SANTA ANA, CA, USA
N67421
Cessna 152
While the solo student pilot of the Cessna 152 was on downwind leg for landing, the air traffic controller directed the student's attention to a Boeing 757 aircraft that was preceding the student's aircraft for landing on the parallel runway. The threshold of the parallel runway is abeam and 500 feet to the right of the runway the student was to land on. The controller then advised of a 10-knot quartering headwind from the right, issued a wake turbulence precaution, and cleared the student pilot for the landing option. Witnesses reported that as the student pilot was on final approach, descending through approximately 100-foot altitude (agl), the aircraft abruptly rolled inverted and crashed short of the runway threshold. The Safety Board prepared a Study of Wake Turbulence Encounter using data from the Boeing 757's flight data recorder, tower communication tapes, and tower reported surface winds. The report concluded that the Cessna 152 descended into the Boeing 757's wake when the wake was 37 to 41 seconds old. The student's flight instructor told the Safety Board that the student, who had 136 hours of dual instruction and 20 hours of solo flight time, had received instruction in wake turbulence avoidance at three points in ground instruction. Furthermore, the instructor said that training as they had at the air carrier airport, most flights involved wake turbulence avoidance.
HISTORY OF FLIGHT On June 23, 1998, at 1707 hours Pacific daylight time, a Cessna 152, N67421, rolled abruptly, pitched down, and impacted terrain while on final landing approach at the John Wayne Airport, Santa Ana, California. The aircraft was destroyed and the student pilot was fatally injured. Visual meteorological conditions prevailed for the instructional flight that was operating in the airport traffic pattern performing takeoffs and full-stop landings. Witnesses reported that the aircraft was on a stabilized short final approach to runway 19L, approximately 100 feet agl, when the wings of the aircraft abruptly rolled approximately 90 degrees and the nose dropped. There is disagreement among witnesses whether the aircraft rolled to the right or to the left. In 2 or 3 seconds, the aircraft achieved a near vertical, nose-down attitude, which continued to impact. The witnesses reported that a Boeing 757 (later identified as American Airlines flight 2154) aircraft had landed on parallel runway 19R, upwind of runway 19L, approximately 30 seconds prior to the accident, and that surface winds were from the southwest at approximately 10 knots. A witness also reported that a departing Boeing 737 aircraft had been holding short of runway 19R (between 19R and 19L) at the departure end, and was moving into position on runway 19R at the time of the accident. A private pilot witnessed the accident while working on the terminal ramp about 300 feet east of the accident site. He reported that the aircraft's descent and attitude looked normal on final approach. He estimated that the aircraft was at 50 to 100 feet agl and airspeed of approximately 50 knots, when the nose pitched up mildly and wings of the aircraft "snap" rolled to the right approximately 90 degrees and the nose dropped. In 2 or 3 seconds, the aircraft achieved a near-vertical, nose-down attitude, which continued to impact. In a followup interview, this witness reported that he knew the aircraft rolled to the right because he recalled seeing the landing gear from his perspective. He also added that the accident did not appear to him to have been a stall event, the airspeed appeared normal. A nonpilot witness who observed the accident from the 405 (San Diego) Freeway reported the approach was smooth and "perfectly normal" until the airplane "dipped" slightly left and then abruptly right until the wings were straight up and down and the aircraft dove to the ground. A flight instructor and (instrument) student who observed the accident while holding for takeoff on runway 19L at intersection kilo believed that they saw the aircraft roll to its left. Another flight instructor observed the accident from another aircraft on final approach behind the accident aircraft and said that, as he watched, the accident aircraft pitched up briefly, the right wing came up, and it rolled violently to the left until the wings were past vertical. It then dove to the ground. He said that it was extremely fast and violent and that both he and his student remember it rolling to the left. He said that the Boeing 757 had passed them up and landed a little long on runway 19R and that wake turbulence avoidance was definitely a factor. He and his student planned to remain high and land long on runway 19L using full flaps. He said that the accident aircraft was on or a bit below the VASI glidepath. He also said that traffic was quite heavy with 5 or 6 aircraft in the runway 19L pattern, plus departing and arriving jets on runway 19R. PERSONNEL INFORMATION The student pilot was enrolled in a FAR Part 61 course of instruction. His logbook recorded his first instructional flight in May, 1996, and his total flying time at the date of the accident was 156.4 hours, of which 136.4 were dual instruction hours and 20.0 were solo hours. His flight instructor, who had instructed him for the entire duration, characterized him as a cautious student who showed good judgement. The flight instructor said that the student's high number of flight hours was in part due to interruptions in his training due to business and personal issues, and in part due to the students own conservatism. According to the instructor, the student received instruction in wake turbulence avoidance at several points in his instruction. In the school's private pilot ground school, which he attended, wake turbulence was discussed twice, once in aerodynamics and a second time in weather, where the effect of wind on wake turbulence was discussed. At lesson number 10 in the syllabus, the student was required to watch a video instruction tape on wake turbulence. Finally, the instructor said, flying from John Wayne Airport, almost every flight involved wake turbulence avoidance. They had discussed wake turbulence on nearly every dual flight and the student had demonstrated positive wake turbulence avoidance "hundreds of times" while flying dual. He had also performed many landings on runway 19L while large aircraft were holding between runways 19R and 19L, by coming in high over their exhaust wake and landing long. AIRCRAFT INFORMATION According to the operator's records, the aircraft was dispatched with no deferred maintenance items (squawks) open. According to the two flight instructors who flew the two previous flights in the aircraft, one earlier on the day of the accident and the other the previous night, there were no mechanical discrepancies noted during their flights. According to the operator, it is their usual practice to always dispatch their aircraft with the fuel tanks full. The fueling vendor provided refueling records showing that the accident aircraft was fueled with 5.8 gallons some time after 1600 on the day of the accident. METEOROLOGICAL INFORMATION At 1717, the weather at John Wayne Airport was clear sky, visibility 20 miles, and wind from 210 degrees at 10 knots. According to the operator's "Aviation Weather Check form" (attached), the pilot obtained preflight weather information from the John Wayne Automatic Terminal Information Service (ATIS) at 1350. On the form the pilot noted a 3 - 4 knot crosswind component. COMMUNICATIONS John Wayne Tower was operating two local control frequencies at the time of the accident. Local control one (1) controlled runway 1L/19R and airspace west of the airport. Local control two (2) controlled runway 1R/19L and airspace east of the airport. The accident aircraft was in radio contact with local control two and the Boeing 757 (American 2154) was in contact with local control one. Runways 19L and 19R were in use. Prior to 1700, the pilot received a clearance for flight in the airport traffic pattern, taxied to runway 19L, and performed one flight in the runway 19L airport traffic pattern terminating in a full-stop landing and taxi-back for another takeoff. The accident occurred on the pilot's second flight of the day. According to the local control 2 tape transcript provided by the Federal Aviation Administration (FAA), the pilot was cleared for his second takeoff on runway 19L at 1701:54. At 1703:00, the tower controller advised the pilot to turn left 15 degrees and extend his upwind leg and that the tower would call his crosswind turn. At 1703:36, the tower instructed the pilot to turn crosswind leg and sequenced him number 3 for landing. The pilot acknowledged that he was turning downwind. Two other aircraft entered downwind behind the accident aircraft and the second aircraft was advised that he was number 5 for landing. At 1705:13, the controller asked the pilot of the accident aircraft if he had his traffic, a Cessna, in sight on base leg, ahead. The pilot replied affirmatively. At 1705:43, the controller asked the pilot if he had the Boeing 757 in sight on 3-mile final for runway 19R. The pilot replied affirmatively. The controller then transmitted: "cessna four two one maintain visual separation from the arriving boeing seven fifty seven caution wake turbulence runway one niner left cleared for the option wind two two zero at eight." The pilot replied: "four two one uh be a full stop cleared to land on." The controller replied: "four two one thanks runway one niner left cleared to land wind two two zero at eight." At 1707:51, an unidentified transmitter said "tower did you see that?" to which the controller replied affirmatively. On the local control 1 tape transcript, at 1703:07, the controller cleared America West (call sign "Cactus") flight 375, a Boeing 737 which was holding short of runway 19L at the approach end, to cross runway 19L and hold short of runway 19R between the runways. American flight 2154, a Boeing 757 aircraft, contacted the tower at 1703:48. The controller sequenced 2154 number 3 for landing on runway 19R and asked the flight to slow to final approach speed and issued clearance to land. At 1707:02, the controller cleared Cactus 375 to taxi into position and hold on runway 19R. At 1707:12, the controller cleared Delta Airlines flight 1724, which was holding on the ramp taxiway east of runway 19L, to "turn the corner" and hold short of runway 19L at the approach end. At 1707:35, the controller instructed American 2154 to exit the runway at taxiway echo near the departure end. At 1707:57, an unidentified transmitter said "tower did you see that?" to which the tower controller replied affirmatively. AIRPORT INFORMATION The accident aircraft was on approach to runway 19L, which is 2,887 feet long and 75 feet wide. The Boeing 757 aircraft (American 2154) landed on runway 19R, which is 5,700 feet long and 150 feet wide. The thresholds of two parallel runways are abreast of one another and are separated laterally, centerline to centerline, by 500 feet. FLIGHT RECORDERS The flight data recorder from American Airlines flight 2154 was downloaded by American Airlines. According to the recorder data, the radar altitude for flight 2154 reached zero at 1707:16 on the FDR clock. WRECKAGE AND IMPACT INFORMATION The accident location is inside the airport perimeter fence approximately 200 feet north of the runway 19L threshold and approximately 25 feet east of the extended runway centerline. The accident site is in a level clearway and is covered with natural grasses mowed about 6 inches high. The elevation is approximately 38 feet msl. All of the aircraft components were present at the impact location and there was no fire. Crash and rescue personnel sprayed the aircraft with suppressant foam. The aircraft was inverted and the longitudinal axis of the fuselage was aligned with the nose pointing approximately 320 degrees. The wings, still attached to the fuselage at the cabin ceiling carry-through structure and struts, were oriented with the left wing pointing to the northeast and the right wing pointing to the south. The aircraft exhibited crushing damage along a line extending approximately 45 degrees from the nose of the aircraft aft along the leading edge of the right wing to the wing tip, and the right wing was bent aft approximately 45 degrees. The right wing leading edge was crushed as far aft as the main spar at the root and was crushed aft to the aileron and downward at the tip. The vertical orientation of the crushing plane was approximately 80 degrees nose down. The left wing leading edge did not exhibit leading edge crushing damage. The tail cone section of the fuselage exhibited compression buckling aft of the baggage compartment and was bent downward (with respect to the longitudinal axis) approximately 20 degrees and to the right approximately 30 degrees. The engine was inverted under the nose of the aircraft with the longitudinal axis at approximately a 45-degree nose down angle with respect to horizontal on a heading of approximately 300 degrees. The fuselage firewall and instrument panel were formed over the accessory section of the engine and most of the instrument panel was destroyed. The propeller remained attached to the engine. Both blades were bent aft over their span approximately 20 degrees and one blade exhibited an S-shaped curve in the trailing edge. Both blades had chordwise striations on the face. There was a hole in the soil approximately 4 feet in front of the nose of the aircraft which was oriented north-south and was approximately 6 inches deep and equal in dimension to the span and chord of the propeller. Windshield Plexiglas was present in proximity of the hole. Starting approximately 3 feet northwest of the center of this mark there was a second mark on the surface of the ground oriented north-south which approximated the span and thickness of one wing. Debris from the right wingtip fairing was present at the north end of this mark. The aircraft was further examined at Aircraft Recovery Service, Compton, California, on June 25, 1998. The seat belt had been cut by rescue personnel and the shoulder belt was separated from the ceiling of the aircraft at its attach point. The flight controls were continuous to the rudder, elevator, and elevator trim tab. The aileron flight control cables were continuous except where marked cut for recovery, and the chain on the forward side of the control yolk was off the sprockets. The right-hand aileron actuator rod between the bellcrank and the actuator in the right wing was separated at the bellcrank rod end in the threaded portion of the rod. The separation was accompanied by bending. The flap actuator extension corresponded to the 30-degree flap position. The retract flap cable was separated approximately 5 inches from the left flap bellcrank and the extend cable was separated approximately 1 inch from the turnbuckle in the cabin ceiling. The cable strands at both separations were bright, shiny, and unfrayed. The left wing aft spar attach fitting at the wing root was separated from the wing and remained attached to the fuselage carry-through structure. The right fuel tank exhibited compression damage and was ruptured. The outlet nipple on the left tank was separated from the fuel line. The engine was mechanically continuous from the propeller shaft through the accessory case. The valves functioned and there was thumb compression when the engine was rotated. The number one cylinder exhaust pushrod and housing exhibited impact damage. Several ignition wires were broken from the magneto cases. The right magneto was separated from the engine accessory case at its base and sparked at all four electrodes when turned by hand. The left magneto did not spark when rotated and, when opened, was found to contain a water-like substance which resembled the fire suppressant foam. The magneto was otherwise mechanically intact. The ignition switch, found in the "both" position, was electrically ungrounded. The spark plugs were clean, dark gray in color, and unfouled. The carburetor float bowl assembly was broken from the carburetor base below the throttle valve. There was trapped fuel in the line supplying the gascolator and in the line from the gascolator to the carburetor. The carburetor inlet screen was free of debris. The inlet air filter was clear and the carburetor heat valve in the air box was in the heated air position. The exhaust muffler was crushed but was free of debris. TESTS AND RESEARCH A "Study of Wake Vortex Encounter" was prepared by a specialist in the Safety Board's Office of Research and Engineering. The report is attached. The specialist modeled the migration of the left wingtip vortex from the Boeing 757 (American flight 2154) and the flight path of the accident aircraft using data from recorded ATC radar, the 757's digital flight data recorder and the tower reported surface winds. The specialist determined that the flight path of the accident aircraft intercepted the 757's wake vortex approximately 650 feet from the runway 19L threshold at roughly 75 feet agl. At the interception, the 757's wake was 37 to 41 seconds old. ADDITIONAL INFORMATION An autopsy was performed by the Orange county Sheriff-Coroner and toxicology was performed by the FAA Civil Aeromedical Institute. The aircraft wreckage was released to Mr. Gary Wayne of Universal Aviation Management on July 17, 1998.
The failure of the pilot-in-command to identify a proper touchdown point on the runway and maintain an appropriate glidepath so as to remain clear of vortex turbulence from the preceding large aircraft. A factor in the accident was the pilot's failure to initiate a go-around in the known presence of vortex turbulence.
Source: NTSB Aviation Accident Database
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