CEN13FA130

The pilot’s inadvertent encounter with severe icing conditions, which resulted in structural icing and the subsequent loss of airplane control.

The pilot filed an instrument flight rules flight plan and, about an hour before departure, he obtained a weather briefing, which included an airmen's meteorological information (AIRMET) for the potential for moderate icing conditions and turbulence below 8,000 ft over the route of flight. About the time the airplane departed, weather conditions worsened with freezing fog, heavy snow fall, and reduced visibility. However, at that time, neither a significant meteorological information (SIGMET) nor a center weather advisory warning of severe icing conditions had been issued. After departure, an air traffic controller cleared the airplane to climb to 9,000 ft mean sea level (msl). When the airplane was about 7,000 ft msl and still climbing, the pilot asked the controller if there were any reports regarding the cloud tops, and the controller responded that there were not. Less than a minute later, radar data showed the airplane descending, and the pilot issued a "mayday" call. Radio and radar contact were then lost. The wreckage was found about 11 miles northeast of the airport. A postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. Flight crewmembers of two flights inbound to the airport around the time of the accident reported that they encountered freezing rain and severe mixed icing; these conditions were beyond the airplane's icing certification standards and could have caused increased weight, degraded performance, and unpredictable aerodynamic characteristics. Federal Aviation Administration guidance warns that, when severe icing conditions are encountered, the pilot shall immediately request priority handling to facilitate a route or an altitude change to exit the icing conditions. Based on the weather information, it is likely that the airplane encountered severe icing conditions about the time of the accident, which resulted in structural icing that exceeded the airplane's capabilities and resulted in a loss of control. Based on the wreckage distribution, which was consistent with a high-speed impact, and the low visibility present at the time of the accident, it is likely that, after the loss of airplane control, the pilot experienced spatial disorientation; however, there was insufficient evidence to determine the role that spatial disorientation might have played in the accident.

HISTORY OF FLIGHT On January 11, 2013, about 1553 central standard time, N36VE, a Raytheon Aircraft Company 58, multi-engine airplane, was destroyed after impacting terrain near Maxwell, Nebraska. The pilot and three passengers were fatally injured. The airplane was registered to and operated by Bottorff Construction, Inc.; Atchison, Kansas. Instrument meteorological conditions (IMC) prevailed at the time of the accident and an instrument flight rules (IFR) flight plan had been filed for the 14 Code of Federal Regulations Part 91 business flight. The airplane departed North Platte Regional Airport (LBF), North Platte, Nebraska, about 1545, and was en route to York Municipal Airport (JYR), York, Nebraska. About 1550 the pilot reported to a radar controller at Denver Air Route Traffic Control Center that he was climbing to a planned cruise altitude of 9,000 feet mean sea level (msl) . At 1552 the pilot requested the tops of the clouds; however, a current report on the cloud tops was not available. At 1553 a "mayday" call was heard and a simultaneous loss of radio and radar contact was reported by the radar controller. At 1855 the wreckage was found in a remote area about 11 miles north east of LBF by emergency responders who had been searching for the missing airplane. PERSONNEL INFORMATION The pilot, age 54, held a Federal Aviation Administration (FAA) private pilot certificate with ratings for airplane single engine and multiengine land, and instrument airplane. His private pilot certificate in airplane single engine land was initially issued on March 9, 1988, his rating in instrument airplane was issued on March 20, 2002, and his rating in airplane multiengine land was issued on February 25, 2003. The pilot also held an FAA third-class medical certificate, issued on August 15, 2012, with a restriction "must have available glasses for near vision". A review of portions of the pilot's three logbooks showed entries beginning on February 17, 1986, with the last entry in pilot's logbook number three on January 1, 2013. Based on only the incomplete entries in pilot's logbook number three, his total pilot experience was estimated at 1,377 hours, with about 457 hours in multi-engine airplanes, and the remainder in single-engine airplanes. His instrument flying experience was estimated at 171 hours. Logbook entries for the previous calendar year showed he had flown about 103 total hours, of which about 80 hours were in the accident airplane. A pilot logbook endorsement on December 6, 2011, showed he had completed an instrument proficiency check and a course in BE 58P Differences, including 4 hours of simulator flight training and 2.5 hours of classroom training. The most recent instruction from a certified flight instructor was on February 20, 2012, showing a flight review was completed in a Beechcraft 58P airplane which included 2.0 hours of flight instruction and 0.5 hours of actual instrument flying. AIRCRAFT INFORMATION The low-wing, retractable conventional landing gear, multi-engine airplane, serial number (s/n) TH-1957, was manufactured in 2000. It was powered by two 285-horsepower Continental Motors, Inc. engines; s/n 1005940 installed on the left side, and s/n 1005978 installed on the right side. Each engine drove a Hartzell model PHC-J3YF-2UF, 3-blade metal alloy full feathering propeller. The airplane was equipped with ice protection systems which included a surface deice system, electrothermal propeller deice, pitot heat, stall warning anti-ice, and heated fuel vents. A postaccident review of original aircraft maintenance documents provided by the operator showed that an annual inspection was completed on May 21, 2012, at an airplane total time and Hobbs meter time of 1,740.9 hours. Entries also noted that both engines were installed on that date and were factory new "zero time" engines. The last aircraft maintenance logbook entry on December 7, 2012, showed that the aircraft total time and Hobbs meter time was then 1,835.0 hours. Fuel records at LBF showed that the pilot had the main fuel tanks "topped off" with a total of 80.0 gallons of 100LL aviation gasoline and the credit card fuel slip was time-stamped at 1443. METEOROLOGICAL INFORMATION At 1534 the Automated Surface Observation System at LBF reported wind from 350 degrees at 14 knots, visibility 4 miles in mist, ceiling overcast at 1,000 feet above ground level (agl), temperature minus 2 degrees Celsius (C), dew point minus 4 degrees C, altimeter 29.42 inches of mercury. Remarks included: ceiling 700 variable 1,300 feet agl. At 1553 LBF reported wind from 340 degrees at 14 knots gusting to 20 knots, visibility 3 miles in light freezing rain and mist, ceiling broken at 900 feet agl, overcast clouds at 1,200 feet, temperature minus 2 degrees Celsius (C), dew point minus 4 degrees C, altimeter 29.45 inches of mercury. Remarks included: freezing rain began at 1546, ceiling 600 variable 1,100 feet agl, pressure rising rapidly, hourly precipitation less than 0.01 inch. The National Weather Service Aviation Weather Centers (AWC) Area Forecast issued at 1425 expected overcast clouds at 5,000 feet mean sea level (msl) with tops to 16,000 feet msl with visibility 3 miles in mist over southern Nebraska. The forecast was amended by AIRMET Sierra for IFR conditions over the region, which forecasted ceilings below 1,000 feet and visibility below 3 miles in precipitation, mist, and blowing snow, over all of Nebraska. AIRMET Zulu was issued at 1445 which called for moderate icing conditions below 17,000 feet msl. The pilot had contacted the FAA contract Automated Flight Service Station (AFSS) several times during the day for each of his flights. On the last call at 1452 the pilot was advised of the AIRMET for icing conditions and turbulence below 8,000 feet, and the pilot made a comment that he was expecting those conditions to be developing over the area. At that time a SIGMET or a Center Weather Advisory warning of severe icing conditions had not been issued. Two helicopter flight crews operating into LBF immediately after the accident reported they had not anticipated the lower than forecast weather conditions and the wintery mix they encountered. The first flight crew was operating a group of U.S. Army Blackhawk helicopters that landed at LBF about a half hour after the accident. They encountered lowering ceilings less than 500 feet with light freezing rain and mist which changed to a combination of freezing rain, ice pellets, and snow with increasing winds. When the next flight of four Blackhawk helicopters landed a short time later they encountered blowing snow with low visibility. Statements from the crew of a U.S. Army King Air indicated they were inbound to LBF and observed a weather cell north and west of the area moving eastward on their airborne weather radar. Upon descending below 11,000 feet they entered the clouds and encountered icing at approximately 9,000 feet. The icing became heavy to severe icing at 5,000 feet. After they received a field condition report of braking action nil on the runway at LBF they executed a missed approach and diverted to an alternate airport. After landing at the alternate airport, the flying pilot commented on a large area of residual ice that remained in an unprotected area on the airplane. A multi-engine instrument rated pilot who was in a duck blind immediately northwest of the airport witnessed the accident airplane on climb-out after takeoff from runway 30. He reported mist conditions and fog that was "freezing to surfaces". He was also indicated that surface conditions deteriorated shortly afterward with visibility as low as a quarter mile when it began to "snow hard". COMMUNICATIONS AND RADAR At 1448:32 the pilot of N36VE called the Fort Worth Federal Contract Flight Service Station (FCFSS) via telephone to file two IFR flight plans. He obtained an abbreviated pilot weath