is, “Don’t think twice; de-ice.” Cost is secondary. Chip Claughsey, chief pilot for Cigna in Windsor Locks, Conn., told AIN, “I’m more than willing to pay what it costs, but I need to know that the FBO has the appropriate type of fluid to give us enough holdover time, the right equipment–a cherry picker to get at the high tails on our Falcons, for example–and that the line crews have the proper training.”

Besides the NASA program, aircraft operators have a number of options to familiarize themselves with de-icing procedures. The National Air Transportation Association (NATA) sponsored a series of four one-day seminars conducted last month by consultant Walter Randa, who founded Montreal-based Leading Edge Aircraft Deicing Specialists in 1997 to educate flight crews about de-icing and anti-icing procedures. The curriculum includes discussion of 12 pertinent topics, including details of ground-icing conditions; aircraft inspections; methods and procedures; holdover guidelines; and recognizing the telltale signs of “fluid failures” on the airframe.

In addition, attendees can update their training online and share knowledge with their colleagues. NATA recommends the program for FBO line technicians, other ground personnel, flight crews and dispatchers. Sessions were held last month in Windsor Locks, Conn.; Dayton, Ohio; Denver; and Milwaukee. Leading Edge can also arrange on-site seminars at individual flight departments, and an online version of the course is available.

Last month, NATA joined NBAA and GAMA in an industrywide promotional program on de-icing and anti-icing procedures. Its goal is to raise awareness of the issue among pro- fessional crews this winter.

Talk to FBOs Early

Randa recommends that aircraft operators look ahead and discuss de-icing issues with ground-service providers at airports where they make regular stops. There are several pertinent questions to ask, and getting answers up front can head off disruptions to trip schedules and disputes over fees.

He recommended a list of questions to discuss with an FBO.

First, it pays to avoid the de-icing issue altogether if possible. Randa suggests asking if the airplane can be stored overnight in a heated hangar. If not, and if heavy snow is in the overnight forecast, the operator should ask whether it will be possible to broom clean the airframe before spraying starts the next morning. Manually removing most of the coating of snow and ice can reduce the amount of deicing fluid needed to make the airplane safe for flight.

Next, there should be discussion about what type of fluid is available. Most de-icing is done with Type I fluid, a blend of water and glycol, an alcohol-based fluid used in automotive anti-freeze coolant. Type I is usually mixed with water and heated to about 150 degrees F, then power-sprayed on the airframe wherever icing has adhered to the surface. The heat and pressure removes the frozen coating, and the glycol content keeps the residual spray from refreezing.

The next question might be how far from the departure end of the runway the de-icing location is. There are predetermined amounts of time allowed between de-icing and takeoff during times of freezing precipitation. A so-called holdover table, or HOT, defines how much time is permissible based on ambient air temperature and precipitation type. Other variables may include aircraft type. NATA publishes HOT guidelines, which are updated annually. For information on the latest numbers for this winter, contact NATA at www.nata.aero.

The guideline parameters also include what type of fluid is used. Type I fluid is designed thin enough to flow off the airframe at takeoff speed. The venerable concoction of glycol and other elements has been around for more than 50 years, but so-called anti-icing fluids, including Types II, III and IV, have longer holdover times. That’s because they have a thicker consistency designed to adhere to the aircraft surface for longer periods of time and at higher speeds.

It’s also important to know what equipment the line crew has for applying the fluid–such as ensuring they have a lift-bucket truck to reach tall T tails. Also, one ought to know if the de-icing trucks have multiple tanks and are able to spray both Type I de-icing fluid and another grade of anti-icing fluid if necessary.

Safety Procedures

As far as line crew training is concerned, the NATA Safety First program includes sections on de-icing procedures as part of its safety module. The de-icing/anti-icing segment includes a 40-minute video portion, followed by a written section spanning about two hours–then discussion and testing. NATA director of safety management Amy Koranda said the section on de-icing and anti-icing totals between five and 10 hours, depending on how extensive the FBO’s de-icing operations are.

NATA is applying its Safety Management System feedback to de-icing procedures to ensure that all system participants can share the lessons each operator learns. Koranda’s advice to FBOs is to ensure that de-icing training is effective through proper testing of line personnel after the fact and to make sure the policies and procedures are in writing and that everyone reads them.

For aircraft operators, Koranda advised that they ask the FBO about its initial and recurrent training. She also said to ask if the FBO performs de-icing under contract for airlines on the airport. That would indicate (but not guarantee) that the airline has vetted the FBO’s de-icing equipment, personnel training, policies and procedures. It might also indicate that the line personnel have more regular experience in de-icing operations. An FBO that caters only to general aviation might not get the opportunity to practice de-icing procedures under real-world conditions, even if the airport saw occasional snow and ice, unless its responsibilities included regular airline flights.

It might not be practical for an aircraft operator to have proactive discussions early in the season with any and all FBOs that might, someday, be in the position to de-ice the airplane. But experienced aircraft operators and experts in de-icing technology and procedures agree that chief pilots and/or dispatchers would be well advised to broach the subject with FBO general managers at their regular cold-weather haunts.

And for ad hoc trips, it is wise to bring up de-icing prices and policies at first contact. It might be that the potential cost of de-icing the airplane could dictate a change of schedule later.