CEN10MA088

A loss of control for undetermined reasons.

The flight was scheduled to pick up cargo at the destination airport and then deliver it to another location. During the descent and 14 minutes before the accident, the airplane encountered a layer of moderate rime ice. The captain, who was the pilot flying, and the first officer, who was the monitoring pilot, made multiple statements which were consistent with their awareness and presence of airframe icing. After obtaining visual flight rules conditions, the flight crew canceled the instrument flight rules clearance and continued with a right, circling approach to the runway. While turning into the base leg of the traffic pattern, and 45 seconds prior to the accident, the captain called for full flaps and the engine power levers were adjusted several times between 50 and 95 percent. In addition, the captain inquired about the autopilot and fuel balance. In response, the first officer stated that he did not think that the spoilerons were working. Shortly thereafter, the first officer gave the command to add full engine power and the airplane impacted terrain. There was no evidence of flight crew impairment or fatigue in the final 30 minutes of the flight. The cockpit voice recorder showed multiple instances during the flight in which the airplane was below 10,000 feet mean sea level that the crew was engaged in discussions that were not consistent with a sterile cockpit environment, for example a lengthy discussion about Class B airspeeds, which may have led to a relaxed and casual cockpit atmosphere. In addition, the flight crew appears to have conducted checklists in a generally informal manner. As the flight was conducted by a Part 135 operator, it would be expected that both pilots were versed with the importance of sterile cockpit rules and the importance of adhering to procedures, including demonstrating checklist discipline. For approximately the last 24 seconds of flight, both pilots were likely focusing their attention on activities to identify and understand the reason for the airplane's roll handling difficulties, as noted by the captain's comment related to the fuel balance. These events, culminating in the first officer's urgent command to add full power, suggested that neither pilot detected the airplane's decaying energy state before it reached a critical level for the conditions it encountered. Light bulb filament examination revealed that aileron augmentation system and stall warning lights illuminated in the cockpit. No mechanical anomalies were found to substantiate a failure in the aileron augmentation system. No additional mechanical or system anomalies were noted with the airplane. A performance study, limited by available data, could not confirm the airplane's movements relative to an aileron augmentation system or spoileron problem. The level of airframe icing and its possible effect on the airplane at the time of the accident could not be determined.

HISTORY OF FLIGHT On January 5, 2010, at 1327 central standard time, a Gates Learjet Corp. 35A, N720RA, operated as Royal Air Freight flight 988 (RAX 988), was destroyed when it impacted water and terrain while maneuvering to final approach to runway 34 at Chicago Executive Airport (PWK), Prospect Heights, Illinois. The captain and first officer sustained fatal injuries. The airplane was owned and operated by Royal Air Freight, Inc., Waterford, Michigan. Visual meteorological conditions prevailed at the time of the accident and an instrument flight rules flight plan was filed for the 14 Code of Federal Regulations Part 91 positioning flight. The flight departed Oakland County International Airport (PTK), Pontiac, Michigan, at 1235. According to the operator, the accident flight was scheduled to pick up cargo at PWK and then transport the cargo to Georgia. The accident flight was the first flight for the flight crew that day. The flight crew reported for duty about 1200. The airplane departed PTK at 1235, en route to PWK. During the takeoff, climb, and en route portions of the flight, no abnormalities were reported by the crew to air traffic control (ATC) nor were any recorded by the cockpit voice recorder (CVR). Review of the CVR transcript revealed that the recording began at 1300:03 while the airplane was en route. At 1306:28, the first officer reported to Chicago air route traffic control center (ARTCC) that their altitude was at flight level two zero zero (20,000 feet mean sea level). The controller then instructed the flight crew to be at 4,000 feet, 35 miles northeast of the Northbrook VOR. At 1308:05, the crew obtained the current automatic terminal information service (ATIS) weather information Quebec for PWK. At 1311:00, the captain stated that he had all the airplane anti-ice systems activated, and a discussion took place involving captain's previous experience flying over the "lake." At 1312:34, the captain stated that the "cabin sucks." Digital electronic engine control (DEEC) data indicated that the engines' low pressure spool speed (N1) was approximately 30 to 50 percent from 1312:18 to 1314:18. At 1314:02, the center controller cleared the flight crew direct to the Northbrook VOR and the first officer acknowledged the clearance. At 1314:25, the captain stated, "yeah, there's ice out there." Seven seconds later, the controller cleared the flight crew to descend and maintain 3,000 feet and contact Chicago approach control, and the first officer acknowledged the clearance. At 1314:58, the first officer stated, "there's ice(ing)," and the captain replied he was glad he had all the airplane anti-ice activated before the descent. The captain stated they were picking up moderate rime ice and the first officer reported the ice conditions to the Chicago approach controller. At 1316:23, the first officer stated, "(look at the) (expletive) tips." Approximately 50 seconds later, the approach controller cleared the flight crew to 2,000 feet and at 1317:37 the first officer reported they broke out of the clouds at 2,600 feet. At 1318:38, the captain stated that he was turning off the anti-ice system and the first officer stated, "don't need it anymore." Between 1311 and 1318 (the time anti-ice system ON as per CVR comments), engine N1 speeds fluctuated between 30 and 80 percent. For approximately the next two and half minutes, the flight crew had a discussion related to airspeeds within the Class B airspace. At 1321:06, the captain stated, "we'll go like one twenty eight on the speed." At 1323:03, the approach controller reported PWK was at their 10 o'clock position and 12 miles, and the first officer reported the airport was in sight. The controller then cleared the flight crew for a visual approach to runway 16 and to contact the PWK air traffic controller tower (ATCT). After contacting ATCT, the flight crew was cleared for a right traffic circling approach to runway 34, and they canceled instrument flight rules (IFR). At 1324:18, the captain called for flaps at 8 degrees and turned the yaw damper off at 1325:02. The flight crew discussed the winds were reported at 310 degrees at 9 knots. At 1325:49, the flight crew was cleared to land and the first officer acknowledged the transmission. Four seconds later, the captain called for the landing gear to be extended. The crew then briefed portions of the before landing checklist and at 1326:27, the captain called for flaps at 20 degrees. At 1327:02, the captain called for full flaps (40 degrees) and the first officer responded, "plus twenty." Post-accident performance studies indicated that the airplane's bank angle increased, and the true airspeed decreased. At 1327:10, one of the two crew members stated, "what the # going on up here." The captain stated, "that was # weird." At 1327:18, the first officer stated, "advance the power," and the sound of laughter followed. Post-accident performance studies indicated that the airplane's true airspeed and N1 increased. At 1327:21, the captain inquired whether the autopilot was off and nine seconds later, one of the crew members stated, "I don't like this at all...what the # is going on." At 1327:34, the captain asked the first officer to check the balance on the fuel, and the first officer responded, "looks good. I don't think that spoileron thing is working for some reason." Post-accident performance studies indicated that the airplane's N1 and true airspeed decreased, and bank angle increased to greater than 50 degrees. The sound of 2 "clicks" was then heard at 1327:41.8 and 1327:42.5, respectively. At 1327:42.7, the first officer stated, "add full power, add full power." The CVR recording ended at 1327:48.5. A witness, who was located at the PWK airport, observed the airplane on a right base leg to runway 34. The witness reported the airplane started to turn to final approach and the bank angle "got very steep, very fast [sic] until the aircraft which seemed to snap roll into a stall and then immediately into a nose dive..." Another witness (a pilot familiar with PWK) who was riding in a vehicle, reported he first observed the airplane on a right downwind for runway 34. He reported, "The aircraft appeared to make a normal downwind to base turn. However, on the base to final turn, the airplane seemed to be slightly uncoordinated with the right wing down, slightly nose low, and the empennage skidding outside of the turn." He then lost sight of the airplane behind buildings and trees. PERSONNEL INFORMATION The director of operations (DO) for Royal Air Freight provided personnel records, training records, and duty and flight time records for the captain and first officer. The information in this section was extracted from that data and Federal Aviation Administration (FAA) records. Captain The captain held an airline transport pilot certificate with an airplane multiengine land rating, and type ratings for Learjets and the Cessna Citation 500 series airplanes. The certificate listed commercial pilot privileges for single engine land airplanes. He was hired by the operator in September of 2003 as second in command (SIC) in Learjet airplanes. In June of 2005, he received transition training to act as pilot-in-command (PIC) in EMB-110 airplanes. On July 2, 2009, he completed Part 135 proficiency and line checks to act as PIC in Learjet airplanes. The captain held a first class airman medical certificate dated April 21, 2009, with no restrictions. On his most recent medical certificate application, the captain listed 7,100 flight hours with 300 hours accumulated within the previous 6 months. Information provided by the operator indicated that the captain had accumulated about 3,000 hours in Learjet airplanes, including 400 hours as PIC. The captain's pilot logbook was not available for review. According to FAA and operator records, the captain had accumulated the following flight time prior to the acc