LAX94FA048
LAX94FA048

History of Flight

On November 12, 1993, about 1117 hours Pacific standard time, a Beech V-35, N630AW, registered to and operated by the pilot, experienced an in-flight breakup, about 25 miles northeast of Shaver Lake, California. The airplane was destroyed. The certificated private pilot and three passengers received fatal injuries. The airplane was being operated as a visual flight rules (VFR) cross-country personal flight to Death Valley Monument Airport when the accident occurred. Instrument meteorological conditions prevailed in the accident area at the time. A flight plan was not filed.

The flight originated at Reid-Hillview Municipal airport, San Jose, California, about 0951 hours. After departure, the pilot was given a frequency change as he exited the airport traffic area. There was no further voice communication with the pilot. The flight was expected to arrive in Death Valley about 1100 hours. On November 13, 1993, the flight was reported as overdue.

National Track and Analysis Program (NTAP) radar data from the Oakland Air Route Traffic Control Center (ARTCC) was reviewed and a plot of the accident area was prepared by the Federal Aviation Administration (FAA). The airplane was not radar identified and the pilot was not receiving traffic advisories from the FAA. Radar data in the vicinity of the accident site was plotted from 1101:41 to 1121:40 hours. Radar data points from 1110:17 to 1117:38 hours were consistent with the location of the accident airplane.

At 1110:17 hours, the airplane was at 15,700 feet. The radar track was oriented on a northeasterly heading. As the flight continued to the northeast, the altitude continued to climb to 17,300 feet, and the radar track indicated a "U" turn toward the west. At 1117:26 hours, the NTAP indicated an altitude of 17,100 feet and the airplane turned back to the northwest. At 1117:38 hours, the last radar return indicated an altitude of 16,500 feet.

Search personnel located an emergency locator transmitter (ELT) signal from the airplane on November 15, 1993. The wreckage was located at about 1545 hours, about 10,000 feet mean sea level (msl).

The accident occurred during the hours of daylight at latitude 37 degrees 20.9 minutes N and longitude 118 degrees 51.2 minutes W.

Crew Information

The front seats of the airplane were both occupied by certificated pilots. No evidence was found that indicated who was manipulating the aircraft controls at the time of the accident.

The occupant of the left front seat (first pilot) held a private pilot certificate with an airplane single-engine land rating. The most recent third-class medical certificate was issued to the pilot on September 10, 1991, and contained no limitations. A third-class medical certificate is valid until the end of the 24th month of the date of issuance.

No personal flight records were recovered for the first pilot, and the aeronautical experience listed on page 6 of this report was obtained from a review of the FAA airman records on file in the Airman and Medical Records Center located in Oklahoma City. On the pilot's application for an FAA medical certificate on September 10, 1991, the pilot reported having accrued 600 flight hours, with 100 hours accumulated in the previous 6 months.

The occupant of the right front seat (second pilot) also held a private pilot certificate with a single-engine land rating. The most recent third-class medical certificate was issued to the pilot on January 6, 1993, and contained no limitations.

No personal flight records were recovered for the second pilot and the aeronautical experience listed in Supplement E of this report was obtained from a review of the FAA airman records on file in the Airman and Medical Records Center. On the pilot's application for an FAA medical certificate on January 6, 1993, the pilot reported having accrued 140 hours. No flight hours were indicated in the previous 6 months.

Aircraft Information

The airplane was originally manufactured as a model V-35TC which had a Continental TSIO-520-D engine installed as original equipment. On February 28, 1984, the airplane had accumulated 2,616.7 hours and, on that date, the engine was removed and replaced with a Continental IO-520-BA. The original logbooks were lost and a new record was initiated when the engine was changed. With the engine change, the airplane reverted to a model V-35. The manufacturer reported that the service ceiling for a model V-35 is 17,500 feet.

Examination of the maintenance records revealed that the airplane had accrued a total time in service of 3,207.95 flight hours. On February 5, 1992, the airplane was given an annual inspection and found to be unairworthy. The unairworthy items were listed as a fuel leak in the left wing, unsafe rudder and aileron rigging, ruddervator cable chafing, pitot heat inoperative, and a deteriorating induction inlet coupler duct. On April 1, 1992, the unairworthy items were repaired and the airplane was returned to service. At that time, the airplane had accrued 3,070.69 flight hours, 76.34 hours before the accident.

The engine had accrued a total time in service of 2,778.51 hours of operation. The maintenance records note that a major overhaul was accomplished on February 28, 1984, 591.51 hours of operation before the accident. An annual inspection was accomplished on the date specified above for the airframe.

Meteorological Information

The closest official weather observation station is Mammoth-June Lakes Airport, elevation 7,128 feet msl, which is located 16 nautical miles north of the accident site. At 1147 hours, a surface observation was reporting in part:

Sky condition and ceiling, estimated 1,500 feet overcast; visibility, 8 miles; temperature, 30 degrees F; dew point, 20 degrees F; wind, 210 degrees at 8 knots; altimeter, 29.98 inHg; remarks, mountain tops obscured all quadrants.

An automated weather observation station (AWOS) is also located at the Mammoth-June Lakes Airport. At 1101 hours, the AWOS was reporting:

Temperature, 31 degrees F; dew point, 20 degrees F; wind 240 degrees at 12 knots; altimeter, 29.79 inHg.

Bishop, California, elevation 4,145 feet msl, is located 23 nautical miles east of the accident site. At 1050 hours, a surface observation was reporting in part:

Sky condition and ceiling, estimated ceiling, 2,000 feet overcast; visibility, 10 miles in light snow; temperature, 36 degrees F; dew point, 32 degrees F; wind, 020 degrees at 15 knots; altimeter, 29.79 in Hg.

A National Transportation Safety Board meteorologist conducted a study of the accident area weather conditions. At 1000 hours, a surface weather map prepared by the National Weather Service (NWS) depicted a center of low pressure over southeastern Nevada. A cold front extended from the low, southwest to the San Diego, California area. A secondary trough extended from the low westward to the vicinity of Paso Robles, California. The weather system was moving eastward and extended across the central portions of California and Nevada.

An Aviation Area Forecast, valid until 1600 hours, was reporting extensive low clouds and precipitation across California. For the San Joaquin Valley scattered clouds at 1,500 feet, overcast skies at 4,000 feet, with visibility 3 to 5 miles in fog were expected. Widely scattered light rain showers, thunderstorms with light rain showers, were forecast, possibly in lines and/or clusters. Mountain areas were forecasted to have skies of 8,000 feet scattered, 12,000 feet broken, occasionally 8,000 feet overcast. Scattered light rain showers and/or snow showers were expected with the tops of the clouds layered to 24,000 feet.

Additionally, the area forecast was reporting that from Vandenberg Air Force Base to China Lake to 60 miles northwest of Bishop, California, widely scattered areas of light rain showers and thunderstorms, possibly in lines and/or clusters. The outlook for the forecast, which is valid from 1600 to 2200 hours, was for visual flight rules (VFR) conditions.

A 0700 hours terminal forecast for Bishop, California, was reporting in part: Sky condition and ceilings, 2,000 feet scattered, 6,000 feet broken, occasional ceiling 2,000 feet broken; visibility 3 miles in light rain/light snow showers; wind, 340 degrees at 15 knots, gusting to 25 knots. At 1400 hours, the forecast called for skies, 5,000 feet scattered, a chance of ceiling of 5,000 feet broken; wind, 360 degrees at 12 knots gusting to 20 knots; light rain showers until 1700 hours.

Several airman's meteorological information (AIRMETS) in-flight advisories were issued by the NWS at 0545 hours and were valid until 1200 hours. AIRMET Sierra was reporting instrument flight rules (IFR) conditions and mountains occasionally obscured in clouds and/or precipitation and/or fog. AIRMET Tango was reporting occasional moderate turbulence below 18,000 feet associated with an upper-level trough and cold front moving through the area. Turbulence was indicated to be locally severe in central and southern California. AIRMET Zulu was reporting light to occasional moderate mixed/rime icing in the clouds and precipitation from 8,000 to 18,000 feet.

Upper level winds reported at Oakland, California, at 12,000 feet to 18,000 feet msl, were 35 knots. Winds aloft reported at Desert Rock, Nevada, were 17 to 19 knots. Wind directions ranged from 360 to 200 degrees.

Visual satellite images of the accident area revealed the presence of generally overcast cloud conditions. A series of lenticular-shaped clouds were visible over the central Sierra Nevada Mountains. No radar echoes were reported in the area of the accident.

Wreckage and Impact Information

The airplane wreckage was examined at the accident site on November 17, 1993, and again on December 7, 1993. The examination of the wreckage revealed that it was scattered over about a 3/4-square mile area with the wreckage distribution oriented on about a 030-to 045-degree magnetic heading. The wreckage was located in a remote portion of the Sierra National Forest, in the John Muir wilderness area.

The left wing was the first portion of the airplane located along the wreckage path. Examination of the wing revealed that it separated from the fuselage at the root end. The upper inboard end of the main wing spar had an upward bend that terminated about 6 inches inboard from the wing skin. The fracture exhibited multiple 45-degree angle surfaces. The upper channel of the spar doubler was bent slightly in an aft direction. The bottom inboard end of the wing spar displayed similar fracture surface signatures, as did that of the spar web. The wing was located with the leading edge down in a clear area at the base of a ridgeline and displayed spanwise aft crushing to the lower side of the leading edge. The aileron and flap assembly remained attached to the wing. The flap actuator was extended 1 and 5/8 inches. According to the manufacturer, the measurement corresponds to a flap up setting. The left main landing gear was retracted.

The empennage was located about 1,100 feet southeast of the wing on a ridgeline, having come to rest after crushing a small tree. The tree was broken in a downward direction and nearby tall trees did not have any broken branches. This portion of wreckage consisted of the upper roof section from the windshield aft to the tail; left and right vertical sides of the airplane; the stabilizers and tail cone. The floor portion of the airplane was missing. The bottom edge of the sides of the airplane that would mate to the floor section displayed shearing of the rivets and adjacent skin.

The tail cone at the forward stabilizer bulkhead was torn open along the bottom edge of the fuselage. The tail was folded upward and bent about 90 degrees to the right. The forward stabilizer bulkhead exhibited tearing at the left stabilizer spar attach fitting rivets.

The left stabilizer was lying parallel to the fuselage and separated from the fuselage at the leading edge cuff. It exhibited diagonal upward and aft curling of the outboard leading edge; however, remained attached to the fuselage at the front and rear spar attach points. The left elevator was attached to the stabilizer and was fractured in a chordwise direction about mid-span, just outboard of the left trim tab. The left trim tab remained attached to the elevator. The trim actuator was extended 1 and 1/4 inches. According to the manufacturer, this corresponds to about a 10 degree tab up (nose-down) setting. The outboard end of the elevator, in which the balance weight is installed, was torn away and missing.

The right stabilizer separated from the fuselage at the leading edge cuff and its spar attach points. The fractured end of the forward spar exhibited aft bending. The stabilizer was lying on top of the empennage, parallel to the fuselage, and next to the left stabilizer. The elevator remained attached to the stabilizer at the inboard end; however, was separated about mid-span in a chordwise direction. The outboard half of the elevator, along with its balance weight, was not located. The trim tab remained attached to the inboard end of the elevator. The left elevator pitch horn remained attached to the elevator; however, separated from the fuselage at the push pull tube. All of the separated surfaces exhibited multiple 45-degree fracture surfaces.

Bulbs from the rotating beacon mounted on the top of the fuselage exhibited unbroken and tightly coiled bulb filaments. The filament from the fuselage rear position light bulb was broken from its support posts. The filament was tightly coiled.

The bottom floor section of the airplane, from the rear wing carry-through to the tail, was located about 800 feet north- northeast of the empennage. The rear seats remained attached to their respective seat rails. The left side of the wing carry- through structure was separated about 6 inches outboard from the fuselage. The fractures exhibited multiple 45-degree fracture surfaces and forward bending. The right side of the wing carry-through separated just outboard from the fuselage. It exhibited similar 45-degree fracture surfaces and forward bending. There were only four seats installed in the airplane. Portions of the trim pulley mechanism and vacuum housings for the autopilot system remained attached to the floor, aft of the baggage area bulkhead.

The engine, attached to the firewall and instrument panel, engine cowling, and right front door, was located about 1,000 feet north of the empennage on the north side of a small creek. It was located standing vertical in a large rock crevice with the instrument panel crushed under the engine. The forward end of the engine case was fractured aft to about the number four cylinder, exposing the crankshaft and camshaft. The number five cylinder head was separated from the cylinder barrel. The number six cylinder was broken away from the case.

The magnetos were both broken away from the engine case. The vacuum pump housing was separated from the case. The internal block and vanes were shattered. Examination of the fuel manifold revealed that the diaphragm was intact and the fuel screen was free of contaminants. Removal of the top spark plugs from the number four and six cylinders revealed no unusual combustion signatures.

The propellers were broken away from the crankshaft and were located about 30 yards north of the engine. They were separated from the hub. One blade exhibited double "S" bending without any obvious torsional twist. The leading edge had heavy gouging and the face side of the blade also exhibited deep diagonal gouges. The second propeller blade was straight. It had trailing edge deformation and cracking about 12 inches inboard from the tip and did not exhibit any torsional twist.

Examination of the visible portions of the instrument panel revealed that the recording tachometer indicated 591.51 hours. The directional gyro indicated a heading of 030 degrees. The attitude instrument housing was shattered; however, the gyro housing was located without the rotor. The interior surface of the gyro housing exhibited rotational scoring. The airplane is equipped with a throw-over style control yoke. The yoke control arm was fractured at the base of the pivot at the instrument panel and at the control yoke attach point. Due to the damage, the position of the yoke was not determined.

The nose gear was located about 90 feet east of the engine. The right main landing gear separated from the wing and was located about 750 feet south of the engine. An oxygen bottle was located near the propellers. The valve of the bottle was in the open position.

Baggage and interior items of the airplane were located along the wreckage path. The front seats of the airplane were located about 900 feet northeast of the rear floor section. The right side cargo door was not located. The right wing of the airplane was not located.

Medical and Pathological Information

A postmortem examination of all occupants was conducted by the Fresno County Coroner's Office, 760 W. Nielson Ave., Fresno, California, 93706, on November 18, 1993. The cause of death for all occupants was attributed to multiple injuries due to blunt impact. No preexisting conditions were noted during the examination which would have adversely affected the decedents abilities to pilot an aircraft.

A toxicological examination of the first pilot was conducted by the FAA Civil Aeromedical Institute (CAMI) on February 28, 1994. The examination was negative for all screened drugs and alcohol.

Tests and Research

A recorded radar data and trajectory study of NTAP data obtained from the ARTCC, Oakland, California, was conducted by the Safety Board's Office of Research and Engineering. The trajectory study indicated the right wing of the airplane to be in a probability area surrounding the left wing's final position, extending 0.11 nautical miles to the east, 0.08 mile to the west, 0.15 mile to the north, and 0.14 mile to the south.

Calculations were based on radar data, winds aloft data, wreckage scatter diagrams, and the performance properties of the airplane's components. A close match for the trajectory paths of the separated components was accomplished when using a breakup altitude of 14,000 feet msl.

Additional Information

The FAA Aviation Weather publication AC 00-6A, pages 83-85, describes mountain wave activity that is generated by wind crossing a mountain barrier. AC 00-6A states in part:

..."Wind flow across the barrier is laminar-that is, it tends to flow in layers. The barrier may set up waves in these layers much as waves develop on a disturbed water surface. The waves remain stationary while the wind blows rapidly through them...The wave pattern may extend 100 miles or more downwind from the barrier...Updrafts and downdrafts in the waves can also create violent turbulence...Crests of the standing waves may be marked by stationary, lens-shaped clouds known as 'standing lenticular' clouds."

The airplane wreckage has not been recovered and the National Transportation Safety Board did not take custody of any portion of the airplane.

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