NTSB Factual Report

On January 11, 2017, about 0913 central standard time (all times cst), a Cessna 182T bearing Canadian registration C-GTBI, was substantially damaged during landing on runway 18 at the Green Bay-Austin Straubel International Airport (GRB), Green Bay, Wisconsin, following an in-flight structural icing encounter. The pilot, who was the sole occupant, was not injured. The airplane incurred structural damage to the forward fuselage and firewall. The aircraft was registered to Falconair Ltd., and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a business flight. Visual meteorological conditions prevailed for the flight, which was not on a flight plan. The flight originated from Sawyer International Airport (SAW), Marquette, Michigan about 0505, with Falls International Airport-Einarson Field (INL), International Falls, Minnesota as the intended destination.

About 30 minutes into the flight, controllers advised the pilot that moderate icing was reported over Houghton County Memorial Airport (CMX), near Hancock, Michigan. The pilot advised controllers that he would alter his course more to the southwest. About one hour into the flight he noticed ice accumulation on the wing and landing gear and advised controllers that he wanted to divert the flight. He stated that heavier ice accumulation came on quickly and obscured his vision through the windshield.

The pilot diverted to Lakeland Airport/Noble F. Lee Memorial Field (ARV), near Woodruff, Wisconsin. He circled ARV in preparation for landing, but the weather conditions at ARV deteriorated to instrument meteorological conditions. He then advised controllers that he was proceeding south to reach visual meteorological conditions. He opted to land at GRB and received approach guidance from GRB approach controllers. He stated that when 30 ft above the runway, he applied flaps for landing, the airplane stalled, and a hard landing occurred.

Radar track data for the final portion of the accident flight showed the airplane made a left turn near Manitowish Waters, Wisconsin, and proceeded on a south-southeast heading toward ARV at an altitude about 2,700 ft. above mean sea level (msl). The airplane maneuvered near ARV, at altitudes varying from 3,000 ft. msl to 1,900 ft. msl, for about 45 minutes before proceeding south. The airplane ultimately turned east toward GRB before making an approach to runway 18 at GRB.

Current Icing Potential (CIP) product information for the area where the pilot reported the icing encounter showed no icing at 3,000 ft. msl. The one-hour Forecast Icing Potential (FIP) icing forecast, valid at 0700 and applicable to 3,000 ft. msl, showed the icing severity as trace ice, an icing probability of about 10%, with the supercooled liquid drop potential as unknown.

For the same location and time, but at a higher altitude of 5,000 ft. msl, the CIP icing severity was light to moderate, the icing probability was 40-50%, with the supercooled liquid drop threat was unknown. The one-hour FIP icing forecast, valid at 0700 and applicable to 5,000 ft. msl, showed the icing severity as light, an icing probability of about 30%, with the supercooled liquid drop potential as unknown.

An Area Forecast that included the state of Wisconsin, Lake Superior and the Upper Peninsula of Michigan was issued at 0445. With regard to the approximate location of the accident aircraft's initial icing encounter: the portion of the Area Forecast directed toward the northwestern portion of Wisconsin forecasted overcast clouds at 3,000 ft msl with cloud tops to 25,000 ft., visibility of three statute miles, light snow; the portion of the Area Forecast directed toward the northeastern portion of Wisconsin forecasted overcast clouds at 6,000 ft. msl with cloud tops to 27,000 ft., broken clouds at 2,500 ft. msl beginning at 0700; the portion of the Area Forecast directed toward the western portion of Lake Superior and Upper Peninsula of Michigan forecasted overcast clouds at 2,000 ft. msl with cloud tops to 25,000 ft., visibility of three statute miles, scattered light snow showers.

NTSB Probable Cause

The airplane’s encounter with unforecast icing conditions, which led to structural icing that obscured the pilot’s vision, an aerodynamic stall, and a subsequent hard landing.