The pilot of a Pilatus PC-12 (N56KJ) and eight of his passengers lost their lives and three other passengers were seriously injured when he lost control of the airplane immediately after takeoff on Nov. 30, 2019. The FAR Part 91 personal flight was departing Chamberlain Municipal Airport (K9V9) in Chamberlain, South Dakota. The skies were overcast, snow was falling, and there was a fresh layer of snow on the ramp and the runway at the time.

Given the wintry conditions, icing was an obvious explanation for the crash. After a lengthy investigation, however, it turned out that other factors were responsible for the accident. A lightweight data recorder (LDR) was a key part of understanding why.

On the day before the accident, the pilot and his passengers flew into Chamberlain, arriving at about 0927 CST. A representative from a nearby pheasant hunting location, Thunderstik Lodge, picked them up and drove them to the lodge, where they stayed overnight. The airplane remained parked on the ramp, and during the night, snow fell.

On Saturday morning, the day of the accident, the pilot and one of the passengers rode to the airport with the lodge manager while the other passengers were hunting. The pilot brought a 7-ft. ladder from the lodge, and he stopped at a local hardware store to buy isopropyl alcohol for deicing. According to the lodge manager, the pilot and passenger worked for 3 hr. attempting to remove the snow and ice on the airplane. The ladder wasn’t high enough for them to deice the top of the empennage.

The lodge manager told the pilot they had room for their group to stay another night, but the pilot said they needed to get home. The manager later said snow was falling hard when the airplane departed.

The passengers arrived and began to board shortly after noon. The LDR began to record their remarks, the pilot’s remarks and the ambient sounds on board the airplane beginning at 1215.

Someone asked, “How much ice was there this morning?” Another person replied, “Oh, there was a lot.” There was no answer to a question about how well the ice had come off. One person is heard reciting a prayer and another commenting on being able to “get a lot of pheasants in only an hour.”

The pilot started the engines at 1219 and tuned in the Chamberlain automated weather observing system (AWOS) broadcast. It was “Chamberlain Municipal Airport automated weather observation one eight two zero zulu. Weather: wind, zero one zero at seven; visibility, three-quarters light snow; ceiling, five hundred overcast; temperature, one Celsius; dew point, one; altimeter, two niner three zero. Increased waterfowl and bird activity near the runway.”

At 1224, the pilot contacted Minneapolis Center on his cellphone and put his IFR clearance on request. Three minutes later, ATC cleared N56KJ to Idaho Falls Regional Airport (KIDA) via direct, to climb and maintain 8,000 ft., with a departure frequency of 125.1. The clearance was void if not off by 1235. After the pilot’s read-back, Minneapolis told him they had received reports of light to moderate mixed icing throughout the day.

While the pilot was getting his clearance, the airport manager was attempting to contact him on the local Unicom frequency. When the pilot announced he was about to taxi, the manager said, “It don’t look good to me. I don’t know what you guys are thinkin’.”

Asked if the runway was in good condition, the manager said, “I would say I can’t hardly keep up.” When the pilot decided to taxi anyway, the manager said, “The runway is not clear,” and “You guys are crazy...I got berms on this thing--I gotta get the snow outta here.”

The pilot replied, “I think we’re gonna be just fine right down this uh one track you’ve made six kilo juliet.” The airport manager said, “[if you] guys don’t mind some drifts.”

Speaking to the right-seat passenger, the pilot said, “This thing will take off so fast,” and “I need most of the runway, but I’ll be good.”

The pilot turned around at the end of the runway and commenced his takeoff at 1231:58. The airplane lifted off in 30 sec., and one second later, an automated voice warning began to announce, “stall, stall, stall.” The airplane rolled left, reaching a left bank of 64 deg. and a maximum altitude of 380 ft. above the ground before it began to descend. The airspeed got as high as 97 kt. but decayed to 80 kt. at its peak altitude and bank.

A nearby witness reported that the engine sounded like it was “running good” although he could not see the airplane due to limited visibility.

The sound of impact came at 1233. Only 62 sec. had elapsed since the beginning of the takeoff roll.

The Investigation

The NTSB conducted a field major investigation that was eventually classified as a limited Class 3 investigation. In addition to the FAA, the Swiss Transportation Board and Pilatus participated in the investigation. The final report was not published until May 19, 2022, almost 2.5 years after the accident.

The wreckage was located 0.75 mi. west of Chamberlain Airport. The debris path was 85 ft. long along a southerly heading. The left wing and engine were separated from the main wreckage, which consisted of the fuselage, right wing and empennage. The flaps were set to 15 deg. and the landing gear was retracted. Trim was in the takeoff range. Recorded engine data showed the engine was operating normally.

Chamberlain Airport is a public, uncontrolled airport with continuous attendance. Runway 31 is asphalt-paved in fair condition, 4,299 ft. in length and 75 ft. in width. The airport elevation is 1,696 ft. ASL and the nearby terrain is level.

Chamberlain is on the east bank of the Missouri River where Interstate 90 crosses it, and it is 112 nm west of Sioux Falls.
N56KJ was manufactured in 2013 and was not required to be equipped with a flight data recorder (FDR) or cockpit voice recorder (CVR). However, the airplane did have an L3Harris lightweight data recorder. The LDR was found to be in good condition, and it recorded both flight data and voice data. NTSB staff were able to download both sets of data.

The FDR specialist was able to construct a map overlay of the airplane’s flight path on Google Earth. He was also able to verify that the anti-ice and deice equipment, including pitot heat, prop heat, static heat, windshield heat and angle of attack (AOA) heat, were on. The left pitot heat went off before the airplane taxied, but flight parameters were unaffected.

The LDR recorded two voice channels, one for the pilot and front seat passenger and one for the cockpit area microphone. The duration of the voice recording was 18 min., 37 sec. and the quality of both channels was excellent. A CVR group consisting of investigators from the NTSB, the FAA and Pilatus was formed to audition the recording and transcribe all remarks and sounds heard.

No weight and balance document was found, but the investigator in charge (IIC) reconstructed one. He obtained passenger weights from the funeral home and survivors, determined passenger locations by talking with survivors, estimated the ramp and takeoff fuel weights, and used the weight of recovered baggage to make his estimate. He found the airplane weighed 10,557 lb. at takeoff, 107 lb. above the maximum allowable, and the center of gravity (CG) was well aft of the aft limit.

There were 10 seats on the airplane, but there were 12 persons on board. Based on their weights, two of the passengers were children, and they were seated in the aisle. If they were seated in the forward part of the aisle, the CG was only 3.99 in. aft of the aft limit. If they were seated in the rear part of the aisle, the CG was 5.49 in. aft of the aft limit.

A person at the airport took pictures and videos of the airplane on the ramp, during taxi and during takeoff. Using the photo taken of the airplane as it taxied out, Pilatus determined that the airplane was very tail heavy. The photos also showed that some snow remained on the vertical and horizontal stabilizers.

In Part 2, we’ll discuss the performance evaluation of the accident aircraft and the NTSB’s conclusions.