Final Report: OSU King Air crash

 - August 12, 2008, 5:06 AM

BEECH King Air 200, Strasburg, Colo., Jan. 27, 2001–The NTSB determined the probable cause to be the pilot’s spatial disorientation resulting from his failure to maintain positive manual control of the airplane with the available flight instrumentation. Contributing to the cause of the accident was the loss of aircraft electrical power during IMC.

At about 5:37 p.m. MST King Air N81PF crashed into rolling terrain near Strasburg while on an IFR flight plan in IMC. The aircraft, which was being operated under FAR Part 91, was owned by North Bay Charter and operated by Jet Express Services.

N81PF was one of three airplanes transporting members of the Oklahoma State University (OSU) basketball team and associated team personnel to Stillwater Regional Airport (SWO), Okla., after a game at the University of Colorado at Boulder that afternoon. All 10 occupants aboard N81PF were killed and the aircraft was destroyed.

The flight departed about 5:18 p.m. from Jefferson County Airport (BJC), Broomfield, Colo., with two pilots and eight passengers. The pilot who occupied the left seat in the cockpit was solely responsible for the flight, according to the FARs. The pilot who occupied the right seat in the cockpit, referred to as the “second pilot,” was not a required flight crewmember as the aircraft and operation were certified for single-pilot operation.

On the day before the accident, the pilots departed Wiley Post Airport (PWA), near Oklahoma City, Okla., for a positioning flight to SWO. It was there that members of the OSU basketball team and associated personnel boarded the airplane, which then continued to BJC.

According to ATC records, N81PF made its first radio contact with Kansas City Center at about 3:49 p.m. CST. Its last radio contact with the Denver Tracon occurred at about 4:52 p.m. MST. Records from Stevens Aviation, an FBO at BJC, indicated that the airplane landed at 5 p.m. and was placed in a hangar overnight.

ATC records indicated that the pilot contacted the Denver Automated Flight Service Station at about 11 a.m. on the day of the accident to obtain a weather briefing and file IFR flight plans for the return trips to SWO and PWA. The weather briefing included a general synopsis of the weather for the proposed flights, airmet flight advisories for occasional moderate icing and occasional moderate turbulence, forecast airport conditions, winds and temperatures aloft and notices to airmen in effect.

A Stevens Aviation ramp worker at BJC said the airplane was towed from the hangar at between 11:15 and 11:30 a.m. on the day of the accident. The ramp worker also stated that the pilots arrived at the airport sometime after 1 p.m. and requested the airplane be returned to a hangar until after the passengers boarded. According to the ramp worker, the airplane was subsequently returned to another hangar. The pilots left the airport to attend at least the first half of the basketball game, which began at 2 p.m.

According to ATC records, the pilot contacted BJC ground control at about 4:30 p.m. to obtain an IFR clearance to SWO, and it was issued as filed. The Stevens Aviation ramp worker indicated that the passengers arrived at 5 p.m. and boarded the aircraft before it was towed from the hangar. At 5:12 p.m. the pilot contacted ground control to request taxi instructions, indicating that he had received ATIS information Quebec. Because ATIS information Romeo was current at the time, the ground controller issued the new weather information along with the taxi clearance to Runway 29R.

At 5:17 p.m. the pilot reported that the airplane was ready to depart from Runway 29R. The ground controller instructed the pilot to hold short of the runway for an IFR release, which was issued a few seconds later. The pilot was then cleared for takeoff and instructed to turn right to a 40-degree heading. At 5:19 p.m. the local controller instructed the pilot to contact Denver Tracon. He complied and reported to Denver that he was climbing through 6,500 feet for 8,000 feet. This was followed by the departure controller’s issuing a clearance to 12,000 feet and instructions to fly the airplane on a 60-degree heading. At 5:22 p.m. the controller instructed the pilot to proceed to the epkee intersection, join the Garden City transition and climb to 23,000 feet. The pilot acknowledged.

At 5:24 p.m. the departure controller instructed the pilot to fly the airplane on a 110-degree heading, and again the pilot acknowledged the instruction. About a minute later the controller instructed the pilot to contact the Satellite Radar Two controller. He did at 5:26 p.m., reporting he was at 16,300 feet and climbing to 23,000 feet. The controller asked the pilot whether he was flying directly to the epkee intersection and the pilot responded that he had been proceeding to the intersection but had been assigned a heading of 110 degrees. The controller then cleared the airplane to proceed directly to the epkee intersection and the pilot responded he was going directly to the intersection and that he needed to make about a three-degree left turn. There were no further transmissions from the aircraft.

Mode-C information from the airplane’s transponder indicated that the King Air reached its cruising altitude of 23,000 feet at about 5:32 p.m. According to ATC radar data, the airplane’s climb to this altitude was normal, and its airspeeds had been steady. The last mode-C transponder return occurred at about 5:35 p.m., when the airplane was at an altitude of 23,200 feet. Radar data indicated that the airplane started to deviate from its heading and turn to the right about 42 seconds after mode-C information was lost. Mode-A information from the transponder remained available until about 5:37 p.m. and within about five to eight seconds after loss of mode-A information the airplane hit rolling terrain at an elevation of 5,223 feet.

The NTSB investigation found that the pilot was properly certified and qualified, with no evidence of a pre-existing medical or behavioral condition that might adversely affect his performance. The second pilot was properly certified and qualified, though he was not a required flight crewmember. N81PF was certified for single-pilot operation under both Part 91 and 135 because a three-axis autopilot was installed and operating. Because the flight was conducted with two qualified pilots and an operational autopilot and thus exceeded Part 135 requirements, the NTSB found that the circumstances of the accident would not have been any different if the pilot had operated the flight under Part 135 rather than Part 91.

The aircraft was properly certified, equipped and maintained within the FARs. The recovered components showed no evidence of any pre-existing structural, engine or system failures and there was no evidence of a cabin-pressurization problem. Icing was also ruled out as a factor.

The physical evidence recovered from the wreckage site and the recorded radar data indicate that a complete loss of aircraft electrical power occurred, but the pilot would have had salient cues to identify the failure. As a result, the NTSB determined that the pilot did not appropriately manage the workload associated with troubleshooting the power failure with the need to establish and maintain positive control of the airplane. The airplane’s estimated flight path in the final two minutes of flight was consistent with a graveyard spiral resulting from pilot spatial disorientation.

Furthermore, the NTSB determined that the airplane’s angle at the time of impact indicated that the pilot attempted to arrest the descent in the final portion of the flight, possibly in response to obtaining visual references of the ground after emerging from the lowest cloud layer. But an in-flight breakup occurred because the aerodynamic loading during the pilot’s pull-up maneuver was great enough to overload the horizontal stabilizer downward, and the right outboard wing section was sufficiently loaded upward to sustain a permanent bend in the spar.

The NTSB noted that while the electrical failure was a contributing factor to the accident, it was not considered a causal factor because non-electrical-powered instrumentation remained available that would allow the pilot to fly and land the airplane safely. The NTSB also noted that Oklahoma State University did not provide any significant oversight for the accident flight.