El Cajon, CA, USA
N38137
Piper PA-28-181
Radar data disclosed that the pilot flew the airplane from the departure airport toward the accident site, with the last recorded target at 610 feet above ground level (agl) over rising mountainous terrain. The floor of the radar coverage in the area was about 200 feet agl. The accident site was located at an elevation of about 2,293 feet mean sea level (msl) on the slope of a bowl-shaped box canyon about 25 nautical miles (nm) from the departure airport. In character, the canyon and surrounding hills were steeply sloped, averaging between 60 to 80 degrees, with the tops of the canyon terrain about 700 feet higher than the accident site elevation and 1,000 feet laterally in front of the wreckage. An analysis of the airplane's climb performance capability found that a lateral distance of 2 miles would be required to climb 700 feet. Ground scar analysis, impact signatures, and wreckage fragmentation patterns disclosed that the airplane impacted in a descending steep vertical nose down attitude traveling downslope. The impact geometry was consistent with the airplane encountering an accelerated stall while attempting a course reversal in the canyon. The width of the canyon immediately surrounding the wreckage measured about 1,250 feet. With a turn radius of 637.5 feet, and airspeed of 99 knots (maneuvering speed), the bank angle required for the airplane to complete a 180-degree turn was a minimum of 55 degrees. According to stall speed versus angle of bank data, the stall speed would be 55 knots at 55 degrees of bank. No evidence of mechanical malfunction or failure was found during a post accident examination of the airplane and engine. The pilot had accumulated 75 hours total flight experience, of which about 2 hours was in the same make and model as the accident airplane and acquired in the location of the departure airport.
HISTORY OF FLIGHT On July 13, 2007, about 1745 Pacific daylight time, a Piper PA-28-181, N38137, departed controlled flight and collided into the slope of a canyon near El Cajon, California. National Air College, Inc., was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The private pilot and one passenger were killed. The airplane was substantially damaged. The personal local area flight departed Montgomery Field, San Diego, California, at 1701. Visual meteorological conditions prevailed, and no flight plan had been filed. According to the operator, the pilot scheduled the airplane about 2 days prior to the accident flight. A lineman, employed by the operator, reported fueling the airplane with full fuel just prior to the accident flight. While fueling the airplane, he observed the pilot and passenger performing a preflight inspection. Records established that the airplane was fueled with the addition of 28.9 gallons of aviation fuel. Recorded radar data was obtained and reviewed by a National Transportation Safety Board investigator. The data covering the area of the accident was supplied by the Federal Aviation Administration (FAA) in the form of a National Track Analysis Program (NTAP) printout from Southern California Terminal Radar Approach Control (Southern California TRACON). As the airplane did not have a discrete transponder code, investigators reviewed the primary targets for the accident time frame and proximity to the anticipated flight track of the airplane. Southern California TRACON radar data disclosed a series of approximately equidistant radar returns from 1701:41 to 1714:07. The data was consistent with the accident airplane flying in a northeasterly direction. The radar plot stretched over a distance of approximately 20 nautical miles (nm) in 13 minutes 38 seconds, equating to a radar-derived ground speed of about 88.1 knots. The last radar return was recorded southwest of the accident location, approximately 7.6 nm from the accident location on a true course of 045 degrees. The target was identified at 1701:14 on Mode C (squawk 1200), located adjacent to Montgomery Field at a reported altitude of 500 feet mean sea level (msl). The track, starting on a northeast direction, increased in altitude and made a right turn towards the southeast. At 1704:30, the target was 4 miles east of Montgomery Field, climbing though 2,000 feet msl. The target momentarily turned to a northern direction, and then established a northeastern heading. According to the FAA, this momentary direction change coincided with an air traffic controller advising the accident pilot to turn north to avoid arriving traffic. During the proceeding 7 minutes, radar returns disclosed a gradual climb to a maximum altitude of 3,800 feet msl. Beginning at 1711:17, radar returns revealed a trend of decreasing altitude while terrain elevation was increasing, which continued for the last 3 minutes until the track ended. The last return occurred at 1724:07, with a reported altitude of 2,400 feet msl and the corresponding terrain elevation of about 1,790 feet, equating to an approximate altitude of 610 feet above ground level (agl). At that location, the Southern California TRACON radar floor was about 200 feet agl. PILOT INFORMATION A review of FAA airman records revealed the pilot held a private pilot certificate with a rating for airplane single engine land, issued on February 19, 2007. The pilot additionally held a second-class medical certificate that was issued on January 3, 2007, with no limitations. Copies of the pilot's personal flight logbooks were obtained by the Safety Board investigator-in-charge (IIC). A review of the logbooks disclosed that the pilot had accumulated 75 hours total flight experience, of which about 73 hours was amassed in Cessna airplanes, and the remaining 2 hours in the accident airplane. Following the obtainment of his license, the pilot recorded making three flights. The first entry was recorded as a 3.3-hour solo cross-country flight in a Cessna 172 conducted in Florida. The other two flights were documented as being instructional flights conducted in the accident airplane over a duration of 1.2 and 1.1 hours, respectively; both flights departed from Montgomery Field. Safety Board investigators interviewed the certificated flight instructor (CFI) that had given the accident pilot a checkout that enabled him to rent the accident airplane. The CFI reported that as part of the checkout, he had flown with the accident pilot two times prior to the accident, occurring on July 3 and July 10, 2007. He noted that during their initial conversations, the pilot stated that he intended to obtain his instrument rating after the checkout phase; the accident pilot had commented that he aspired to be a bush pilot. The CFI further stated that prior to the initial flight, the pilot had conveyed that he wanted to receive familiarization training in the San Diego area, as he had just moved from Florida. He added that he was additionally not accustomed to mountainous terrain and had never flown in vicinity of mountains. The initial flight departed from Montgomery Field and encompassed basic air work and area familiarization. The second flight, and last with the CFI, comprised basic instrument flight training maneuvers (e.g. compass turns, etc.). He noted that he had never taken the accident pilot near the area of the accident, nor had the pilot inquired about the terrain in that area. The CFI added that he believed the accident pilot to be a competent pilot, diligent with utilizing checklists. He was not aware that the accident pilot was planning to fly the airplane on the day of the accident and noted that they had never discussed the flight. A search of the FAA airman records database disclosed no record that the passenger had ever held any grade of pilot certificate. AIRCRAFT INFORMATION The single engine, low wing Piper PA-28-181 (serial number 28-7790522), was manufactured in 1977. It had accrued a total time in service of 10,288 hours. Review of the aircraft maintenance records disclosed that a 100-hour inspection was completed on June 28, 2007, 13 hours prior to the accident. The most recent annual inspection was completed on April 28, 2007, 123 hours prior to the accident. The Lycoming O-360-A4M engine, serial number L-23208-36A, had accumulated a total time in service of 10,150 hours. The engine had accrued 1,169 hours since the most recent major overhaul. Both the engine's annual and 100-hour inspections were accomplished on the dates noted for the airframe. No unresolved maintenance discrepancies were noted during the records review. The Safety Board IIC obtained fueling records documented by the operator. The records disclosed that the accident aircraft was last fueled on the accident date with the addition of 28.9 gallons of 100LL aviation fuel. Performance The performance data was calculated using information from the Piper Archer II PA-28-181 Pilot Operating Handbook for airplane serial numbers 28-7790001 and after, which was applicable to the accident airplane. For the purpose of the calculations, investigators utilized an estimated gross weight at the time of the accident to be 2,060 pounds, which was derived by the assumption of 180 pounds of fuel on board and a combined total weight of pilot and passenger of 340 pounds; the airplane's empty weight was about 1,540 pounds. Using the Ramona, California, airport temperature of 31 degrees Celsius (see Meteorological Section of this report), and the aforementioned estimated weight of 2,060 pounds, performance charts indicated a possible climb rate of about 500 feet per minute at the accident site elevation. From the accident site's elevation of 2,293 feet, the peak of the canyon's rim rose about 700 feet over a distance of 1,000 feet. Based on the airplane's estimated rate of climb performance and best rate of climb airspeed, a distance of 2.04 miles (10,800 feet) would have been required to climb 700 feet. A Safety Board investigator additionally calculated turning performance using the measured widths of the canyon and referencing Aerodynamics for Naval Aviators (NAVWEPS 00-80T-80), Figure 2.29, General Turning Performance (Constant Altitude, Steady Turn). The approximate width of the entire bowl-shaped canyon was 2,600 feet when measured using a topological mapping program. The terrain immediately surrounding the wreckage measured an approximate width of 1,250 feet. With a turn radius of 1,300 feet and airspeed of 76 knots (best rate of climb), the airplane's bank angle equated to 22 degrees. At 99 knots (maneuvering airspeed), the airplane's bank angle totals 35 degrees. With a radius of 637.5 feet (the immediate surrounding terrain) and 76 knots, the bank angle required is 42 degrees. At 99 knots, the airplane's bank angle required equates to 55 degrees to complete the turn. According to stall speed versus angle of bank data, at the anticipated weight of the airplane, with flaps set to 0 degrees, the stall speed would be 50 knots indicated airspeed at 22 degrees of bank varying to 63 knots at 55 degrees of bank. With a flap setting of 40 degrees, the stall speed would be 43 knots indicated airspeed at 22 degrees of bank varying to 55 knots at 55 degrees of bank. METEOROLOGICAL INFORMATION The closest official weather observation station was in Ramona, located about 10 nm northwest of the accident site at an elevation of 1,395 feet msl. An aviation routine weather report (METAR) for Ramona was issued at 1753. It stated: winds from 280 degrees at 9 knots; visibility 10 miles; skies clear; temperature 31 degrees Celsius; dew point 9 degrees Celsius; altimeter 29.96 inches of mercury. WRECKAGE AND IMPACT The accident site was located on the slope of a canyon about 25 nm from Montgomery Field, on a magnetic bearing of 045 degrees. In character, the canyon and surrounding hills were steeply sloped, averaging between 60 to 80 degrees, and populated by scattered manzanita shrubs and other brush typical of the southern California inland region. The main wreckage was located at an elevation of about 2,293 feet msl. The area of the accident site was surrounded by numerous other canyon formations, in the mountainous area adjacent to the El Capitan reservoir. The canyon was comprised of equally sloped terrain that ended in a semi-circular enclosure similar to a bowl-shape; the widest area across was about 1, 220 feet. The slopes that made up the canyon formation stretched about 3,000 feet in height. The main wreckage came to rest on the south-southeast side of a 70-degree slope, with the wings and tail section partially attached to the fuselage. The cabin was inverted, orientated on a bearing of 105 degrees. The left wing was separated at the wing root and folded under the cabin, aligned parallel to the right wing. The empennage was attached to the airframe by a small section of sheet metal and cables; it was askew from the main wreckage, oriented on a near perpendicular bearing of about 360 degrees. The tail cone was pointed upslope, with the left portion of the stabilator resting on a boulder. All control surfaces were accounted for at the accident site. The cabin roof was crushed inward, though the bottom flooring remained intact. There was severe crush deformation from the front cabin seats forward, with the engine pushed aft toward the cabin. The firewall was imbedded in the engine and the engine mounts were broken. Portions of the cowling were distributed in the surrounding wreckage areas. A path of wreckage debris and ground scars was noted about 15 feet upslope of the main wreckage, extending on a 132-degree magnetic bearing. The debris was scattered around an area about 40 feet long by 6 feet wide, with the propeller embedded in the center. Shards of a red lens cover, consistent with a wingtip navigation light, was about 20 feet to the right (southwest) of the propeller location. Adjacent to the lens fragments was a portion of the left wing tip. Similar shards of blue lens were embedded in the dirt about 20 feet to the left (northeast) of the propeller. The nose wheel fairing was the piece of wreckage found the farthest upslope, located between the propeller and the blue lens about 10 feet up. The right wing was attached to the airframe and inverted. It extended down slope from the cabin on a bearing of 045 degrees, and was positioned parallel to the horizon, suspended approximately 10 feet above the sloping ground. The wing exhibited upward leading edge crush damage along the entire length. The right fuel tank had an 18-inch triangular-shaped breach approximately 5 feet from the root. No fuel was observed in the compromised tank or surrounding area. The wing flap control surface remained connected to its respective attach points and was extended approximately 30 degrees; the aileron was physically in the neutral position. The left wing came to rest along the canyon slope below and parallel to the right wing. The wing exhibited upward leading edge crush damage along the entire length, which extended about 7 inches aft. The flap and aileron were physically in a neutral position. The wingtip and navigation lights were not on the wing. The fuel tank was perforated and no fuel was found. The left main gear was intact and attached to the wing, and the gear fairing displayed minor crush damage in the front section. The separated empennage section included the entire tail section about 65 inches forward of the tail cone. The separation was at station 156.00, just aft of the rear windows. The stabilator was intact, with the only damage observed being a slight dent in the right outboard tip. The trim tab was physically in the neutral position. The rudder and its respective navigation and beacon lights were intact. The engine was aligned with the cabin and had come to rest inverted. Investigators performed an external visual examination of the engine, but were unable to move the wreckage, as it had come to rest in precarious position. The engine had sustained crush damage primarily to the left side and ductile crushing was noted to the exhaust risers and tubes. Cylinders number 1 and 3 were visible, facing upward, with number 2 and 4 cylinders presumed to be buried in the soft dirt slope. Investigators removed the bottom spark plugs of cylinder 1 and 3; they were gray in color with slightly oval electrodes. According to the Champion Aviation Check-A-Plug AV-27 Chart, these spark plug signatures correspond to normal engine operation. A borescope examination of the two aforementioned cylinders revealed no foreign object damage, no evidence of detonation, and no indication of excessive oil consumption. The inside of the exhaust pipe was dry, free of oil, and exhibited light brown deposits, which the Lycoming representative stated was consistent with normal operations. The exhaust stacks exhibited malleable crushing damage. Portions of a cylinder head and two push rods were located about 15-feet upslope from the engine. There was no evidence of catastrophic mechanical malfunction with the engine. Investigators found the nose landing gear assembly above the engine. It was separated in the vicinity of where it attached to the firewall. The oleo strut had snapped in a rearward direction at the base of the strut. The wheel remained attached by the fork link. The propeller was separated from the engine, and came to rest approximately 10 feet above the main wreckage at the base of a 10-foot dome-shaped rock. The tip of one blade, measuring 10 inches in length, had separated in a jagged s-pattern and was found adjacent to the remaining blade. The blade exhibited chordwise scrape marks along its entire length and leading edge gouges. The entire blade curved in an approximately 30-degree rearward bend. Buckling was exhibited along the entire trailing edge. The other propeller blade exhibited similar leading edge grooves. On the leading edge, at the area the blade had separated, the metal was bent 90 degrees away from the direction of travel. The nose landing light was ad
the pilot's inadequate in-flight decision to attempt low altitude flight operations into a box canyon in mountainous terrain, and his failure to maintain an adequate airspeed while maneuvering to reverse direction, which led to an accelerated stall and spin.
Source: NTSB Aviation Accident Database
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