LAX96FA096

The pilot was operating on a VFR on top IFR clearance when he inadvertently encountered a mountain wave condition while flying in a dark moonless night. The radar data showed that the airplane began a 612 FPM descent for 1,000 feet and then abruptly climbed 300 feet before the airplane's transponder code disappeared from the sector controllers radar screen. The pilot did not make any radio transmissions during the accident sequence of events. The airplane crashed in a vertical nose-down attitude into a lake and was buried about 20 feet in the muddy silt terrain. The wreckage examination disclosed no evidence of an in-flight breakup or any preexisting airplane malfunctions or failures.

History of Flight

On January 19, 1996, about 2147 hours Pacific standard time, a Beech E-55, N4088A, crashed into a lake about 2 miles east of Cedarville Airport, Cedarville, California. The pilot was conducting an instrument flight rules (IFR) personal flight to North Las Vegas Airport, Las Vegas, Nevada, and was operating on a visual flight rules (VFR) on top clearance. The airplane, recently purchased by the pilot's company, Sturdy Welding Equipment & Design Company, Lynnwood, Washington, was destroyed by impact forces; there was no fire. The certificated private pilot and his passenger sustained fatal injuries. Instrument meteorological conditions prevailed. The flight originated at Paine Field, Everett, Washington, at 1943.

A Seattle [Washington] Flight Service Station quality assurance specialist said that the pilot contacted the facility on the radio at 1938 when the airplane was on the ground at Paine Field. The pilot changed the number of persons on his flight plan from four to two. The pilot did not obtain, nor did he request, a weather briefing.

The FAA Seattle Terminal Radar Approach Control (TRACON) manager said the pilot received routine services from the facility.

The FAA, Seattle Air Route Traffic Control Center (SEA ARTCC) communications transcript show that the pilot initially contacted the facility about 1946:11. The pilot requested and received a VFR on-top clearance. At 2042:05, the pilot reported to the SEA ARTCC sector 30 controller that he was flying at 14,500 feet (all altitudes, unless otherwise noted, are mean sea level altitudes). The sector controller acknowledged this transmission. Between 2042 and 2147, the pilot made three routine transmissions.

At 2147:37, the sector 30 controller transmitted, "baron four zero eight eight alpha radar contact lost report eight zero southeast [of] lakeview vortac." The pilot did not respond to this transmission. The sector controller then requested Delta Flight 1465 and subsequently Alaska Flight 594 to attempt radio contact with N4088A; he also asked the flights to monitor the emergency frequency for an emergency locator transmitter (ELT) signal. Both airplanes, at separate intervals, transmitted to N4088A, but did not receive a response, nor did they receive an ELT signal.

At 2152:06, the sector 30 controller contacted the Oakland [California] ARTCC and advised the sector 44 controller that he had lost radar and radio communications with N4088A when the flight was descending through 12,300 feet. The sector 44 controller said that N4088A's altitude was below his radar coverage area, and that he would not be able to see the radar target.

The sector 30 controller also asked the Oakland ARTCC sector 45 controller to attempt to contact N4088A. The sector 45 controller said that he had already tried to contact the airplane, but without success.

The available radar data showed that N4088A began a climb to 13,500 feet at 2144:46. At 2145:11, N4088A began a descent to 12,000 feet, arriving at that altitude at 2146:00, and then began a climb to 12,300 feet. N4088A reached 12,300 feet at 0546:12; this was the last radar target on the airplane. The airplane's linear descent rate between 13,500 and 12,000 feet was about 612.25 feet/minute; the linear climb rate between 12,000 and 12,300 feet was 1,500 feet/minute. There were no witnesses.

The crash site coordinates are: 41 degrees, 33.14 minutes north latitude and 120 degrees, 06.20 minutes west longitude.

Pilot Information

The pilot held a private pilot certificate with airplane single engine land, airplane multiengine land and instrument airplane ratings. He also held an unrestricted third-class medical certificate dated January 4, 1994.

Safety Board investigators recovered two pilot flight hours' logbooks. One logbook was fragmented into little pieces and no information could be obtained from it; the other logbook did not have the pilot's name on it, but it contained several entries. The entries began on December 1995, and ended on January 1, 1996. The total flight hours of the entries were 18.2 hours.

According to the FAA Medical Records, the pilot showed in his last medical application form that he accrued 704 flight hours. According to the FAA Airman Records Section, the pilot received his multiengine rating from an FAA approved school on May 1, 1995. The pilot flew a Piper PA-23-160 for the rating. The successful completion of the multiengine rating satisfied the biennial flight review requirements of current federal air regulations.

Aircraft Information

Safety Board investigators recovered the aircraft maintenance logbooks. Examinations of the logbooks revealed that the aft fuselage structure and aft cabin top skins, both horizontal stabilizers' skins, both wings' skins, and the vertical stabilizer skins were replaced on March 1, 1995.

The last annual inspection was accomplished on March 2, 1995. At the time of the inspection, the airplane accrued 3,245.7 hours. The airplane's recording hobbsmeter was not found. According to the pilot's secretary, the pilot flew the airplane about 250 hours since the last annual inspection. She estimated this flight time based on the pilot's previous fuel purchases.

Both engines were remanufactured by Teledyne Continental Motors on April 10, 1984. On February 25, 1994, both engines were overhauled by an engine repair station. At the time of the last annual inspection, the engine accrued about 150 flight hours since they were overhauled.

Meteorological Information

The National Transportation Safety Board, Office of Aviation Safety, Operational Factors Division meteorologist completed a weather study for the accident area at the time of the accident. The weather study showed:

1. Visual meteorological conditions prevailed along the route of flight. 2. The upper winds were between 290 and 300 degrees at 40 to 45 knots between 12,000 and 1300 feet msl. 3. The temperature between 12,000 and 13,000 feet was minus 14 to 16 degrees Celsius. 4. Mountain wave activity was present near the accident site. The wavelength of the wave clouds averaged about 9 nautical miles. An enhanced north-northeast, south-southwest oriented lee wave cloud was located east of the Warner Mountain Range. The Warner Mountain Range is west-northwest of the accident area. The western edge of the wave cloud was between 4 and 5 nautical miles east of the Warner Mountain Range ridge line. The width of the cloud was about 5 nautical miles. 5. The temperature dropped sharply when N4088A was at 41 degrees, 13 minutes north latitude and 120 degrees, 10.56 minutes west longitude (radar position at 2144:34 hours). According to the meteorologist, this temperature drop shows that the western edge of the lee wave cloud was at this position. 6. Light to moderate icing conditions existed in the wave cloud. 7. The National Weather Service Area Forecast and Winds Aloft Forecasts for the accident area were substantially correct.

According to the computer generated astrological data, at the time of the accident the altitude of the moon was 52.1 degrees below the horizon and had zero percent illumination.

Wreckage and Impact Information

The aircraft retriever said that the crash site was in a lake about 2 miles east of the Cedarville Airport. Most of the airplane was buried in the muddy and silty terrain. Both engines were found about 20 feet beneath the surface facing in a north-northeasterly direction; the remainder of the airplane was found above the engines. The retriever said that both engines were impacted in the mud in a near vertical descent attitude. Scattered airplane debris was found 90 yards in front of the 20-foot impact crater in a north to east quadrant.

Safety Board investigators examined the airplane on March 6, 1996, at Specialty Aircraft Company, Redmond, Oregon. Except for the FAA inspector listed in th