LAX00FA178

There were no witnesses to the accident. A passing motorist saw the tail of the aircraft sticking out of a lake and notified authorities. Crush lines on the recovered wreckage disclosed that it impacted the water right wing low with a pitch attitude in excess of 45 degrees nose down. No preimpact mechanical malfunctions or failures were identified. The pilot rented the airplane and flew 47 miles to the mountain resort airport, landed, met some of his future in-laws, and loaded three of them onboard for a local sightseeing trip around the lake. He obtained his fixed wing private certificate 2 weeks prior to the accident, and this was the first flight with passengers. During training, he had only 1 flight involving a high-density altitude airport, with the balance of his training conducted at airports with elevations less than 1,000 feet msl. The density altitude at the accident site was 5,400 feet. The lake is in an oval shaped mountain valley 25 miles long by 15 miles wide surrounded by mountains, which rise 3,000 to 4,000 above the water's surface. The town and the airport are at the northwest end of the lake. The town borders the airport to the north, and mature pine trees that are 50 to 60 feet in height surround the field and provide obstacles for an approach or departure on any runway but 16/34. The airport manager said that because of the terrain and obstacles, and the proximity of the noise sensitive town to the north, pilots typically land on runway 34 and takeoff on runway 16. While he could not be certain, the airport manager believes the airplane departed on runway 16. The location of the wreckage would be consistent with an upwind to crosswind turn point for runway 16. The aircraft was found in a takeoff and initial climb configuration. Based on the aircraft's recording hour meter and the stopped electric clock, the accident occurred in the initial climb from takeoff on runway 16. The performance data for the airplane establishes it would have climbed to between 400 and 500 feet agl as it reached the accident location. Using flight planning charts for the airplane, the elapsed time on the recording hour meter does not support a conclusion that the pilot completed a run-up or had any appreciable ground run time prior to the accident takeoff. Between 1500 and 1600, the airport's automatic weather observation station recorded winds from 289 degrees at 9 mph with peak gusts to 23 mph. The system only records the highest peak wind gust during the hour-long observation period; however, it does not record the time of the wind peak. Surface winds are affected by friction and Coriolis deflection, which will produce an average increase in wind speed of 10 mph at the boundary between the layer next to the surface and the free flow layer above, which is typically about 400 feet agl. Coriolis deflection will cause the wind direction to change clockwise at the boundary, with a typical direction change of 10 to 20 degrees. Katabatic wind effects in mountainous areas can result in a rapidly moving air mass, which if an inversion layer is present, may flow over the lower layer. Therefore, the takeoff roll on runway 16 would have been with a right quartering tailwind, which moved closer to a direct tailwind and increased in speed as the aircraft climbed through 400 feet. Considering the recorded peak wind speed, it is likely the aircraft encountered a rapid change in wind velocity by as much as 25 to 30 mph. The flaps-up stall speed at zero degrees of bank is 44 knots indicated airspeed (KIAS) and 47 KIAS with 30 degrees of bank angle. Normal initial climb segment airspeed is 74 KIAS at 5,000 feet msl.

History of flight

On April 28, 2000, between 1500 and 1620 hours Pacific daylight time, a Cessna 172P, N216PB, collided with the surface of Lake Alamanor near Chester, California. The airplane was operated by Pacific Flight Services of Chico, California, and was rented by the pilot for a personal flight. The aircraft was destroyed in the collision sequence and sank. The private pilot and his three passengers sustained fatal injuries. The airplane was being operated under 14 CFR Part 91 as a personal flight when the accident occurred. The flight is believed to have departed the Chester airport between 1500 and 1530 for a local sightseeing flight around the lake. Visual meteorological conditions prevailed and a flight plan was not filed for the flight.

No witnesses to the accident were identified by either Safety Board investigators or investigating officers from the Pulmas County Sheriff/Coroner's Office.

Investigation disclosed that the pilot rented the airplane from the operator and departed from the Chico airport about 1430 and flew to the Chester airport, a distance of 47 miles. At the Chester airport, the pilot met with his fiance, her grandparents, and her younger brother. According to the fiance and other family members, the pilot loaded his fiancee's grandparents and her younger brother onboard the airplane to go sightseeing around the lake while the fiance waited for the group to return. This was the pilot's first flight with passengers since obtaining his fixed wing private pilot certificate 14 days prior to the accident.

The airport manager and owner of the local fixed base operation (FBO) on the field witnessed the group of people walk out to the accident airplane and get in. He said he was about 100 feet away from the airplane and he heard it start up and also heard the subsequent takeoff. He said that he owns a Cessna, and the engine sounded "typical" and normal. The airport manager said he is also an airframe and power plant mechanic with inspection authorization. While he did not note the exact time, he believes that the airplane took off somewhere between 1500 and 1530.

The airport manager said that pilots typically land on runway 34 and depart using runway 16 so that they fly over the lake and not the noise sensitive town of Chester. He said he could not be 100 percent certain, but he believed the pilot departed on runway 16 out over the lake.

Shortly after 1600, a motorist driving along the west shore of the lake observed the tail of an airplane sticking out of the water and went to the U.S. Forest Service ranger station across the street from the airport to report the sighting. According to Pulmas County Sheriff's office, the 911 emergency call from the U.S. Forest Service office reporting the aircraft wreckage sighting was logged at 1625.

The location of the wreckage was plotted on a USGS survey map by the responding search and rescue personnel from the Pulmas County Sheriff's office. The location as plotted was later determined to be about 4,600 feet on a magnetic bearing of 132 degrees from the approach end of runway 34 (or the departure end of runway 16). The location is 0.4 miles east of the lake's north-south oriented western shoreline. According to the airport manager, the position of the wreckage would be consistent with either a upwind to crosswind turn point for runway 16, or, a base to final turn point for runway 34.

Personnel information

The pilot's personal flight records, the operator's records, and the Federal Aviation Administration (FAA) airman and medical records files were reviewed. He held a private pilot certificate with ratings for rotorcraft helicopters and single engine land airplanes. The rotorcraft helicopter rating was issued on August 1, 1999, and the airplane single engine land add-on rating was issued on April 14, 2000. The pilot's most recent third-class medical certificate was issued without limitations on September 1, 1998.

According to the pilot's flight logbook he had 131 hours total time, with 68 hours in rotorcraft, and 63 hours in fixed wing airplanes. All of the fixed wing flight time was amassed in Cessna 172 aircraft between September 1999 and the accident. Over half of the flights, including the pilot's practical flight test, were listed in the accident airplane. Of the 63 fixed wing flight hours, 10 were recorded as pilot-in-command. No logbook entries were recorded between the pilot's fixed wing practical flight test on April 14 and the date of the accident. Based on the identifiers listed in the logbook for flight origin and destination points, the highest elevation airport used by the pilot was about 2,500 feet msl, and only one flight was recorded to that airport. The balance of the flight activity was conducted in the greater San Joaquin Valley of California at airport elevations below 1,000 feet msl.

According to family members, the passenger in the right front seat did not have any prior aeronautical experience. No record of the individual was found during a review of the FAA airman and medical records database.

Aircraft information

The Cessna 172P, serial number 17274440, was manufactured in November 1980, and had accrued a total time in service of 9,005 hours. The most recent annual inspection was completed on February 4, 2000, 156 hours prior to the accident. In addition, a 100-hour inspection was accomplished on April 5, 2000, 58 hours prior to the mishap. A Lycoming O-320-D2J engine, serial number L-1046-39A, was the original Cessna factory installed engine in the airframe and had accumulated the same total time in service as the airframe. The engine had accrued 1,052 hours since the most recent major overhaul. Annual and 100-hour inspections were accomplished on the dates noted for the airframe. In addition, a 50-hour inspection was completed the day prior to the accident. Review of the operator's aircraft status sheet and maintenance department records disclosed that there were no unresolved discrepancies at the time the pilot rented the airplane.

The operator's records revealed that the airplane was refueled on the morning of the accident with the addition of 15.1 gallons of 100LL aviation gasoline. The operator reported that the addition of the fuel topped the aircraft standard range tanks to capacity (43 gallons total, 21.5 in each tank). Another renter pilot flew the airplane for 1.2 hours before the accident pilot rented it; comparison of the recording hour meter reading at the accident site and on the operator's rental log sheet for the pilot's departure from Chico revealed that the accident pilot flew the airplane for a total of 0.6-hours. Using average fuel consumption rates in the airplane flight manual climb and cruise performance charts, investigators conservatively estimated that the airplane had about 20 gallons of fuel onboard at the time of departure from the Chester airport. The disposition of the fuel load between the two standard capacity wing tanks could not be determined.

As noted above, the recording hour meter registered 0.6 hours from the time the pilot took the airplane at Chico. Using the performance charts in the Cessna Aircraft Information Manual for the airplane, the flight time from Chico to the Chester airport was computed (the charts are appended to this report). The performance charts include adjustment factors for the takeoff and climb variances from cruise. A climb to 6,000 feet was assumed in the computations, along with a cruise at 75 percent power, and an additional 6 minutes was factored in for the start and taxi at Chico, and the taxi in to parking at the Chester Airport. The total elapsed time thus derived was between 32 and 38 minutes, or, 0.6 hours on the recording hour meter.

Weight and balance computations were made for the takeoff at Chester, and at a zero fuel condition. The airplane empty weight, total moment, and center of gravity