NTSB Factual Report

HISTORY OF FLIGHT

On December 5, 1994, about 1853 Pacific standard time, a Piper PA-28R-180, N4510J, was destroyed after striking trees on a ridge line while descending near Groveland, California. The aircraft was owned and operated by a partnership and was on a personal cross-country flight. Intermittent instrument meteorological conditions had been reported at the destination and no flight plan had been filed. The certificated commercial pilot and his passenger, a certificated private pilot, sustained fatal injuries. The flight was cleared for departure from the San Jose International airport at 1715 on the day of the accident.

There were no eyewitnesses to the accident. The accident time was estimated based upon a review of recorded radar data and records of the pilot's cellular telephone use.

The straight line distance between the departure point and the destination airport was measured as 104 statute miles along a 050-degree magnetic course. The aircraft manufacturer estimated that the cruise speed of the aircraft was at 75 percent power and with a density altitude of 5,500 feet to be approximately 157 mph. Adding 10 minutes for departure climb, the estimated time en route under "no wind" conditions was approximately 50 minutes. The time between departure clearance and the estimated time of the crash was 1 hour 38 minutes. No record was found that the aircraft communicated with any aeronautical ground station. According to the Civil Air Patrol, no evidence was found that the aircraft landed at any airport along the projected ground track.

Recorded radar data was obtained from the Oakland Air Route Traffic Control Center. For the estimated time and location of the accident site, a secondary beacon target with a Mode C report was observed. The beacon return disappeared at the estimated accident time about 1,600 feet from the crash site. No other targets were observed in the vicinity during this time frame. A review of radar data beginning at 1842:06 in the vicinity of the Pine Mountain Lake airport revealed that the target maintained a relatively constant northeasterly heading on a course that would pass approximately 3.5 miles northwest of the airport.

Detailed review of the data failed to reveal any sustained changes in heading during the last 10 minutes 36 seconds of the track. According to the radar data, the aircraft began a descent from approximately 5,700 feet about 1844:54. The last radar return at 1852:42 showed the aircraft had descended to 3,800 feet msl.

A witness at the Pine Mountain Lake airport stated that weather had been "up and down" all day as low cloud layers moved through the area. At the approximate time of the accident, he recalled seeing the activation of the visual approach slope indicator (VASI), and runway lights were illuminated. The witness did not recall seeing or hearing an aircraft at the time of the reported time of the crash and was also uncertain of the specific sky condition. He further stated that when weather does not permit landing at Pine Mountain Lake, a common procedure is to proceed to either Columbia or Oakdale airports. He also stated that there are very few ground lights in the area of the crash and that based on his experience it would be difficult to see the surrounding terrain on a dark night. At the estimated time of the crash, astronomical twilight had expired and the sun was 24.5 degrees below the horizon.

PERSONNEL INFORMATION

According to friends of the pilot who were interviewed, he was familiar with the route flown. He had lived in the Groveland area for approximately 5 years and routinely flew the same route back and forth during the week to his job in San Jose, California.

Friends of the pilot reported that he had voiced serious concern over ongoing marital and financial difficulties.

AIRCRAFT INFORMATION

According to fueling records at ACM Aviation at the San Jose International airport, the pilot purchased 22.5 gallons of 100 octane low lead aviation fuel on the day of the accident.

During the last annual inspection of the aircraft, the condition of the pitot heat was entered in the aircraft logbook as inoperative. There was also an entry stating that the pitot static system inspection was overdue.

METEOROLOGICAL CONDITIONS

According to Federal Aviation Administration (FAA) records of weather briefings given, the pilot, by name, connected on the DUAT system between 1555 and 1556 on the day of the accident. System records disclosed that the pilot asked for selected surface observations from the following California airports: Crows Landing, Modesto, Stockton, Livermore, and San Jose.

Columbia airport aviation weather observation service (AWOS) at 1700 was reporting 600 feet overcast with 15 miles visibility. A pilot who landed at the Pine Mountain Lake airport about 1900 on the evening of the accident reported the weather as: ceiling 1,500 feet; visibility 20 miles; winds variable, but predominantly from the north with broken cloud formations moving through the area at 600 to 800 feet.

COMMUNICATIONS

A witness, who lives on the Pine Mountain Lake airport, reported that about 1730 his wife received a telephone call from the pilot. At that time, the pilot stated that he was en route "over the valley" and was calling to check the weather at his destination. The witness said that he and his wife had left home about 15 minutes prior to the estimated accident time. The first witness reported being told that another pilot on the airport heard a radio transmission on 123.05, the CTAF frequency, at about the accident time. The transmission reportedly consisted of, "Hugh (the name of the second witness), do you have your radio on?"

A cellular telephone was located at the crash site, which was subsequently identified as belonging to the pilot. GTE Mobilnet was identified as the service provider for the telephone. According to company records, there were 13 cellular telephone calls attempted between 1731 and the time of the accident. Of those calls, three were attempted during the last 10 minutes of the flight, with one call nearly coinciding with the estimated time of the crash. On two occasions, the number called on the cellular phone was the same number as that assigned to the phone being used to make the call. No other cellular telephones were found at the crash site.

WRECKAGE AND IMPACT INFORMATION

The first identified impact point was noted to be two pine trees, located on the crest of a ridge line, which were sheared off at approximately 40 feet above their base. The first tree was struck at a point which was approximately 4 inches in diameter while the second tree was struck at a point which was approximately 7 inches in diameter. A section of web from the left wing was found at the base of the trees.

The wreckage distribution was along a 020-degree path that measured approximately 614 feet from the initial tree strike to an initial ground scar located on a 30-degree slope, about 60 feet below the ridge line. Along that path were found a section of the left wing with the stall-warner, a portion of the left wing flap, a fiberglass wing tip, a portion of engine cowling, fragments of clear Plexiglas, and a cellular telephone. Also found were several 1-inch-diameter sections of pine bows which exhibited a series of clean 45-degree cuts.

The propeller and hub had separated from the engine and were located in the initial ground scar. Both blades exhibited gouges on their leading edges. One blade exhibited a torsional twist.

From the initial ground impact point, a path of ground scars and vegetation disturbance was observed over a distance of 74 feet of down-sloping terrain, on a bearing of 340 degrees. The aircraft was located at the end of the ground disturbance on a forest service access road. Both front seats were found displaced and separated from the aircraft.

MEDICAL AND PATHOLOGICAL INFORMATION

An autopsy was performed on the pilot by the Tuolumne County Coroner's Office with specimens retained for toxicological examination. The results of the toxicological tests were negative for alcohol and all screened drugs with the exception of acetaminophen and salicylamide.

ADDITIONAL INFORMATION

An emergency locator transmitter (ELT) beacon was installed in the aircraft. Initially, search and rescue personnel did not report receiving an ELT signal; however, after locating the wreckage, ground search and rescue units near the accident site reported receiving an ELT signal. The ELT was found in the wreckage with its switch in the armed position. The coaxial cable between the ELT and its antenna was found to have separated.

The aircraft wreckage was recovered from the accident site and secured in an aircraft storage facility. The wreckage was released to a representative of the registered owner on January 27, 1995. Three components -- the vacuum pump, directional gyro, and artificial horizon -- were returned to a representative of the storage facility on March 16, 1995.

NTSB Probable Cause

the failure of the pilot to maintain adequate terrain clearance during a nighttime descent into the airport over an unlighted mountainous area. Contributing to the accident was the pilot's distraction by attempting to make several cellular telephone calls during a critical phase of flight.