On September 18, 1999, about 1300 hours Pacific daylight time, a Piper PA-24-180, N5673P, collided with mountainous terrain on Mount Gibbs near June Lake, California. The airplane, owned and operated by the pilot, was destroyed. The private pilot and his passenger received fatal injuries. The airplane was being operated under the provisions of 14 CFR Part 91 for the personal flight. An IFR flight plan was filed, but never activated. The flight originated at the Petaluma, California, airport between 1030 and 1130 as a cross-country flight to Bryce Canyon, Utah.

When family members failed to hear from the pilot or passenger by September 20, they reported the airplane missing. An ALNOT was issued by the Federal Aviation Administration (FAA), and search efforts were begun by the California Wing of the Civil Air Patrol (CAP). In subsequent coordination discussions, the CAP verbally told Safety Board investigators that the pilot departed Petaluma airport about 1030, did not file a flight plan, and did not talk with Air Traffic Control. They were unable to find any recorded radar data that could be connected to the accident airplane, and conducted a wide area airborne search. No Emergency Locator Transmitter (ELT) signals were received or reported by any source from the downed airplane.

Safety Board investigator interviews with family members disclosed that the pilot had indicated he was going to fly from Petaluma to Bryce Canyon. The pilot intended to spend 1 night at the Bryce Canyon Resort, and then he was going to fly to the Santa Fe, New Mexico, area to visit a guest ranch. The family was unclear what his return route of flight was going to be.

A witness who has an airplane in a hangar at the Petaluma airport stated to Safety Board investigators that that it was foggy with low ceilings early in the morning on September 18, and the weather began to clear about 1100 to 1130. He said he watched the pilot takeoff about 1100 to 1130, with nothing unusual about the takeoff that he observed. The witness indicated that the accident airplane took off with a group of "about 4 airplanes" once the weather began to lift.

Based on information found by the family on the pilot's home computer, Safety Board investigators contacted the DUATS contractor. Two contacts were recorded under the pilot's account number, and the DUATS contractor provided the records of those contacts. The first one occurred on September 17 at 1109, and consisted of the pilot filing an IFR flight plan for the trip. The second contact on September 18 at 0603 consisted of a standard weather briefing. Full transcripts of the DUATS sessions are appended to this file.

The flight plan information as entered by the pilot consisted of the airplane's true airspeed of 130 knots, an estimated departure time from the Petaluma airport of 0800, and a requested cruise altitude of 13,000 feet. His route of flight was listed as SGD (Scaggs Island VOR), ECA (Stockton VOR), federal airway V244, ILC, federal airway V293, BCE (Bryce Canyon airport). He stated his destination was Bryce Canyon airport. According to FAA facility records, the flight plan was never activated. The contents of the weather briefing are discussed in the METEOROLOGICAL INFORMATION section of this narrative.

On September 24, 1999, at 1658, the Mono County Sheriff's Department dispatch center received a telephone report of a downed aircraft in the Mono Pass area, northwest of June Lake. The report came from the CAP, who reported the discovery of the single engine fixed low wing airplane. Search and Rescue personnel reached the location and determined the wreckage was the missing airplane. The accident site is on Mt. Gibbs at the 11,760-foot level, and is approximately 25 miles northwest of the Mammoth Lakes Airport. The site is also approximately 2 miles south of the centerline of federal airway V244.


The pilot's Airman and Medical Certification files, maintained by the FAA in Oklahoma City, Oklahoma, were reviewed. According to the files, the pilot held a private pilot certificate with airplane ratings for single engine land, multiengine land, and instruments. The most recent third-class medical certificate was issued on November 2, 1998, with the limitation that correcting lenses for near and distant vision be worn.

A review of the pilot's personal logbook indicates that he had approximately 1,070 hours in single engine land airplanes, 670 hours in a multiengine airplane, and about 1,750 hours of total flight time. He had logged 223 hours of actual instrument time, with the most recent actual instrument flight being in May 1999 for a total of 3.0 hours. The most recent biennial flight review found in the logbook was completed on August 28, 1997, in a Piper PA-18-150.


The airplane was a 1959 Piper PA-24-180. According to the aircraft logbook, the last annual inspection was performed on September 2, 1998, at a recording tach time of 490.6 hours and a total airframe time of 5,994.6 hours. The altimeter/static system was inspected in accordance with 14 CFR 91.411 on June 11, 1998.


As noted in the HISTORY OF FLIGHT section of this narrative, the pilot logged onto the DUATS system at 0603 on the morning of departure, and requested a low altitude weather briefing for the route of flight listed on his IFR flight plan. Transcripts of the briefing session are appended to this file. The San Francisco Area forecast viewed by the pilot was issued at 0345 on September 18, and included flight precautions for coastal IFR conditions and mountain obscuration in the Sierra Nevada Mountains. The area of the accident site was forecast to have scattered clouds to 15,000 feet with light rain showers, becoming scattered thunderstorms with tops to 40,000 feet by 1300. A SIGMET was in effect for scattered thunderstorms over the route, and AIRMET Sierra was valid for coastal IFR conditions and mountain obscuration. The radar summary was showing no echoes.

According to recollections of the Mono County Chief Deputy Coroner, who lives in Mammoth Lakes, it was a cloudy and blustery day. He recalled that there were gusty winds, thunderstorms, and frequent rainsqualls during the day. He estimated that the cloud ceiling was about 10,000 feet. Additionally, he estimated that the winds over the ridge tops and through the mountain passes were in the range of 20-40 miles per hour.

A local sheriff's officer and the airport manager at Mammoth Lakes Airport stated that the weather conditions were rainy and cloudy with thunderstorms in the area most of the day. The officer said he was in the town of Mammoth Lakes, and that there were gusty winds and heavy thunderstorm activity during the afternoon with brief periods where it would quit raining.

Residents of Lee Vining, a community approximately 16 miles north of June Lake and about 4 miles east of the accident site, indicated that the weather was heavy rain "all day" with low clouds and calm winds. A business owner in Lee Vining said that on the 18th, it was raining heavily all day with low clouds. Additionally, the Fire Chief in June Lake indicated that, according to their logs, it was cloudy with rain on the 18th.

The AWOS report for Mammoth Lakes airport was obtained for the accident date. At 0700, the weather was reported to be 5,000 scattered, 7,500 broken, 8,000 overcast with 10 miles visibility. The temperature was reported to be 46 degrees, with a dew point of 41 degrees. At 1200, the weather was reported to be 1,400 scattered, 7,000 broken, 8,000 broken with 10 miles visibility, temperature of 52 degrees, and a dew point of 44 degrees.

A Safety Board staff meteorologist compiled a Meteorological Factual Report. In pertinent part, the meteorologist found that the Surface Analysis chart prepared by the National Weather Service (NWS) for 1100 on September 18, 1999, showed an inverted trough of low pressure over central California. The NCEP 700-millibar (about 10,000 feet) analysis charts for 1700 showed an area of low pressure centered along the California/Nevada border. Upper air plots from Reno, Nevada, indicated that the winds at those levels were from the east-northeast between 10 and 30 knots.

An in-flight advisory, or AIRMET, for instrument flight rules over coastal California and mountain obscuration over portions of southern Nevada and Utah were issued at 0645 by the AWC and pertinent to the airplane's route of flight.

Satellite data was obtained from the Geostationary Operational Environmental Satellite-10 with maps of Sacramento, Fresno, Hanford Weather Surveillance Radar, Doppler, and the accident location were overlaid on the images. Looping of the visible satellite imagery between 1215 and 1315 revealed that an upper level low-pressure center was located in vicinity of the California-Nevada border just north of the accident location.

Radar data was reviewed with reflectivity's with intensities of 0-15 dBZs near the V244 radial from 15 nautical miles east of the Ducke Intersection until near the accident location.

Reno is the closest upper air meteorological observation station to the accident site, and it is 105 miles northwest of the accident site. Review of the upper air data show nearly saturated conditions between 9,000 and 23,700 feet, with east northeasterly winds less than 15 knots and a freezing level just above 12,000 feet.

Pilot reports during the morning and early afternoon indicated that there were cloud bases of 10,000 to 12,000 feet over the Sierra Nevada Mountains.

Another pilot, who said he was flying the day of the accident, came forward with additional information regarding the weather near the crash site. He said he departed Glendale, Arizona, at 0430 for an IFR flight to Seattle, Washington. He said his route of flight was along federal airway V105 at 14,000 feet mean sea level. He said that he recalled encountering actual instrument meteorological conditions just before Las Vegas, Nevada, and thought they broke out into visual meteorological conditions after the Coaldale VOR. He also said that at the Yerin intersection, which is north of the accident site, he canceled his IFR clearance and preceded VFR to South Lake Tahoe, California.


The accident site is at 11,760 feet on the southwest face of Mount Gibbs at coordinates north 37 degrees 51.769 minutes by west 119 degrees 12.694 minutes. The angle of the slope was between 25 and 30 degrees, with a surface composed of loose, fractured shale and slate rock. The Chief Deputy Coroner told Safety Board investigators that the crash site was extremely unstable and that he felt there was extreme danger of the airplane sliding down the slope.

The nose of the airplane was facing southwest, and the search and rescue personnel estimated the wreckage to be approximately 1/4 mile from the top of the mountain. NAS Fallon helicopter crews estimated the summit to be approximately 12,700 feet in elevation.

The nose crush angle was measured at 35 degrees, with similar leading edge accordioning crush to the entire span of the left wing. Aileron, rudder, and horizontal stabilizer control continuity was established from the cockpit controls to the respective control surfaces.

The ELT remained secured in its mount in the empennage. The switch was found in the "off" position; the unit tested satisfactorily when manually activated.

Unbroken light bulbs were recovered from various locations within the interior of the cabin and examined for filament stretch. The filaments for the low vacuum, low oil, and low voltage bulbs were all normal in appearance. Filament stretch and elongation were found on several instrument post lights.

The fuel selector was found to be slightly off the left tank detent. Both fuel bladder tanks were ruptured and there was no residual fuel found in either fuel cell. The propeller, mixture, and throttle were full forward. The carburetor heat was found in the full cold position. The magneto switch was set to both. The audio panel was destroyed in the impact sequence.

Cloth bags to hold oxygen bottles were attached to the left seat. Responding search and rescue personnel were interviewed. No oxygen bottles were observed at the site and neither occupant was wearing oxygen apparatus when they were recovered from the wreckage. The pilot's lap belt was found attached with the webbing cut by search and rescue personnel. The passenger's seat belt was attached, with the webbing separated from the structure.

Instrument approach plates were recovered in the wreckage. Most of the approach plates had expired between 20 and 2 months preceding the accident. Visual Flight Rules (VFR) sectionals were also located in the wreckage. One was current, and others not pertinent to the route of flight had expired by 2-4 months.

The airplane engine was disassembled and examined on October 14, 1999, at the aircraft recovery company where the airplane had been stored pending an examination. The engine remained attached to the forward airframe section by the engine mount. The propeller remained attached at the crankshaft flange. Portions of the oil sump, carburetor, and accessory case were impact damaged.

The top and bottom spark plugs were removed and examined. All four spark plugs were normal in color, when compared to the Champion Spark Plugs Check-A-Plug AV-27 chart, and had undamaged electrodes.

The vacuum pump was removed, and the crankshaft was rotated by hand through the drive pad. The crankshaft was rotated easily in both directions. Thumb compression was observed in proper order on all four cylinders. Normal lift action was observed at each rocker assembly. Mechanical continuity was established throughout the rotating group, valve train, and accessory section during hand rotation of the crankshaft.

Both the left and right magnetos were found securely clamped at the mounting pad. The magneto to engine timing was observed at 23 degrees BTDC of the cylinder number one on the left magneto, and 25 degrees BTDC of the cylinder number one on the right magneto. Both magneto's were removed from the engine and placed on a test fixture. Both magnetos were observed to produce spark at all four plug leads during the functional tests.

The carburetor was crushed and no fuel was found in the bowl. The throttle and mixture controls were found securely attached at their respective control arms at the carburetor. The fuel inlet screen was found free of any contamination. There was no evidence of foreign object ingestion or contaminates observed in the carburetor.

The two bladed constant speed propeller remained attached at the crankshaft flange and the blades remained attached to the propeller hub. The propeller blades displayed leading edge gouging and chordwise striations across the cambered surface, with large amounts of propeller blade material abrasively displaced and or missing near the tips and leading edges of the blades.


The Coroner's Office of Mono County, California, performed an autopsy on the pilot on September 27, 1999, with tissue and fluid samples retained for toxicological examination. The samples were submitted to the FAA Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma.

According to the toxicology report, the sample from the pilot was negative for all screened drug substances. The pilot was also tested for volatiles. All positive ethanols were confirmed by Radiative Energy Attenuation. No blood, urine, or vitreous was available for analysis. Small amounts of alcohol were detected in the muscle and kidney of the samples. According to the report, "the pilot was positive for Ethanol of 109 (mg/dL, mg/hg) detected in Kidney, 2 (mg/dL, mg/hg) Acetaldehyde detected in Kidney, 23 (mg/dL, mg/hg) Ethanol detected in Muscle, and 1 (mg/dL, mg/hg) Acetaldehyde detected in Muscle."


The wreckage was released to the insurance company representing the owner's estate on March 2, 2000.

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