LEBEC, CA, USA
N9615G
Christen Industries A-1
In furtherance of the U.S. Department of Agriculture's Animal Plant Health Inspection Service (APHIS) Wildlife Services aviation program, the rear seat instructor-gunner and the front seat trainee-pilot commenced aerial hunting operations which required the trainee-pilot to maneuver at slow airspeed and low altitude while the instructor-gunner shot coyotes. The instructor was also required to be observant of the recently hired trainee's flying skill and provide any needed instruction. On previous flights, the instructor had observed the trainee experiencing difficulty maintaining altitude during turns. He also opined that the trainee was not strong enough to fully extend the wing flaps. The trainee used two seat cushions behind her back to reposition her closer to the flight controls (and the instrument panel). The instructor did not report his observations to management. During the accident flight following a coyote shoot, the trainee entered a low altitude, slow airspeed, medium bank turn to reverse course. During the turn, the instructor's attention was diverted to search the cabin floor for an ejected live shotgun shell. The instructor looked outside the airplane just as the left wing impacted the level terrain in a nose low attitude. The USDA operated the public-use airplane and directed the instructor to have it maintained by contract mechanics in accordance with FAA regulations. Contrary to the airplane manufacturer's FAA type certificate, the USDA had erroneously connected the front seat shoulder harness, with its associated inertial reel, to the back of the front seat instead of using the prescribed factory mandated location at an overhead airframe hardpoint. Additionally, the shoulder harness webbing was routed beneath seatback material. An engineering analysis revealed that due to the anchoring of the harness to the seat structure rather than the prescribed airframe hardpoint, and the nose low ground impact trajectory, the inertial crash loads to the seat increased thus exceeding its designed strength. The improper harness attachment combined with the compressive fuselage buckling resulted in the seat yielding in a forward bending direction. The trainee's head impacted the instrument panel resulting in fatal injuries. The airplane had undergone four 100-hour and an annual inspection with the harness incorrectly attached.
HISTORY OF FLIGHT On March 11, 1998, at 1009 hours Pacific standard time, a Christen A-1, N9615G, operated by the United States Department of Agriculture (USDA) as a public-use aircraft, collided with terrain approximately 8 statute miles north of Lebec, California. At the time of the accident, the front seat pilot was maneuvering the airplane at a low altitude in furtherance of the USDA's Animal Plant Health Inspection Service (APHIS) Wildlife Services program. Visual meteorological conditions prevailed, and a company flight plan was filed. The airplane was destroyed, and the commercial pilot in the front seat (a trainee in the program) was fatally injured. The rear seat crewmember, who also possessed a commercial pilot certificate, was performing aerial gunnery and instructional duties. He was seriously injured. The local area flight originated from an open field about 0930. The field was located about 5 miles from the crash site, northwest of Interstate Highway 5 and the Pump Plant Road. The USDA management reported that the mission of the APHIS program is to curtail damage to agricultural products caused by wildlife. To effectively accomplish the program's objectives, the Wildlife Services aviation program requires its pilots to fly in close proximity to the ground while maneuvering at slow airspeeds. The accident occurred during an authorized aerial hunting flight operation over a designated work site on private property. The flight crew consisted of a trainee-pilot and an instructor-gunner. An USDA employee-witness, who was working as a ground crewmember in the coyote hunting operation, and the instructor-gunner reported the sequence of events leading to the accident. In summary, the ground-based witness, who was approximately 1/3-mile from the accident site, reported seeing the airplane flying at its customary low altitude. About 30 seconds prior to the crash the witness informed the airplane's crew via radio that he intended to reposition himself closer to the area where the airplane was flying. The instructor-gunner acknowledged his radio transmission and did not indicate any difficulty with the airplane. The witness further reported observing the airplane commence a gradual left, course-reversal turn, and nothing unusual was noted. After about 8 seconds the airplane commenced another left turn. The left wing lowered and a 30- to 45-degree angle of bank was established. Within a second after initiating the left turn, the airplane appeared to be flying more slowly and at a lower altitude than normal, and this alarmed the witness. As the turn progressed, the left bank angle slightly increased and the airplane impacted the ground. The instructor-gunner made several verbal and written statements regarding the sequence of events leading to the crash. In pertinent part, he reported the following: During the accident flight his primary function was to kill coyotes. Secondarily, he was supposed to be observant of the manner in which the front seat trainee-pilot was handling the airplane's controls and provide any needed guidance. The instructor verbally reported that during an earlier low-level turn, the trainee-pilot had allowed the airplane's nose to abruptly lower (as the angle of attack decreased) and the airplane dove toward the ground. The instructor stated that he had informed the trainee that her handling of the airplane was improper, and he provided guidance to resolve the problem. The instructor further reported that a few minutes prior to the crash he shot a coyote. After the shoot, the pilot began reversing course to overfly the general area. The pilot climbed approximately 100 feet above ground level (agl), and then, while looking for additional animals, descended to between 50 and 60 feet agl. Thereafter, the pilot descended to about 20 to 25 feet agl. The instructor ejected a live shell from the shotgun. The shell landed on the airplane's floor rather than in the shell pouch on the rear of the pilot's seat. (The USDA reported that its policy requires that before a firearm is returned inside the airplane, the firearm's breach must be cleared of any live ammunition. This process requires the gunner to briefly redirect his attention from outside to inside the airplane.) The instructor indicated that he redirected his attention from outside the airplane toward the airplane's floor to look for the shell. During this time, the instructor reported that he felt the airplane turn left, the engine power remained around 2,000 or 2,200 rpm, and the stall warning horn activated. The bank angle was more than 30 or 40 degrees, perhaps as much as 65 degrees. The instructor looked up from the floor as the airplane's nose lowered. He attempted to grab his control stick; however, the airplane crashed. The instructor also reported that the pilot "never let on that anything was wrong or she was having a problem of any kind. The aircraft was running good and we had no problems with the controls to my knowledge." PERSONNEL INFORMATION Front Seat Trainee-Pilot. The trainee-pilot weighed 104 pounds and was 61 inches tall. She used two personal seat cushions while flying. The cushions were placed behind the pilot's back to move her forward in the seat. The estimated thickness of her cushions was 4 inches. USDA management reported that because the airplane was manufactured with a fixed (nonmovable) seat, some of its pilots utilize supplementary cushions to move them forward enough to reach the rudder pedals. A review of the pilot's personal flight record logbooks revealed that her total logged flight time was about 4,082 hours. She possessed a certified flight instructor (gold seal) certificate and had given about 1,597 hours of dual flight instruction. The pilot's first experience flying a Christen A-1 occurred on January 20, 1998. The flight was performed with the instructor-gunner in the accident airplane. The purpose of the flight was to receive initial orientation and familiarization in flight operations associated with aerial hunting. Between January and March, 1998, the pilot logged a total of 66.9 hours in the airplane during training flights on 19 days. USDA management reported that along with data submitted by the pilot in her employment application, she indicated having 500 hours of low-level type flying experience. The pilot reported that this experience was gained during contract flying for the U.S. Forest Service and search and rescue missions for the Civil Air Patrol. During the Safety Board's logbook review, no evidence was found of the pilot having any previous low-level flight and maneuvering experience similar to that provided by the USDA in aerial hunting operations. Rear-Seat Instructor-Gunner. The instructor-gunner weighs 144 pounds, and he is 71 inches tall. He does not use extra seat cushions while flying. The instructor-gunner reported that his total flight time was about 6,837 hours, of which about 700 hours were flown in the accident model of airplane. He had flown about 128 hours during the preceding 90-day period. Flight Training. According to the instructor-gunner, when he began teaching the pilot, he placed airplane-handling restrictions on her, which were the same as for any pilot he trains. The restrictions were: (1) No turns or passes at less than 60 miles per hour; and (2) No turns using over a 45-degree angle of bank. The instructor reported that management asked him to provide the new hire with initial indoctrination including flight training appropriate to the USDA's aerial hunting program, and on January 20, 1998, the training commenced. The instructor reported to the Safety Board that the new hire ". . . did a very good job of handling the airplane." But, "she was not strong enough to pull full flaps . . .". Thereafter, the trainee acquired about 43.3 hours of flight training with another USDA instructor who was located in Oregon. This instructor did not report observing any problems with the trainee's airplane handling skills. The trainee then returned to California for additional training with her first instructor. The instructor reported that during a March 9, 1998, flight the trainee had difficulty maintaining the proper pitch attitude after applying full engine power following a shooting pass. As engine power increased, the airplane's nose rapidly pitched upwards. The instructor indicated that the trainee ". . . just was not strong enough to push the nose over, so I told [her] to try [using] trim." During the flight, the instructor also observed that when the trainee banked the airplane toward a coyote she would reduce engine power thus allowing the nose to "drop fast." The instructor stated that he provided the trainee with additional flight instruction. The instructor further reported that during a March 10, 1998, flight, the trainee had ". . . some problems pushing the nose of the airplane forward before a turn after applying full power." He provided her with instruction that seemed to be useful. Also, the instructor stated that he "was concerned" about the trainee trying "to cut [engine] power to idle [during a] turn with a nose low attitude and in a steep dive." The instructor provided about 45 minutes of flight instruction, and opined that the trainee was doing "a very good job." USDA Management Policy. The USDA's regional aviation manager reported that during the accident flight the front seat pilot was receiving instruction in low-level aerial hunting techniques during a 6-month-long flying course. The manager reported that performance of low altitude maneuvers, including maintaining altitude while executing left turns, is a required flying skill necessitated by the aerial hunting operation. The maximum angle of bank generally required during turns is 35 to 40 degrees, and bank angles exceeding this amount are permitted only by experienced pilots. The manager additionally indicated that it is not the USDA's intention to hire pilots with deficient flying skills. When hired, all of the pilots meet the USDA's minimum professional pilot series experience standards. The USDA aviation program does, however, teach the new hires how to perform the unique type of flying, such as low altitude maneuvering, which is required during the aerial hunting operations. Neither the regional nor the State of California program manager reported awareness of any flying skill deficiency on the part of the front seat pilot. Both managers reported that the USDA does not maintain specific written records regarding newly hired pilots' flying skill or flight training progress. However, instructors do provide management with verbal progress reports. Management indicated receipt of at least one verbal report which indicated that the trainee-pilot was satisfactorily progressing. Management indicated it was unaware the trainee was, at times, having difficulty performing specific low altitude turning maneuvers or fully extending the wing flaps. AIRCRAFT INFORMATION According to the USDA, it frequently refers to the Christen A-1 airplane as being a "Husky." The USDA management stated that it had exclusive use of the airplane that it operated and was responsible for its maintenance. The USDA intended that the airplane be maintained in accordance with the Federal Aviation Administration's (FAA) annual and 100-hour inspection requirements. The USDA management reported that its employees were responsible for scheduling all airplane maintenance and ensuring its adequacy. The Safety Board's review of the airplane's maintenance records revealed that between February and March, 1997, the airplane had been modified to accommodate the USDA's mission. In part, the modifications consisted of installation of an automatic flagger device, an openable left side window and communication radios. Thereafter, the airplane was placed into service. As the airplane accumulated flight time it received a series of inspections. By the accident date, the airplane had received four, 100-hour inspections, and one annual inspection. Two different non-USDA (contract) mechanics signed the airplane's logbooks certifying their work during these inspections. The last inspection was performed on March 5, 1998, at 724.57 total airframe hours. Postcrash, the airplane's tachometer registered 741.26 hours. No written evidence was observed in the maintenance records indicating the airplane had any outstanding squawks or received any maintenance since its last inspection. During interviews with the operator, the Safety Board received information that during March 1997, its personnel had performed additional maintenance for which there was no written record. The operator had attached the front seat's shoulder harness, along with its associated inertial reel, to the lower back structure of the front seat. The harness webbing had been routed upward from the inertial reel, beneath seatback material, and over the top of the seat. No evidence of any approvals was found for this shoulder harness attachment installation which varied from the airplane manufacturer's design. According to the airplane manufacturer, at the factory the front seat shoulder harnesses was anchored to an overhead structural hardpoint location on the airframe. The manufacturer reported that the operator's modification never would have been approved. The manufacturer indicated that the shoulder harness attachment at the back of the front seat was contrary to the FAA Type Data, A22NM, for a Husky A-1 airplane. Therefore, at the time of the accident the airplane was not in conformity with its type certificate. METEOROLOGICAL INFORMATION Several persons located in the vicinity of the accident site reported that at the time of the crash it was sunny and the visibility was at least 10 miles. The wind was nearly calm, and the temperature was between 75 and 80 degrees Fahrenheit. COMMUNICATION Neither the USDA nor the FAA reported recording any communications to or from the accident airplane. Also, communications between the airborne crewmembers were not recorded. WRECKAGE AND IMPACT INFORMATION The accident site was located on private property approximately 34 degrees 57.18 minutes north latitude, by 118 degrees 55.45 minutes west longitude. The estimated elevation was 1,500 feet mean sea level. From an examination of the accident site, airplane wreckage, and witness statements, the airplane was found to have descended into the hard dirt surface of an open field while in a left bank and nose down pitch attitude. The initial point of impact (IPI) was noted by the presence of an estimated 1-inch-deep depression in the ground which approximately matched the size and shape of the left wing's leading edge. Red colored left wing navigation light lens fragments and the associated wing's crushed navigation light housing were found at the extreme south end of the ground scar. The airplane's separated pitot tube was found several yards to the north The main impact crater was found about 26 feet north of the navigation light. The crater was oval shaped, about 1-foot deep, and was the approximate size of the airplane's engine compartment. The entire airplane structure, which remained principally intact, was found about 15 feet northeast of the main crater. The left wing, outboard of midspan, was observed crushed aft at an estimated 30-degree angle. The wing tip was found bent upward at an estimated 45-degree angle. Compressive buckles were observed on the wing's upper surface. The outboard portion of the right wing, at the leading edge, was observed bent in an upward and aft direction. The engine compartment was observed crushed in an aft and upward direction. The left main landing gear was found broken from its supporting structure in an aft direction. Compressive buckles were present in the skin on the left side of the fuselage and in the floor beneath the front seat. The empennage appeared undamaged. All of the airplane's flight control surfaces were found attached to the airframe. The integrity of the entire flight control system was confirmed between each flight contro
The trainee-pilot's failure to maintain altitude during a low level turn. Contributing factors were the pilot-in-command's diverted attention inside the airplane, his failure to report the trainee's deficient airplane handling abilities, and the shoulder harness's incorrect seatback attachment location which was not rectified during required inspections.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
