Aviation Accident Summaries

Aviation Accident Summary LAX01FA001

SAN JUAN BATIST, CA, USA

Aircraft #1

N36TV

Beech A36TC

Analysis

The airplane collided with mountainous/hilly terrain as the pilot descended in instrument conditions toward the destination airport. The non-instrument rated pilot was obtaining VFR flight advisories from Air Traffic Control, and told approach control that he intended to head for his destination in visual conditions. A few minutes later the pilot stated that he intended to circle down through a hole. At this time, approach lost radar contact at a mode C reported altitude of 3,500 feet on a southeasterly track in an area of hilly terrain where it is not uncommon to loose radar contact at that altitude or less. The controller assumed that he was losing the radar contact, terminated radar service, and approved a frequency change. The controller did not hear a response from the airplane. At 2009:29, the target was at a mode C reported altitude of 2,200 feet. By 2011:03, the target had turned left on a southwesterly track and was at a mode C reported altitude of 1,300 feet. This was the last recorded target for the flight's assigned secondary beacon code. The accident site elevation was about 1,000 feet. A resident who lived near the accident site reported that it was very foggy about the time of the accident, and estimated that the visibility was 100 feet..

Factual Information

HISTORY OF FLIGHT On October 1, 2000, about 2010 Pacific daylight time, a Beech A36TC, N36TV, collided with mountainous/hilly terrain near San Juan Bautista, California. The pilot/owner was operating airplane under the provisions of 14 CFR Part 91. The private pilot and three passengers sustained fatal injuries. The airplane was destroyed. The personal cross-country flight departed Mammoth Lakes, California, about 1845, en route to Watsonville, California. Visual meteorological conditions prevailed at Salinas, California, the nearest reporting station, which was 11 miles from the accident site. Witnesses in the area of the accident site reported that instrument meteorological conditions consisting of coastal low clouds and fog prevailed at the accident site. No flight plan had been filed. The primary wreckage was at 36 degrees 49.702 minutes north latitude and 121 degrees 34.59 minutes west longitude. The pilot and three friends flew from Watsonville to Mammoth Lakes in the morning with the return trip scheduled for that afternoon. About 1730, one of the passengers called a family member to inform them that the return would be delayed. The passenger said that the flight should be about 1 1/2 hours long, and they would not arrive until 2130. The Federal Aviation Administration (FAA) submitted a summary of recorded radio transmissions between air traffic control facilities and N36TV. The pilot checked in with Oakland Air Route Traffic Control Center when he was 20 miles west of Mammoth Lakes at 14,000 feet and requested flight following. Oakland identified the airplane and provided a discreet secondary beacon code of 3354. Eventually, control passed to Monterrey Approach Control (SECA). At 2002:53, the pilot reported that he was leaving 8,000 feet for 4,500 feet. He stated that his intensions were to head for Watsonville in visual conditions. The National Transportation Safety Board investigator-in-charge (IIC) reviewed recorded radar data. A target with the secondary beacon code of 3354 maintained a southwesterly descent. At 2004:32, the target was at a mode C reported altitude of 7,400 feet and began a turn to the southeast. It maintained the southeasterly track and continued to descend. At 2005:11, the pilot stated that he intended to circle down through a hole. He requested that SECA provide him the frequency for the Watsonville ASOS (Automated Surface Observation System). The transmission was not clear, and it took several attempts for the controller to understand and comply with the request. The pilot acknowledged the frequency at 2008:03, and the transcript indicated that there was no other contact with the airplane. At this time, the radar contact was at a mode C reported altitude of 3,500 feet, and maintaining a southeasterly track. At 2008:58, the Monterey local controller contacted SECA to assume the approach control duties. SECA stated that N36TV was the only airplane that the local controller would be talking to, and it was maneuvering north of Salinas en route to Watsonville. The local controller mentioned that at first he thought the airplane was going southeast, but now it was going northeast. As the two controllers discussed N36TV, SECA pointed out that the airplane had been at 6,500 feet. SECA mentioned that the local controller would lose the radar target as the airplane descended and might consider terminating radar services. At 2009:52, the controllers noticed that the target went into coast mode. The local controller broadcast to N36TV that he was losing the radar contact. The local controller terminated radar service and approved a frequency change. The controller did not hear a response from the airplane. At 2009:29, the target was at a mode C reported altitude of 2,200 feet. By 2011:03, the target had turned left on a southwesterly track, and was at a mode C reported altitude of 1,300 feet. This was the last recorded target for secondary beacon code 3354. The main wreckage was at an estimated elevation of 1,000 feet. PERSONNEL INFORMATION A review of FAA airman records revealed the pilot held a private pilot certificate with an airplane single-engine land rating. The pilot held a third class medical certificate that was issued on April 13, 1999. It had the limitations that the pilot must wear lenses for distant vision and possess glasses for near vision. The pilot's logbook was not recovered. A review of FAA records revealed that the pilot did not possess an instrument rating. AIRCRAFT INFORMATION The airplane was a Beech A36TC, serial number EA-33. The airplane's logbooks were not recovered. A work order from a maintenance facility revealed a total airframe time of 3,524 hours at the last annual inspection. The work order indicated that the maintenance facility completed an annual inspection on July 14, 2000. Another work order for an oil change dated August 11, 2000, indicated a tachometer time of 3,541 hours. The airplane's engine was a Teledyne Continental Motors TSIO-520-UB, serial number 809371-R. A maintenance facility installed a factory-rebuilt engine at the annual inspection. Fueling records at Hot Creek Aviation, Mammoth Lakes, established that the airplane was last fueled at 1746 on October 1, with the addition of 21.8 gallons of 100-octane aviation fuel. METEOROLOGICAL INFORMATION Residents who lived within 1 mile of the accident site reported that it was very foggy about the time of the accident. One resident estimated that the visibility was 100 feet. He said the fog persisted into the next morning and everything was soggy. The closest official weather observation station was Salinas (SNS). The elevation of the weather observation station was 84 feet msl. An aviation routine weather report (METAR) issued at 1953 reported: skies overcast at 500 feet; fog; visibility 5 miles; winds 320 degrees at 8 knots; temperature 61 degrees Fahrenheit; dew point 59 degrees Fahrenheit; and altimeter 29.92 inHg. A METAR issued at 1953 for Watsonville, the destination airport, reported: skies overcast at 200 feet; fog; visibility 3 miles; winds 270 degrees at 4 knots; temperature 59 degrees Fahrenheit; dew point 59 degrees Fahrenheit; and altimeter 29.93 inHg. Safety Board software determined that Watsonville was 12 miles from the accident site on a magnetic bearing of 285 degrees. Salinas was 11 miles from the accident site on a magnetic bearing of 171 degrees. Safety Board software determined that sunset occurred at 1851, and there was 19 percent illumination of the moon. COMMUNICATIONS The airplane was in contact with Monterey Approach Control on frequency 133.00, with no communications difficulties reported by ATC. WRECKAGE AND IMPACT INFORMATION The accident site was in rolling hills with scattered clusters of trees. The main wreckage was on a 45-degree upslope. The debris path began midway up a ridgeline, and continued up hill. The debris path was along a magnetic bearing of 300 degrees, and the upslope shallowed to 5 degrees within 10 feet of the main wreckage. The fuselage came to rest on a heading of 250 degrees. The empennage was along a heading of 210 degrees. An inverted U-shaped burn area began at the main wreckage. An area of burned grasses and bushes extended about 60 feet forward of the main wreckage. It fanned out about 60 feet to the left and 30 feet to the right of the debris path centerline. A 10-foot-wide burn area at the most forward part of the burn area continued 90 degrees to the right and widened to 25 feet. After about 80 feet, it turned 90 degrees to the right, and fanned out as it went back downslope about 60 feet. The engine separated and was a few feet in front of the main wreckage. The exhaust tubes were crushed and buckled, but not cracked. The propeller blades separated and were several feet forward of the hub. The central shaft of the propeller and the spring surrounding it bent down about 90 degrees. One blade had dents along the trailing edge. The tip of the second blade curled aft about 180 degrees, and the blade twisted toward the low pitch position. The third blade twisted toward the low pitch position. Two seats, one at 10 feet and the other at 25 feet, were forward of the main wreckage along the centerline of the debris path. The seats were in the burn area and all that remained of them was the frames. About 10 feet right of the second seat was the burned entry door's frame. A piece of fuselage skin was the last discovered piece of wreckage. This skin piece was 105 feet from the main wreckage on the debris path centerline. It was outside of the burned area, and its paint was not scorched. Fire consumed the cabin, the inboard portions of both wings, and the fuselage from the cockpit to the leading edge of the vertical stabilizer. Both wings had aft leading edge crush damage. Plexiglas and objects outside of the burn area were not scorched, sooty, or melted. The left aileron and flap remained attached to the left wing. The aileron push rod was attached to the aileron and aileron bellcrank. The aileron cables remained attached to the bellcrank. The right wing separated outboard of the attach bolt. About 7 feet of the right wing separated and was 75 feet from the main wreckage at the 3-o'clock position. This section exhibited aft crush damage to the leading edge. This piece was in the unburned portion of the U-shaped burn area, and only the inboard edge burned. The aileron remained attached to this segment. The aileron cable separated in a broomstraw pattern. The empennage stayed together. The rudder remained attached to the vertical stabilizer. The right side of the vertical stabilizer burned and fire consumed the lower section of the right side of it. Both rudder cables remained attached to the rudder bellcrank. Both elevator push rods remained attached to the elevator torque tubes. Fire consumed the majority of the forward portion of the right horizontal stabilizer, most of its bottom skin, and most of the elevator's bottom skin. The outboard 3-feet of the right horizontal stabilizer separated from the inboard portion along a jagged edge and lay several feet away. The left horizontal stabilizer and elevator remained in place, but sustained some mechanical damage. The majority of the separated pieces were in the burn area and exhibited severe thermal damage. MEDICAL AND PATHOLOGICAL INFORMATION The San Benito County Coroner completed an autopsy. The FAA Toxicology and Accident Research Laboratory performed toxicological testing of specimens of the pilot. The results of analysis of the specimens were negative for carbon monoxide, cyanide, and tested drugs. The report contained the following positive results: 18 (mg/dL, mg/hg) ethanol detected in muscle; 77 (mg/dL, mg/hg) ethanol detected in kidney; 21 (mg/dL, mg/hg) acetaldehyde detected in kidney;14 (mg/dL, mg/hg) N-propanol detected in kidney. TESTS AND RESEARCH Investigators from the Safety Board, the FAA, Beech, and Teledyne Continental Motors (TCM) examined the wreckage at Plain Parts, Sacramento, California, on October 17, 2000. The recovery agent removed the engine, and shipped it to TCM, Mobile, Alabama, for examination. TCM personnel examined it under the supervision of a Safety Board investigator on October 25, 2000. TCM submitted a written report. The report noted that the engine exhibited extensive post impact fire and mechanical damage. The internal components appeared normal, except for dark areas and burned oil, which they felt were due to a post accident fire. Several thru bolt nuts were broken and split. A metallurgist from TCM determined that heat from melting cadmium plating caused embrittlement, which resulted in the bolt fractures. TCM felt that the engine did not exhibit any condition that could have caused an operational problem prior to the accident. The fuel selector valve was in the left main tank position. The left flap actuator was measured at 1.75 inches. The right actuator was consumed by postimpact fire. This corresponded to the full up position. Both elevator trim actuators measured 1.06 inches. This equated to 8 degrees tab up. The main landing gear motor and gearbox were destroyed, and the representative was unable to determine the landing gear position. ADDITIONAL INFORMATION A Safety Board specialist interviewed the controllers. Both controllers said that they would normally expect to lose radio and radar contact in the area where N36TV was last seen. The SECA controller said that the track was consistent, and there were no intermittent targets prior to the loss of contact. He thought that the airplane showed altitude information until he lost the target. He said the normal procedure with unexpected loss of a target would be to notify a supervisor and provide the location. Since he expected to lose the target, he did not notify his supervisor. He said that there was no requirement for controllers to obtain weather data for airports other than Monterey unless the pilot requested it. Pilots are normally instructed to monitor the ASOS broadcast directly. The Monterey local controller informed the Safety Board specialist that there were no MSAW (minimum safe altitude warning) activations because MSAW was inhibited for VFR flights. The IIC released the wreckage to the owner's representative.

Probable Cause and Findings

the pilot's in-flight decision to continue flight into instrument weather conditions at an altitude that did not maintain an adequate terrain clearance, which resulted in a collision with terrain. Factors were a dark night, clouds, fog, mountainous terrain, and lack of instrument rating.

 

Source: NTSB Aviation Accident Database

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