Tuesday, February 10, 2009
The quantity and quality of information have improved, but icing is ever a deadly foe
|Ten years ago, the National Aviation Weather Program Council met in Washington, D.C., to develop ideas that could be turned into practical steps toward reducing the number of weather-related aircraft accidents. Regarding in-flight icing, the group—which included FAA, Department of Defense, NASA, Department of Commerce, Department of Agriculture and NTSB representatives—concluded that better observation systems were needed for detecting icing, and weather forecasts should present icing hazards in clear, easily understood formats. |
|DEALING WITH AN ICING ENCOUNTER. Pilots need to recognize the hazards of flying in frigid weather conditions and prepare themselves for dealing with in-flight icing.|
Ten years ago, the National Aviation Weather Program Council met in Washington, D.C., to develop ideas that could be turned into practical steps toward reducing the number of weather-related aircraft accidents. Regarding in-flight icing, the group—which included FAA, Department of Defense, NASA, Department of Commerce, Department of Agriculture and NTSB representatives—concluded that better observation systems were needed for detecting icing, and weather forecasts should present icing hazards in clear, easily understood formats. Better training was needed so that pilots could identify in-flight icing conditions sooner, enabling them to take earlier avoidance action. The group identified the need to reduce the costs of developing and certifying in-flight deicing equipment to make it affordable for GA aircraft.
In the decade since the council’s initiatives were put forth, there has been an evolutionary improvement in the availability of information about icing conditions that has coincided with overall improvements in the quality and quantity of meteorological information. Currently, for example, on the Internet, the National Weather Service’s Aviation Digital Data Service has a section devoted to graphical displays of information related to in-flight icing. It’s easy to see where icing may likely be encountered using the graphical display of current icing advisories, a U.S. map showing freezing levels at a glance and an icing severity map (adds.aviationweather.noaa.gov
Unfortunately, the improvement in available information hasn’t translated into the elimination of accidents involving icing. Even when a pilot is fully aware of the likelihood of an icing encounter and comes up with what seems to be a reasonable plan for dealing with the hazard, the situation can easily become untenable.
On December 26, 2006, at 3:55 p.m., a Cessna 414 crashed at John Murtha Johnstown-Cambria County Airport in Johnstown, Pa. The plane was on an IFR flight plan from Morgantown Municipal-Walter L. Bill Hart Field in Morgantown, W.V., to Teterboro Airport in Teterboro, N.J. The 414 medical aircraft was traveling to Teterboro to pick up a patient. The pilot and flight nurse were killed.
The pilot contacted Cleveland Center at 3:21 and reported climbing through 3,400 feet for 8,000 feet. The pilot was told to proceed direct to the Stillwater VOR, direct Teterboro and maintain 9,000 feet. The pilot acknowledged the clearance.
At 3:27, the pilot requested a climb to 13,000 feet. She radioed, “We’re getting iced-up pretty bad here.” The controller then cleared the airplane to 13,000 feet and asked about the nature of the icing. The pilot replied that the outside air temperature was “about minus three...and we’re getting moderate mixed [icing].”
At 3:29, the pilot radioed the controller, “I can’t climb any farther,” and requested 7,000 feet. The controller approved a descent to 5,000 feet, adding, “If you want to level off on descent, that’s approved.” About two minutes later, when at 7,000 feet, the pilot radioed, “We’re keeping up with it; I’d like to stay here for now.” The controller approved the request.
At 3:38, the controller radioed to ask how the flight was handling the ice; the pilot stated, “We’re just barely keeping up with it.” The pilot then requested a descent to 5,000 feet, to be followed by 3,000 feet as the terrain got lower, progressing eastbound. The controller advised the pilot, “I can’t do three out in that area,” and cleared the pilot to descend to 5,000 feet. The pilot then responded, “I’ll keep that [3,000 feet] as an option for now...I may get to a point where I can’t hold my altitude...maybe making an approach to an airport just to get me down to...2,500 feet to shed the ice off and go missed and then continue on my way.” The controller said, “Right now, you’re pretty much lined up for the localizer at Johnstown, so if you need to do that, just let me know.” The pilot acknowledged.
About 80 seconds later, the pilot requested the “localizer at Johnstown, and see if I can get some of this off, and then I’ll continue on my way.” Over the next several minutes, the controller coordinated the approach sequencing with another controller, and at 3:42, provided a heading for the ILS runway 33 approach at Johnstown. The controller also gave the pilot the airport weather: winds from 300 degrees at 15 knots (gusting to 20 knots), visibility at seven miles, a 300-foot overcast, temperature of 0 degrees C, dew point of minus-1 degree C and a ceiling variable from 200 to 600 feet. The pilot said, “If our ice comes off, we intend to go missed [approach].”
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