Icing Awareness

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]."

The controller then coordinated with Johnstown Tower and received a more current weather observation. At 3:45, the controller advised the pilot that the weather included an overcast cloud layer at 500 feet, temperature of 0 degrees C, dew point of minus-1 degree C and visibility at four miles. A minute later, the controller provided a final vector and cleared the pilot for the ILS runway 33 approach. At 3:49:36, the controller radioed that the plane was established on the localizer, radar service was terminated and the pilot should contact Johnstown Tower on frequency 125.75.

At the time of the accident, the tower was staffed by an ATC supervisor, specialist and trainee. Because neither the pilot nor Cleveland Center had declared an emergency, the trainee was the primary controller, backed by the supervisor. At 3:49:52, the pilot reported that the airplane was on the ILS for runway 33, and the trainee asked the pilot if she was going to execute a missed approach or a full-stop landing. The pilot answered, "It depends if my ice comes off or not...if the ice does not come off, we're gonna land." The tower trainee replied, "Roger, and keep me advised." There were no further transmissions from the pilot.

According to the tower supervisor, just before the airplane broke out of the clouds, he told the trainee to provide the pilot with the current winds. At 3:54:13, the trainee radioed, "Wind check three one zero at 17, gust 21."

According to the tower supervisor, who was using binoculars, he saw the plane break out of the clouds about 300 feet above the ground, right of course, approximately over taxiway B. The airplane appeared to be turning slightly to the right and climbing, and all three controllers commented that they thought the airplane was executing a missed approach. The supervisor said, "All of a sudden, the airplane made a rapid turn to the left, toward the runway, and began dropping like a rock, just dropping." The supervisor saw that the landing gear wasn't down and told the trainee to warn the pilot. At 3:54:21, the trainee radioed, "Check wheels down."

At 3:54:23, when the airplane was at about 75 to 125 feet, the supervisor radioed, "Go-around, go-around, go-around." The supervisor then saw the airplane make a "hard" landing about 2,000 feet beyond the runway threshold, on the left side of the runway. He saw a "puff of dust" and thought it had landed half on/half off the runway. He then observed the plane take off again "almost perfectly; it flew straight ahead" for 2,000 to 3,000 feet, and the landing gear was down. The plane then made a right turn "like in a midfield, right closed pattern," but then made "a steep nosedive into the grass infield."

According to company records, the pilot had a total of 3,547 flight hours (382 hours with the company). The C-414 was equipped with deicing wing boots, electric propeller deicing and an alcohol system for deicing the windshield. The pilot had contacted the Cleveland Automated FSS to file two flight plans, one for 9,000 feet, the accident flight, and another for 10,000 feet for the return flight from Teterboro to the Milwaukee area. The pilot also received weather briefings for each intended flight. The briefer advised of "moderate icing conditions from the freezing level to 17,000 feet" and "southwest Pennsylvania light to moderate rime icing." The briefer also reported temperatures in several states and said, "So, pretty much, you can expect ice...from about 2,000 feet, and you'll have to keep a close eye on it...they just say ’moderate ice' now." The briefer also noted that the lowest freezing level was at 6,000 feet.

Prior to the NTSB's arrival, the runway had been swept of debris and ice, and airplane remnants near the initial propeller strikes had been removed from the grass, but photos of the runway before it was cleared were provided by an initial responder. According to the responder, he "proceeded to runway 33 and noticed a large amount of ice pieces, which started at the 2,000-foot mark and extended in a ’V' pattern approximately for 1,000 feet." He also noted that the ice pieces ranged in size from "long horizontal pieces to golf ball and baseball sizes."

The NTSB determined that the accident's probable cause was the pilot's improper decision to abort the landing with a damaged plane. Contributing factors were damage from the plane's impact of the runway, the pilot's failure to lower the landing gear prior to the landing attempt and the in-flight icing conditions.    

Peter Katz is editor and publisher of NTSB Reporter, an independent monthly update on aircraft accident investigations and other NTSB news. To subscribe, write to: NTSB Reporter, Subscription Dept., P.O. Box 831, White Plains, NY 10602-0831.