N737EJCessna 172N · 1978

On January 20, 2008, at 1534 Pacific standard time, a Cessna 172N, N737EJ, and a Cessna 150M, N4008V, collided while maneuvering about 1.4 miles south-southwest of the Corona Municipal Airport (AJO), Corona, California. The midair collision occurred at a location and flight direction consistent with the Cessna 172N on an approximate 45-degree entry leg into Corona's left-hand traffic pattern for runway 25, while the Cessna 150M was entering the pattern's downwind leg, following takeoff from runway 25. The commercial pilot and passenger in the Cessna 172N were killed. The pilot and pilot-rated passenger in the Cessna 150M were also killed, along with one person on the ground who was impacted by falling components from the Cessna 150M. Both airplanes were fragmented during the collision sequence, and were destroyed during their uncontrolled nose down descents into underlying cars, buildings, and parking lots. The Cessna 172N was operated by Funoutside, based in Fullerton, California. The Cessna 150M was operated by Fly Corona, Inc., d.b.a. Corona Flight Academy, based in Corona. The personal flights were operated under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed at the time, and no flight plans were filed. The Cessna 172N's local area flight originated upon its renter pilot's departure from Fullerton, where the airplane was based, at an undetermined time. The Cessna 150M's flight originated from Corona, upon its renter pilot's departure about 1532.

Several witnesses reported being within a 1/2-mile radius of the accident site and observed or heard the midair collision. The National Transportation Safety Board investigator and Corona Police Department personnel interviewed witnesses who observed the airplanes seconds prior to and during the collision sequence. None of the witnesses reported observing evidence of fire or smoke trailing from either airplane prior to the collision.

One of the witnesses was located about 1/2-mile southwest of the accident site in the backyard of her hillside residence, at an approximate elevation of 750 feet mean sea level (msl). This witness reported continuously observing both airplanes cruising toward each other for at least 5 seconds preceding the midair collision. In pertinent part, the witness stated that the airplane that flew nearly over her location was flying in a northerly direction toward AJO, while the other airplane was flying in an easterly direction and was south of the airport. Neither airplane appeared to change course, rock their wings, or commence an avoidance maneuver prior to colliding. The witness indicated that, from her vantage point, it appeared as though the northbound airplane and the eastbound airplane collided with each other at nearly a perpendicular angle. The northbound airplane impacted the right side of the eastbound airplane, near the midsection of its fuselage. Upon colliding, parts of the airplanes separated from each other; the parts looked like wings. The witness further reported that as she observed the airplanes, no evidence of fire or trailing smoke was noted. The engine of the northbound airplane sounded typical of a normally operating light airplane engine, and no missing or sputtering sound was evident.

Recorded radar data was received from the Federal Aviation Administration's (FAA) Southern California Terminal Radar Approach Control facility (SOCAL) for the time and location of the accident. The data was reviewed by FAA and Safety Board personnel. The data included two targets that exhibited flight paths (speeds, altitudes, courses) that matched the convergent tracks of the accident Cessna airplanes. (See the airplanes' Flight Path Diagrams that are included in the docket for this accident.) In summary, the radar depicts the following tracks for the airplanes:

Cessna 172N Flight Track

During the last 5 minutes of the airplane's recorded flight, starting about 1529:27, the Cessna 172N was about 8 statute miles east of AJO, and about 5 miles south of the Riverside Municipal Airport. The Cessna was cruising in a westerly direction and was at 2,400 feet, as indicated by the airplane's altitude reporting transponder. The Cessna proceeded on a course nearly parallel to, but south of, Highway 91, and it descended.

By 1533:51, the westbound Cessna 172N had descended to 1,300 feet and was about 2 miles south-southwest of AJO. About this time, the airplane commenced a 110-degree (approximate) right turn consistent with a maneuver that would position the airplane onto the 45-degree entry leg into the traffic pattern for runway 25. About 1534:05, the airplane was established on the entry leg. Its average ground speed was about 106 knots, and it was tracking on an approximate 21-degree magnetic course while remaining at 1,300 feet. The collision occurred when the Cessna 172N was within 0.1 mile north of Highway 91, about 13 seconds after establishment on the traffic pattern's entry leg, about 1534:18.

Cessna 150M Flight Track

The Cessna 150M's flight track began upon the airplane's takeoff from runway 25, and it ended about 1.4 miles south-southwest of the airport during the midair collision. About 1532:42, the airplane was airborne and was passing the departure end of runway 25. (For undetermined reasons, SOCAL did not receive and/or record any altitude information from the airplane's altitude reporting transponder).

About 1/2-minute later, the airplane began turning in a southerly direction toward the left crosswind leg. By 1533:42, the airplane was flying southbound, was established on the left crosswind leg, and was about 1.0 mile southwest of the runway's end. The airplane subsequently turned left toward the downwind leg. Between 1534:05 and the last radar hit at 1534:14, when the airplane was about 0.1 mile north of Highway 91, the airplane was tracking on an approximate 121-degree magnetic course at an average ground speed of 74 knots.

Approximately 1/2 dozen automobiles sustained various degrees of impact damage. One commercial structure's roof was penetrated by a falling engine and attached airframe components.

Cessna 172N Pilot, Left Seat

The pilot, age 73, held a commercial pilot certificate with the following ratings: airplane single-engine land, rotorcraft-helicopter, and instrument airplane and helicopter. The pilot's flight record logbook indicated his total flight time was about 4,190 hours. The pilot's last flight review was accomplished in a Cessna 172 on December 20, 2007.

The pilot's last aviation medical certificate was issued January 2007, in the third class, with the restriction that he must have available glasses for near vision. The pilot's reported height and weight was 71 inches and 212 pounds.

Cessna 172N Passenger, Right Front Seat

A review of FAA records indicated that the passenger did not hold any FAA certificate. He had no FAA record of flight time.

Cessna 150M Pilot, Left Seat

The pilot, age 24, was issued a combined student pilot and first class aviation medical certificate (without restrictions or limitations) on November 1, 2007, and a private pilot certificate on November 25, 2007, with the following ratings: airplane single-engine land. The pilot successfully passed an examination for issuance of an instrument airplane rating on January 20, 2008, about 3 hours prior to the accident flight.

The designated pilot examiner (DPE) who administered the instrument rating check ride reported that during the oral examination he covered special emphasis areas related to operations at uncontrolled airports, collision avoidance, and proper scanning techniques. The examiner reported that because their "flight profile included Corona Airport, I provided additional cautionary admonishment related to this operation." He further stated that the pilot's "flight instructor reinforced my statements related to the hazards of operating at Corona Airport." The DPE also reported that the pilot's "skill and knowledge exceeded that commonly found in applicants with similar flight experience."

The pilot's flight record logbook was not recovered for examination. A review of FAA records dated January 20, 2008, indicated that his total flight time was 141 hours. His total dual instruction received was 44 hours. The pilot reported his height and weight were 72 inches and 190 pounds.

According to Air Corona's owner-operator, the pilot was authorized to rent the accident airplane. However, the passenger in the airplane (who occupied the right seat) had not been checked out at the flight school. Accordingly, he was not authorized to rent the airplane.

Cessna 150M Passenger, Right Seat

The pilot-rated passenger, age 20, held a private pilot certificate with the following ratings: airplane single-engine land and instrument airplane. The pilot was issued a private pilot certificate in May 2006, and an instrument rating in October 2007. The pilot held a first-class aviation medical certificate that was issued in March 2006, with the limitation that he wear corrective lenses. On the October 2007, pilot certificate, the pilot indicated his height and weight was 72 inches and 170 pounds.

The pilot's flight record logbook was located in the accident airplane. The last flight recorded was dated November 20, 2007. (The pilot's flight time listed in the Safety Board's accident report is limited to data in this logbook.) The pilot's total flying experience was reported as 193 hours, of which about 87 hours were in the Cessna 150/152, and 106 hours were in the Cessna 172.

Cessna 172N

The four-seat, high-wing, fixed-gear airplane, serial number 17269358, was manufactured in 1978. It was powered by a Lycoming O-320-H2AD 160-horsepower engine, and it was equipped with a 75-inch diameter fixed pitch propeller. The airplane was maintained on a program of annual and 100-hour inspections. A review of the flight school's maintenance records showed an annual inspection was completed on April 26, 2007, and a 100-hour inspection was completed on September 27, 2007. The airplane's total time on the accident date was about 3,564 hours.

Cessna 150M

The two-seat, high-wing, fixed-gear airplane, serial number 15076677, was manufactured in 1975. It was powered by a Continental O-200-A 100-horsepower engine, and it was equipped with a 69-inch diameter fixed pitch propeller. A review of the flight school's maintenance records showed an annual inspection was completed on October 30, 2007, and a 100-hour inspection was completed on December 29, 2007. The airplane's total time during the last inspection was 10,890 hours. The engine had been operated about 723 hours since its last overhaul.

Climb Performance

According to the Cessna 150M's "Owner's Manual," at the airplane's maximum certificated 1,600 pound gross weight, normal climbs are conducted at 75 to 85 miles per hour (65 to 74 knots). Under standard atmospheric sea level conditions, the maximum rate of climb airspeed is 78 miles per hour (68 knots). At this airspeed, the "Owner's Manual" indicates a Cessna 150M's maximum rate of climb would be 670 feet per minute. The Safety Board investigator calculated the airplane's gross weight during the accident flight, and it was approximately 1,600 pounds.

At 1456, Corona reported the following weather conditions: wind from 260 degrees at 9 knots; 10 miles visibility, sky clear; temperature/dew point 17/02 degrees Celsius; and altimeter 29.91 inches of Mercury.

At 1556, Corona reported the following weather conditions: wind from 270 degrees at 7 knots; 10 miles visibility, sky clear; temperature/dew point 16/02 degrees Celsius; and altimeter 29.91 inches of Mercury.

The FAA and Lockheed Martin Flight Services reported having provided no weather-related services to N737EJ or N4008V on January 20, 2008.

According to the witness who was located on a hillside about 1/2-mile south of the accident site, at the time of the accident the sky was clear and blue, the wind was light and variable, and the temperature was about 60 degrees Fahrenheit.

According to the FAA coordinator, no FAA facility recorded any communications with either of the accident airplanes during the 15-minute period prior to the accident. AJO management reported that the airport does not record communications on the common traffic advisory (UNICOM) frequency, 122.7 MHz.

During the approximate 10-minute period prior to the collision, several pilots were flying in the vicinity of Corona and were approaching or departing from runway 25, which was the active runway. None of the pilots reported to the Safety Board investigator having heard either of the accident pilots broadcast their respective airplane registration numbers along with their intentions.

AJO is managed by the City of Corona and is open to the public. As published in the FAA's "Airport/Facility Directory," the airport's elevation is 533 feet msl. Runway 25 is 3,200 feet long. The recommended traffic pattern altitude is 1,533 feet msl (1,000 above ground level), and runway 25 uses a left-hand pattern.

The airport is uncontrolled. The Common Traffic Advisory Frequency (CTAF/UNICOM) is 122.7 MHz. Neither the City of Corona nor fixed base operators at the airport record air traffic communications.

The accident site was located in a commercial business area within the City of Corona. Airplane wreckage from the midair collision fell onto streets, cars, and occupied buildings, resulting in the sole ground injury (fatality). Evidence of fuel was observed in both airplanes and on the ground adjacent to their severed wings. There was no fire. The approximate ground elevation at the accident site is 590 feet msl.

The Safety Board investigator's on scene examination of the accident site revealed fragmented components of the Cessna 172N along a northerly track, with the main wreckage located about 800 feet north of the southern-most wreckage of the Cessna 150M. Portions of both airplanes (landing gears, fuselage skin, instruments) were found commingled in the wreckage of the Cessna 172N. The principal axis of the Cessna 172N's wreckage distribution path was about 25 degrees, magnetic. The principal axis of the Cessna 150M's easterly 320-foot-long wreckage path was about 78 degrees, magnetic.

Cessna 172N Examination

The Cessna 172N's main wreckage was principally found in one location. The airplane was in a parking lot near a Nissan car dealership, and it had impacted two parked cars. The entire cockpit was crushed. All of the airplane's components were found in the vicinity of the main wreckage with the exception of the right wing outboard of the flap/aileron junction, which was found near the wreckage of the Cessna 150M. The Cessna 172N's fuselage floor was crushed in an aft direction. The center wing section was observed separated from the lower fuselage floor, which was compressed aft. The main landing gear remained attached to the fuselage floor, and the nose gear was observed beneath the nose section of the fuselage. The doors were crushed aft. The empennage was attached to the fuselage and was intact.

The Cessna 172N's left wing and inboard portion of the right wing remained attached to the center wing section of the fuselage. All flight control surfaces remained attached. The continuity of the flight control cable system was confirmed, with all preimpact separations bearing signatures consistent with overload. The elevator trim tab actuator was in a 5-degree down position, and the wing flaps were fully retracted, according to the Cessna Aircraft Company participant.

The propeller exhibited s-bending, chordwise scratching, and leading edge nicks. The engine's crankshaft flange was separated from the crankshaft, and the crankshaft could not be rotated. The fuel strainer bowl was not observed, but the screen remained attached to the strainer base and was clear of debris. No evidence of preimpact abnormalities was noted with the engine case or accessories. No evidence of preimpact oil leaks or fire was noted.

Cessna 150M Examination

The Cessna 150M's airframe structure was separated into several sections. Beginning at the western side of the wreckage distribution were the left and right wings, which were separated from the airplane. The empennage was located east of the wings. These components were found outside on the ground. The engine, propeller, cockpit, and undercarriage were found at one location at ground level inside a building, which bore an engine-sized hole in its roof, at the extreme eastern side of the wreckage distribution path. Instruments from the airplane were located on the roof and inside the building. Additionally, portions of the Cessna 150M's fuselage were intermingled with the Cessna 172N's fuselage.

The top of the vertical stabilizer and navigation light assembly were observed separated from adjacent structure. The right side of the rudder was painted blue, and the paint appeared to match a smear of blue paint observed on the top of the Cessna 172N's left wing, which was white.

The propeller exhibited chordwise scratching and leading edge nicks. The engine was impact damaged. The engine's crankshaft flange was separated from the crankshaft, and the engine's crankshaft could not be rotated. No debris was noted in the engine's fuel strainer bowl. No evidence of preimpact abnormalities was noted with the engine case or accessories. No evidence of preimpact oil leaks or fire was noted. The wing flaps were found retracted.

Autopsies were performed on the three pilots by the Riverside County Sheriff-Coroner, Perris, California. The autopsy findings indicated that the Cessna 172 pilot died from "multiple blunt impact." The two pilots in the Cessna 150 died from "multiple blunt force trauma."

Forensic toxicology was performed on specimens from the three pilots. The Civil Aerospace Medical Institute's (CAMI's) Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, reported that no ethanol or any screened drugs were detected.

Airplane Contact Examination

All of the airplane wreckage was recovered from the accident site, and an examination for contact signature evidence between the airplanes was accomplished. Evidence was observed of an intrusion by the propeller and engine compartment structure of the Cessna 172N into the right side of the Cessna 150M's cockpit.

Laceration signatures consistent with propeller blade penetration marks were observed on the lower portion of the Cessna 150M's severed right wing lift strut, right cockpit floor, and right seat. The angle of the cut floor was about 20 degrees, as measured from the airplane's longitudinal axis (see photograph).

The bottom of the Cessna 172N's white painted left wing bore a series of scratch marks and paint transfer signatures consistent with blue painted portions of the Cessna 150M's fuselage. A several inch-long leading edge span of one propeller blade was found dented. The size of the dent was consistent with the size of the Cessna 150M's severed right wing lift strut (see photograph).

Based upon the orientation of the scratch marks between the airplanes and the penetration evidence, the respective collision and convergence angles were calculated.

Collision and Convergence Angles

The collision (impact) angle describes the angle between the airplanes at impact. For example, if one airplane is on a 90 degrees (east) flight track when a collision occurs with an airplane that is on a 360 degrees (north) flight track, the collision angle would be 090 degrees.

Another angle, called the convergence angle, describes the relationship (in degrees left or right) between the airplane's heading and the location of the converging airplane. The convergence angle represents how far left or right the pilot would have to look to see the other airplane. In essence, it is the relative bearing from a forward-looking pilot to the converging airplane.

Radar Data and Calculated Collision and Convergence Angles

The last couple of recorded radar hits for the Cessna 172N and the Cessna 150M indicated these airplanes were converging on respective true courses of about 34 and 134 degrees. The midair collision occurred between successive radar antenna rotations and was within 5 seconds of the airplanes' last recorded positions. Based upon this radar data, the expected collision angle is calculated to be about 100 degrees (134 - 34 degrees). Also, based on the radar data, the convergence angles are calculated to be 31.5 degrees (Cessna 172N) and 48.5 degrees (Cessna 150M). (See Flight Path Diagrams in the docket. Note: when applying surface wind velocity to the radar recorded flight track data, the airplane's true airspeeds and headings varied by 5 knots and 5 degrees, at most.)

Measured Collision and Convergence Angles

The collision angle between the Cessnas was physically determined by measuring the mass intrusion signature of the Cessna 172N's propeller blade into the right side of the Cessna 150M's cockpit. The Cessna 172N's propeller nose cone contacted the right side of the Cessna 150M between the forward door post and the firewall. The Cessna 172N propeller had a 2.5-inch-long nick along its leading edge, and the right wing lift strut of the Cessna 150M was severed in an upward and forward direction. The Cessna 150M's floorboard, the right side seat rail, and the left side of the right seat were cut at a diagonal angle upward through the floorboard. These signatures correspond to a collision angle of about 70 degrees.

Parallel blue paint transfer lines and scratches at five locations on the bottom of the Cessna 172N's left wing indicated that the Cessna 172N's convergence angle was about 41 degrees. Based on this measurement, the Cessna 150M's convergence angle was calculated to be about 69 degrees. (See Flight Path Diagrams included in the docket.)

Visual Angles, Cockpit Visibility

The Cessna Aircraft Company provided the Safety Board investigator with a "Pilot View Chart" that delineates the limits of a pilot's field of view (visual angles) in Cessna 172 and 150 airplanes. The chart identifies the areas where pilots would have the capability of seeing objects located forward, downward, and sideways through the airplane windows before vision becomes obstructed by the presence of airframe structure. The chart does not take into account viewing limitations imposed by the presence of any other person, or object, in the adjacent front seat. The chart is based upon the stationary pilot's eye reference location and does not take into account variances in seat position.

Cessna 172 Visual Angle

In pertinent part, based upon Cessna's data, from the left cockpit seat in a Cessna 172, a pilot has the capability of seeing objects located directly ahead, and through a 52-degree left arc. Also, the pilot has the capability of seeing objects located 11 degrees downward when looking in a forward direction and 53 degrees downward when looking out the left side window.

Cessna 150 Visual Angle

In a Cessna 150, when looking in a forward direction, a pilot located in the left seat has the capability of seeing objects 32 degrees upward. Relative to the front of the airplane, a pilot has the capability of seeing objects located 34 degrees left and 58 degrees right. Also, the pilot has the capability of seeing 44 degrees downward and 20 degrees downward when looking out the left and right side windows, respectively. A pilot located in the right seat would have the same visual angles, albeit in opposite directions.

Airport Operations

In Chapter 13 of the FAA's "Pilot's Handbook of Aeronautical Knowledge," 2008 edition (FAA-H-8083-25A), the FAA provides guidance to pilots regarding operating in traffic patterns. In this midair collision investigation, the following two procedures from the Handbook are noted:

1. Enter pattern in level flight, abeam the midpoint of the runway, at pattern altitude, and a 1,000-foot above-ground-level altitude is the recommended pattern altitude, unless established otherwise.

2. If remaining in the traffic pattern, commence turn to crosswind leg beyond the departure end of the runway within 300 feet of pattern altitude.

AJO's elevation is 533 feet msl. The FAA's recommended minimum altitude to initiate the crosswind turn is 1,233 feet msl [533 + (1,000 - 300)].

Based upon the recorded radar data, the Cessna 150M commenced its crosswind turn about 3/4-minute after takeoff.

Gaining altitude at its 670-feet-per-minute maximum rate, the calculated maximum altitude that the airplane would have attained upon initiation of the crosswind turn is about 503 feet (3/4 x 670). With this altitude gain, the Safety Board investigator calculated that the crosswind turn was commenced about 1,036 feet msl (at least 197 feet lower than the FAA's 1,233 feet msl recommendation).

See and Avoid Regulations

Federal regulations concerning right-of-way rules (14 CFR 91.113) state, in part, the following: When weather conditions permit, vigilance shall be maintained by each person operating an aircraft so as to see and avoid other aircraft. In the case of aircraft converging at approximately the same altitude (except head-on, or nearly so), the aircraft to the other's right has the right-of-way. In addition, in the case of one aircraft overtaking another, the aircraft that is being overtaken has the right-of-way, and each pilot of an overtaking aircraft shall alter course to the right to pass well clear.

Role of the Pilot-rated Passenger

The occupant located in the Cessna 150M's right seat was a current pilot, and had the recent flying experience to carry a passenger. An instrument view limiting device (hood) was found in the wreckage. The Safety Board investigator was not able to ascertain whether the pilot who occupied the right seat was acting as a safety pilot, pilot-in-command, or had any flying responsibilities. The airplane was equipped with dual flight controls, which were reported as being functional. The airplane could be flown by either pilot from either seat.