CHI94MA072

The part 135 on-demand air taxi flight departed denver, Colorado, with a destination of columbus, Nebraska. Weather forecasts were for icing conditions along the entire route of flight. While en route, ATC advised the pilot of reported icing ahead. The pilot was cleared to climb to 19,000 feet to get on top of the clouds. The pilot reported 'some alternator problems,' and requested to divert to north platte, Nebraska. He then elected to divert to Mccook, Nebraska, due to the weather at north platte. ATC lost communication with the pilot during the diversion. Witnesses reported the airplane circled the Mccook airport twice. According to them, the airplane entered a bank of about 45 deg, then stalled. Subsequently, it traveled about 190 feet through a stand of trees before coming to rest. Witnesses reported the airplane was covered with ice. One-half inch of mixed ice was found on a piece of windshield. Both alternators had one phase in the stator winding shorted.

History of flight

On January 26, 1994, at 1515 central standard time (CST), a Cessna 421C, N5468G, operated by Sky Harbor Air Service, Inc., Omaha, Nebraska, crashed while making a visual approach to the McCook Airport, McCook, Nebraska. The airplane was destroyed. The commercial pilot and one passenger sustained fatal injuries, three passengers received serious injuries, and two passengers received minor injuries. The On-Demand Charter flight, operating under 14 CFR Part 135, originated at the Stapleton International Airport, Denver, Colorado, with an intended destination of Columbus, Nebraska. An IFR flight plan was filed, and instrument meteorological conditions prevailed at the time.

This flight was the return leg of a corporate/executive charter flight which had originated on January 24, 1994. On that day the pilot had flown the six executives from Columbus, Nebraska, to Denver. The airplane was kept in a hangar while it was in Denver. The pilot and airplane remained in Denver to transport the executives to Denver when their business was completed. The departure from Denver was planned for 1400 CST.

The pilot called the Denver Automated Flight Service Station (AFSS) at 0918 CST and received a weather briefing. The briefing included IFR conditions along the entire route, moderate turbulence, moderate rime and mixed icing to 16,000 feet, with pilot reports (PIREPS)of severe rime and mixed icing in freezing precipitation.

At 0954 and 1158 CST the pilot called Denver AFSS and received updates on the weather briefing he had received earlier. At 1258 CST he called Denver AFSS and filed two flight plans. The first was from Denver to Columbus, Nebraska, and the second was from Columbus to Omaha, Nebraska. He also received a weather update when he filed the flight plans. He was advised that an airmet was still in effect for IFR conditions along the entire route of flight with moderate rime and mixed icing from the surface to 18,000 feet. There were also pilot reports of icing along the route of flight.

The flight departed Denver Stapleton International Airport at 1344 CST. The air traffic control of the flight was transferred from Denver Departure Control to the Denver Air Route Traffic Control Center (Denver Center) at 1359 CST. The initial cruising altitude assigned was 10,000 feet. This was increased to 17,000 feet before the airplane reached 10,000 feet. The pilot reported reaching 17,000 feet at 1415 CST. During the climb, Denver Center reported receiving intermittent altitude information from the airplane's transponder.

At 1434 CST, Denver Center advised the pilot he was about to enter an area of reported icing from 14,000 to 19,000 feet. The pilot responded that the flight was in the tops of the clouds at 17,000 feet and not picking up any ice, and requested to climb to 19,000 feet. The pilot reported reaching 19,000 feet at 1438 CST.

From 1451 to 1454 CST there were several unintelligible radio communication attempts between Denver Center and the pilot. Communication was reestablished at 1454:49 CST which Denver Center reported as "real weak and broken." At 1454:58 CST, the pilot communicated, "...it looks like we're having some alternator problems, we're going to deviate, and the destination's going to be North Platte (Nebraska)." Denver Center cleared the pilot for the deviation direct to the North Platte Airport at 1455:04 CST. At 1456:12 CST, Denver Center cleared the pilot to descend to 7,000 feet at his discretion.

Denver Center gave the pilot the current North Platte weather at 1457:06 CST. The special observation was: indefinite ceiling five hundred, sky obscured; visibility one-quarter mile with heavy snow and fog. Denver Center offered to find a location that might have better weather. At 1457:29 CST the pilot replied, "...I'd appreciate that, we're on our way down to seven thousand." At 1457:33 CST, Denver Center gave the pilot the McCook, Nebraska, weather. The pilot replied, "Okay, let's go to McCook...." Denver Center issued a vector for McCook to the pilot.

At 1459:52 CST, the pilot reported to Denver Center, "...we just lost our McCook navaid." This was the last radio transmission received from the pilot. Denver Center reported losing the airplane's transponder at 1501:20 CST.

Denver Center contacted the Columbus (Nebraska) Automated Flight Service Station (AFSS), at 1502:25 CST, to inform them of the situation. At 1506:41 CST, Columbus AFSS contacted Red Willow Aviation, the fixed base operator (FBO), at the McCook Airport. While talking to Columbus AFSS on the telephone, the FBO reported the airplane flew over the airport at 1512:33 CST. The FBO reported the airplane circled the airport twice with the landing gear up. At 1514:39 CST, the FBO told Columbus AFSS: "He just went down west of the airport in a residential area."

The FBO reported the airplane was circling the airport at approximately 400 feet agl. He stated he could see that the windshield and right hand windows were iced over. When the airplane was between runway 12 and 03, the FBO said: "...he gave it a hard left turn about 40 degrees [angle of bank] and the aircraft pitched nose down from about 200 feet in the air and hit the ground."

Four of the five surviving passengers were interviewed. All four related that the pilot had told them he was having radio problems and wanted to divert to North Platte but the weather was too bad and they were going to McCook. Three of the men recalled being in a left turn circling the airport. They reported feeling the airplane shake after the pilot steepened the turn.

One of the survivors was a former U.S. Navy flight simulator instructor. He was seated in the forward facing seat on the right side of the airplane, and could see part of the instrument panel. He reported both windshields iced over completely during the descent. He could see the vertical speed indicator (VSI), and recalls the descent was at 1,000 feet per minute. He said he looked at the altimeter when the airplane broke out of the clouds and it was indicating 4,000 feet. He reported the pilot asked everyone to help look for the airport. He said they saw the airport through a left side window and circled. He could tell all of the runways were snow covered. He stated the pilot increased bank to 45 degrees, then he felt a buffet and the nose went down, the airplane hit some trees, he felt a tumbling sensation, felt a hard impact then it was silent.

Personnel information

The pilot held a Commercial Pilot Certificate with airplane single and multiengine land, and instrument ratings. He held a Class 1 Medical Certificate with no limitations. The company flight records indicate the pilot had accumulated 2550 hours total flight time, with 66 hours in this make and model airplane.

The records show he had flown 84 hours in the last 90 days, 48 hours in this make and model airplane. The pilot had received a satisfactory FAR Part 135 flight check administered by an FAA Inspector, on January 21, 1994.

Aircraft information

The airplane was a Cessna 421C, serial number 421C-0215, and was manufactured in 1977. Total accumulated airframe time at the time of the accident was 5837 hours. The last inspection was a 100 hour inspection completed on November 29, 1993. The airplane had flown 48 hours since the last inspection.

Examination of the operator's maintenance records did not reveal any outstanding or deferred maintenance items. It was noted that five alternators and one voltage regulator had been replaced during the 18 month period prior to the accident.

The airplane was equipped with a factory installed equipment package which allowed flight in icing conditions as defined by the FAA. The package consisted of wing, empennage, and propeller deice boots; electric windshield for the pilot; heated stall warning vane; heated wing locker tank vents; heated pitot tube