Introduction
On February 19, 2010, at 1917 Pacific standard time, a Piper PA-32R-301T, registration N4175A, collided with terrain in a residential area near Groveland, California. The pilot operated the airplane under 14 CFR Part 91. The certificated private pilot and passenger were killed. The airplane sustained substantial damage from impact forces, and the fuselage was consumed in a post-crash fire. The cross-country personal flight departed San Carlos Airport, California, about 1825, with a planned destination of Pine Mountain Lake Airport, Groveland. Night instrument meteorological conditions prevailed at the accident site, and no flight plan had been filed.
Flight History
A witness in a north-facing room directly adjacent to the accident site heard a sound that appeared to emanate directly above his house, similar to an engine running at full power. He looked out the window and a few seconds later observed an explosion about 300 feet to the northeast in his neighbor’s yard. He reported light rain and mist at the time of the accident.
A second witness, located 1/2 mile northeast of the approach end of runway 27, heard a low-flying airplane that he presumed was flying directly over his house, with an engine running “full bore.” He ran onto his deck and a few seconds later observed a fireball erupt in the valley below. He reported that the airport beacon was partially obscured by mist and that the explosion area was enveloped with clouds.
First responders and additional witnesses reported similar weather conditions: light rain, mist, and low clouds.
A pilot who flies to the airport most weekends reported attempting to land a Cessna 510 on an instrument flight plan about 1 hour prior to the accident. Throughout the instrument approach, he was unable to identify the runway environment and performed a missed approach, diverting to Modesto where he landed uneventfully. He reported that this was the first time he needed to divert.
The pilot was receiving flight following services for the initial en route portion. Radar and voice communication data showed the target departing San Carlos with a 4530 beacon code, tracking northeast at 5,500 feet msl. At 1845, the pilot established communication with Northern California Terminal Radar Approach Control, stating he was “level 5,500 for Pine Mountain Lake.” The controller provided an altimeter setting for Stockton.
The target continued at 5,400 feet for 25 minutes. The pilot reported, “Saratoga 4175A, we still don't have Pine Mountain and Lake, but we are going to switch over.” The controller approved a frequency change and requested squawk VFR. The pilot responded, “We may come back to you if it's fogged in over at Pine Mountain.” This was the last recorded communication.
At 19:10:54, 12 miles southwest of the airport, the 4350 code radar target disappeared and was replaced by a target on 1200 code. Over the next 3 1/2 minutes, the target descended to 4,000 feet on a heading of about 045 degrees. As it approached within 4 miles of the airport, it made a right turn to about 090 degrees, in line with runway 090, then overflew the airport at 4,000 feet. For 30 seconds, the target changed heading to the northeast, maintaining altitude, then climbed to 4,500 feet. The next radar return appeared 20 seconds later, 1,000 feet lower and 3/4 mile south. Over the next 60 seconds, the target oscillated between 3,500 and 4,600 feet and headings between 205 and 340 degrees. The final radar return was at 3,600 feet, 800 feet south of the accident site.
Personnel Information
The 70-year-old pilot held a private pilot certificate with ratings for airplane single-engine land and instrument airplane. He held a third-class medical certificate issued September 2008, with a limitation to wear corrective lenses.
His logbook showed a total flight experience of 1,083 hours since July 2000, with 443 hours in the accident airplane make and model, 17 of which in the 90 days prior. He reported 173.4 hours of simulated instrument time and 37.4 hours of actual instrument time, with 1.7 in the previous 6 months and two instrument approaches during that period. He had 31.7 hours of night flight experience, 2.4 of which were into Pine Mountain Lake. He had never performed an approach into Pine Mountain Lake in actual instrument conditions.
In 2007, the pilot was involved in an accident in N4175A while landing at Pine Mountain Lake; the NTSB probable cause was “The pilot's inadequate compensation for the gusty, crosswind and downdraft wind condition, which resulted in a hard landing.”
Aircraft Information
The low-wing, retractable-gear airplane was manufactured in 2000, powered by a six-cylinder Textron Lycoming turbocharged TIO-540 engine with a Hartzell three-blade constant-speed propeller.
An annual inspection was completed on May 9, 2009, at 1,310 flight hours. The most recent logbook entry, dated February 5, 2010, documented maintenance to the landing gear system at 1,395.7 hours. The altimeter and encoding systems were tested and inspected in April 2008, as were the transponder systems.
The airplane was equipped with navigational and flight instruments for IMC, including Garmin 430W and 530W WAAS GPS/Nav/Comm transceivers and a Garmin GDL-49 satellite data link transceiver. An impact- and fire-damaged Garmin GPSMAP696 portable GPS was found in the cabin wreckage.
According to the original equipment list, the airplane had an STEC-System 55 autopilot (with HSI). The airframe logbooks showed no recent maintenance on navigation or autopilot systems.
Meteorological Information
The FAA had no record of a pilot preflight weather briefing or DUATS access for the flight. The pilot’s office computer showed last weather website access on February 16, three days prior.
An AWOS-3 at Columbia Airport (16 NM northwest, elevation 2,118 feet) registered two minutes before the accident: calm winds, 1 mile visibility, overcast 300 feet, temperature 9°C, dew point 8°C, altimeter 29.83 inHg.
A METAR at Merced Castle Airport (34 NM southwest) 32 minutes prior: winds 020° at 3 knots, 10 miles visibility, broken 2,500 feet, overcast 5,000 feet, temperature and dew point 13°C, altimeter 29.83 inHg.
An AIRMET SIERRA for mountain obscuration was issued for the accident location at 1242 and 1833 that day.
NEXRAD base reflectivity at 1917 indicated precipitation near Pine Mountain Lake Airport.
A webcam image at 1745 showed fog and mist enveloping the runway environment, with hills 3 miles away partially obscured by clouds.
Sunset in Sonora was at 1745, civil twilight ending at 1811. A NOTAM for Stockton Metropolitan Airport reported the Terminal Area Weather Surveillance Radar out of service since May 28, 2009.
Airport Information
Pine Mountain Lake Airport is in the western foothills of the Southern Sierra Nevada, adjacent to the Stanislaus National Forest. The airport elevation is 2,933 feet, with a single asphalt 09/27 runway 3,624 feet long. It has a VASI for runway 9, PAPI for runway 27, and a lighted tetrahedron.
Examination two days after the accident revealed no failed lamps; runway lights illuminated when commanded on CTAF.
The airport had two instrument approaches: RNAV (GPS) Rwy 09 and GPS Rwy 27. It was uncontrolled, using CTAF, with no official weather observation station.
Wreckage and Impact Information
The airplane came to rest in a residential area about 1,200 feet north and 50 feet below the approach end of runway 27. First impact was a 30-foot-wide near-vertical swath through branches of a 50-foot-tall tree. A shattered wooden fence was at the base of the tree. Fragments of the right wing tip, green navigation light lens, and angularly cut wood were found at the fence. A 25-foot-long ground indentation continued on a heading of about 035 degrees, leading to a crater 18 feet long, 10 feet wide, and 4 feet deep, oriented on 060 degrees. Fragments of the right wing, cabin belly stringers, and a propeller blade were in the crater. The blade had leading edge nicks and a separated tip with jagged fracture. The tree and surrounding area contained fragmented wing and fuselage spar and skins, right flap, and right aileron. The debris field continued on a 060-degree heading for 120 feet to the main wreckage.
The main wreckage included the cabin, empennage, and engine. The cabin structure was heavily fragmented, crushed, and consumed by fire. The tailcone had heavy crush damage; the empennage remained partially attached, crushed and twisted. Remaining wing sections were fragmented and strewn throughout the debris field.
The engine remained partially attached to the firewall without fire damage. The two attached propeller blades had leading edge gouges and tip twist.
No evidence of in-flight fire was found. All major sections were accounted for. Fuel odor was present. No evidence of additional prior contact with trees or obstructions was found.
Medical and Pathological Information
An autopsy by the Tuolumne County Coroner reported the cause of death as multiple traumatic injuries.
Toxicological testing by the FAA Bioaeronautical Sciences Research Laboratory was negative for all screened drug substances and ingested alcohol.
Tests and Research
The engine and airframe were examined on site and removed for further examination. The top spark plugs showed no mechanical damage; electrodes and posts had light grey deposits consistent with normal operation. Borescope inspection of combustion chambers revealed no foreign object damage or detonation, with light grey deposits consistent with normal operation.
The airspeed indicator was impact-damaged; a needle-shaped scratch and transfer mark at the 200-knot position was noted.
Impact damage and post-crash fire prevented determination of the operational status of flight instruments or autopilot. Examination of remaining wreckage revealed no evidence of pre-mishap mechanical malfunctions.