WPR14LA271

The pilot’s execution of a traffic pattern that did not put the airplane in position for a normal final approach and the pilot’s decision to continue the landing attempt instead of initiating a go-around, which resulted in the airplane exceeding its critical angle-of-attack and experiencing an aerodynamic stall at an altitude too low to prevent ground impact.

The owner/pilot was participating in a fly-in to a backcountry airport that he had flown into once about 2 years before. He was the last of his group to arrive in the airport vicinity, and he reported that he was using his GPS, published guidance, and information from fellow pilots to navigate to and enter the airport's traffic pattern. The pilot stated that on the base leg, he determined that the airplane was higher and much closer to the runway than he anticipated. In response, he initiated a left-wing-down slip to lose altitude, and shortly thereafter, while concurrently attempting to maintain the slip, he initiated a left turn to align with the final approach path. Almost immediately after the turn began, the airplane stalled, descended, and impacted trees and terrain about 800 feet short of the runway threshold. Postaccident examination of the airplane revealed no evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation. Although the pilot reported that he extended the flaps to 40 degrees on the downwind leg, the flaps were found extended to 15 degrees. A published arrival procedure suggested a traffic pattern altitude of 800 to 1,000 ft above field elevation (AFE) and a final leg about 1 mile in length. A ridge between the runway and the downwind leg limited pilots' view of the airport while on downwind, and the 1-mile final provided an opportunity to detect airborne or ground traffic sufficiently early to allow pilots to safely compensate for the traffic. Analysis of data from an onboard GPS device revealed that the pilot's traffic pattern differed significantly from the published pattern. His downwind leg began at an altitude of about 800 ft AFE but then descended continuously at a rate of about 400 ft per minute. Also, the pilot made about a 70 degree turn to base leg when the airplane was abeam the threshold. Turning less than 90 degrees resulted in a base leg oriented away from the runway and necessitated a turn of about 110 degrees to align with the final approach course. Further, turning early rather than continuing until the airplane was about 1 mile from the threshold, as suggested, put the airplane on a base leg that was very close to the runway. Despite the descending downwind leg, the airplane's position at the point that the pilot began his turn to final required a steep approach slope (about 10 degrees) to arrive near the threshold in position for a normal landing. When the pilot recognized that the airplane was too high and too close to the runway to use a normal approach slope (about 4 degrees), he could have opted to discontinue the landing attempt and execute a go-around. However, the pilot stated that he continued the approach because he believed that successful completion of the landing was well within his and the airplane's capabilities. The pilot reported that he used approach speeds similar to the airplane's original certificated airspeeds, but the investigation was unable to determine the pilot's actual traffic pattern airspeeds. The investigation was also unable to determine the reason for the difference between the pilot's reported flap setting of 40 degrees and the as-found setting of 15 degrees; it is possible that the pilot began retracting the flaps after the airplane stalled. If the flaps were set to 15 degrees when the pilot believed them to be at 40 degrees, and if he was flying at the lower airspeed appropriate for the greater flap extension, this would have reduced his stall margin. Finally, the pilot's intentional slipping of the airplane while in the turn to final resulted in a steep, uncoordinated turn, which increased the airplane's susceptibility to a cross-control stall. The airplane was extensively modified from its original Federal Aviation Administration (FAA) certificated design by the installation of five significant aerodynamic or performance-related modifications that were approved through the FAA's supplemental type certificate (STC) process. Although this combination of STC modifications was commonly installed on the same airplane, each of the STC modifications was developed by a different company with very limited or no coordination between them. In addition, only two of the STCs were approved by the same FAA office, and there was very limited or no coordination between any of the other FAA offices. Although the STCs were primarily marketed as modifications that would provide short takeoff and landing capability to the airplane, the FAA-approved performance data that was provided with the STCs differed significantly from and did not support some of the advertised performance gains. In addition, in some cases, the STCs' pilot's operating handbook supplements provided conflicting performance data, and there was no guidance provided regarding which performance data was applicable to the final airplane configuration. Further, those STC modifications that were made to the accident airplane were frequently installed together on the same airplane, yet no definitive FAA-approved performance data was available to the pilot to operate the airplane. Further, in this accident, the pilot could also have been motivated to operate the airplane in a manner that capitalized on the advertised performance benefits of the installed STCs.

HISTORY OF FLIGHT On June 29, 2014, about 0810 mountain daylight time, a Cessna 182Q, N132K, was substantially damaged when it impacted trees and terrain while maneuvering in the traffic pattern to land on runway 19 at Big Creek airport (U60), Big Creek, Idaho. The owner/pilot was seriously injured. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no Federal Aviation Administration (FAA) flight plan was filed for the flight. The pilot planned to fly his airplane, in a pre-arranged group of several other airplanes, into U60 to attend a fly-in breakfast event there. The airport was considered a "backcountry" airport, denoting that it is situated in mountainous terrain, and typically requires approach and/or departure procedures that are more demanding and less forgiving than most airports. According to an eyewitness, who was part of the group, and who had already landed, he saw the airplane during the last 20 to 30 degrees of its turn from base to final, after it "came around the Hogback," a ridge parallel to and on the left downwind leg side for runway 19. The witness's impression was that the airplane was "really low and slow" for its position relative to the runway. He estimated that the airplane was at about "one third [of] the height" that an airplane would normally be for the base-to-final turn. However, the witness was not certain about how far out on the final leg the airplane was when it made the turn, and he allowed that it could have been significantly closer to the runway than was normal for that airport. The witness did not see the airplane long enough or well enough to observe its flap configuration. The witness stated that he observed the airplane pitch "immediately nose down and left" as it made the turn. He heard the application of "full [engine] power," and the airplane descended behind the trees. According to the pilot, he had entered the traffic pattern, and was transitioning from the base leg to final when the airplane departed controlled flight, descended rapidly into the trees, and impacted the ground. The airplane came to rest inverted in a ravine forested by tall trees, about 800 ft short of the runway. PERSONNEL INFORMATION FAA records indicated that the pilot held a commercial pilot certificate with airplane single engine land and instrument airplane ratings. According to information provided by the pilot, he had approximately 1,267 total hours of flight experience, including approximately 520 hours in the accident airplane make and model. His most recent flight review was completed in December 2012, and his most recent FAA third-class medical certificate was issued in June 2012. The pilot reported that he had flown into U60 one time previously, about 2 years before the accident flight. According to FAA records, in September 2009, the pilot was attempting to conduct a touch-and-go in the same airplane on a "182 yard" (546 ft) long gravel bar in the Willamette River near Newberg Oregon, which resulted in the airplane becoming "completely submerged" in the river. AIRCRAFT INFORMATION The airplane was manufactured in 1979 as Cessna serial number 18266782, with an original registry of N96609. It was purchased by the pilot in July 2007, and re-registered by him as N132K in February 2008. FAA records indicated that between January and April 2008, the airplane was modified to incorporate numerous major alterations, primarily by means of FAA Supplemental Type Certificates (STCs). An STC is the FAA's approval of a major change in the type design of a previously type certificated product. STCs are primarily issued by FAA Aircraft Certification Offices (ACO).The STC changes incorporated into the accident airplane included, but were not limited to, installation of the following: - Continental IO-550 engine - 3-blade propeller - Canards - Wingtip extensions (37 inch span increase) - Oversized wheels and tires METEOROLOGICAL INFORMATION The 0751 automated weather observation at McCall Municipal Airport (MYL), McCall, Idaho, located about 36 miles southwest of the accident site, included calm winds, visibility 10 miles, clear skies, temperature 8 degrees C, dew point 6 degrees C, and an altimeter setting of 30.08 inches of mercury. AIDS TO NAVIGATION The pilot used his portable GPS device, published guide information, and information from fellow backcountry pilots to navigate to the airport, and in its traffic pattern. The pilot's airplane was the last of a small, pre-coordinated group of airplanes that traveled from MYL to U60. All the other airplanes in the group had already landed when the accident occurred. AIRPORT INFORMATION According to FAA information, U60 was at an elevation of 5,743 ft above mean sea level (msl), and was equipped with a turf runway that measured 3,550 by 110 ft. The runway was designated 1/19. The Idaho Division of Aeronautics (IDA) published a series of "Airport SOPs" (standard operating procedures) for many backcountry airports, including U60. The IDA U60 SOP suggested a left-hand traffic pattern with an altitude of 800 to 1,000 ft above the field elevation (AFE), which result in traffic pattern altitudes between 6,543 to 6,743 ft msl. The SOP also depicted a suggested arrival and traffic pattern ground track, which included an upwind leg offset to the west-northwest of the runway, a downwind leg offset about 1/2 mile from the runway, and a base turn location which resulted in a final leg length of approximately 1 mile. The IDA Pilot and Safety/Education Coordinator stated that the upwind leg was intended to enable the arriving pilots to view the airport and assess its conditions, traffic, and wind. He also noted that because the runway was not normally visible from the downwind leg, due to its obscuration by the Hogback Ridge, which was parallel to and east-southeast of the runway, the 1 mile final was intended to enable pilots to detect airborne or ground traffic sufficiently early to allow them to safely compensate for the traffic. The IDA-prescribed traffic pattern, when flown at a traffic pattern altitude of 1,000 ft AFE, and utilizing a constant descent profile beginning at the point abeam the threshold, would result in a descent slope of about 400 ft per nm, or a descent angle of about 3.7 degrees. Based on that constant slope profile, the turn to base leg would occur at an altitude of about 6,343 ft msl (600 ft AFE), and the turn to final would occur at an altitude of about 6,143 ft msl (400 ft AFE). High terrain in close proximity to the airport could necessitate a slight offset of the final approach track to the east, in order to concurrently maintain the constant descent profile and adequate terrain clearance. WRECKAGE AND IMPACT INFORMATION FAA personnel arrived at the accident site on July 1, 2014; they were the only investigative personnel to examine the airplane on scene. According to FAA inspectors, the airplane came to rest in an inverted position in a heavily wooded area. They estimated the trees to be about 50 ft tall, and observed multiple tree fragments on top of the wreckage. The wreckage was tightly contained, and all major components were accounted for on scene. The airplane was adjacent to a ground scar that was consistent with an engine and propeller impact. The right wing was fracture-separated from airplane at the root, and located just aft and outboard of the left wing, which remained attached to airplane. The aileron crossover/balance cable was the only remaining attachment between the right wing and the airplane. The nose landing gear assembly was found approximately 40 ft forward of the main wreckage area, and both main wheel and tire assemblies were fracture-separated from their respective landing gear struts. The engine cowl flaps were found in the closed position. All engine controls were found in the full