TAFT, CA, USA
N986DB
Birx VANS RV-6
Without notifying air traffic control during a flight conducted under instrument flight rules, the pilot descended from 11,000 feet until impacting 900-foot msl terrain in a nose low attitude and with a relatively high rate of speed. At the time, visual meteorological conditions prevailed, and the sky was clear. Earlier, the pilot had departed California's central valley on a business flight with an intended southern California destination. En route communications were normal and the pilot was responsive to the radar controller's instructions to climb from 10,000 to 11,000 feet. About 1.5 minutes after receiving an updated altimeter setting, the airplane began descending. The pilot did not report vacating 11,000 feet, nor did he communicate the existence of any emergency. Minutes later, the airplane, which had just passed abeam the Tracy airport (closest airport to the airplane's location) reversed direction and turned toward Tracy. During the last 2 minutes of recorded flight, the airplane's descent rate averaged 1,550 feet per minute. Ground scar signatures were indicative of the airplane impacting terrain in a wings level attitude, and thereafter sustaining structural fragmentation. The impact occurred on level terrain about 1.3 miles short of the airport. The engine and propeller were found in a 3-foot-deep impact crater. Components were found as far as 317 feet from the crater. There was no evidence of fire. The pilot maintained his airplane on an annual inspection basis, and he had flown it since manufacture in 1998 for a total of 220 hours. He had made 64 flights in the airplane during the preceding 12 months. The pilot was reportedly in good health. The radar track plot provided evidence that the pilot successfully negotiated a course reversal turn and was initially able to head toward the nearest airport. The pilot was, however, unable to arrest the 1,550 foot-per-minute rate of descent. No evidence was found in the fragmented wreckage regarding the reason for the steep descent to ground impact.
HISTORY OF FLIGHT On March 27, 2000 about 1507 hours Pacific standard time, a Birx Vans RV-6, N986DB, owned and operated by the builder-pilot, descended into terrain about 2 miles southeast of the city of Taft, California. The homebuilt, experimental category, airplane was destroyed. The commercial certificated pilot and passenger were fatally injured. Visual meteorological conditions prevailed, and an instrument flight plan was filed. Family members and a business associate of the pilot reported that the pilot's intended destination for the business-related flight was Van Nuys, California. The flight was performed under 14 CFR Part 91, and it originated from Tracy, California, about 1347. Management at the Tracy Airport, where the airplane was hangared, verbally reported to the National Transportation Safety Board investigator that a check of fueling records revealed no fuel was pumped into the airplane during the 3 days that proceeded the accident flight. The management indicated that fuel prices tended to be higher at Tracy, and it was likely the pilot may have purchased fuel elsewhere. The management also reported that no one recalled observing the airplane depart on the accident flight. Federal Aviation Administration (FAA) personnel reported that the pilot was issued an instrument flight rules (IFR) clearance to Van Nuys. The pilot proceeded flying from the central California area in a southerly direction and climbed to 10,000 feet, as indicated by the airplane's Mode C equipped transponder. At 1402, the pilot was instructed to climb to 11,000 feet, in accordance with a revised instrument clearance. Between 1438 and 1458, air traffic control personnel communicated with the pilot on several occasions. The communications utilized different radio frequencies and addressed items including local altimeter settings, air traffic, transponder codes, and airplane altitude. The FAA indicated that all communications were routine. The last transmissions to and from the pilot occurred between 1458:17 and 1458:24. During this time interval, a Los Angeles Air Route Traffic Control Center (ARTCC) radar controller stated "experimental niner eight six delta bravo los angeles center burbank altimeter is two niner niner four." The pilot responded by stating "two nine nine four." Recorded radar data from the FAA's National Track Analysis Program (NTAP) indicated that, during this interval, the airplane was cruising about 11,100 feet while tracking in a southerly direction. Then, within 12 seconds after 1500:31, the airplane started descending. About this time, the airplane was passing abeam the Taft (uncontrolled) airport. At 1500:55, the airplane's transponder indicated it had descended to 10,800 feet. ARTCC personnel had not cleared the pilot to descend. A review of the FAA's voice communication recordings did not reveal evidence indicating the pilot had announced his departure from his last assigned clearance altitude of 11,000 feet. The airplane's descent continued, and about 1501:31 it descended through 10,000 feet. About this time the airplane's southerly ground track became northerly. During the last 2 minutes of recorded flight, the airplane's descent rate averaged about 1,550 feet per minute as it descended from 8,600 feet, at 1502:19, to 5,500 feet at 1504:19 (last recorded radar hit). During the last minute of recorded flight, the airplane continued toward the direction of the Taft airport. The airplane crashed about 0.2 miles from its last recorded radar position, and about 1.3 miles southeast of the Taft airport. (For additional details of the airplane's flight path and descent trajectory, see the Safety Board's "Recorded Aircraft Radar Study." Four witnesses were located who reported having seen or heard the descending airplane. None reported observing evidence of an in-flight fire. A written statement was provided by one of the witnesses. This witness indicated the airplane descended at a 45-degree angle and crashed at 1507. PERSONNEL INFORMATION The pilot was issued a private pilot certificate in 1971. In 1974 the pilot was issued commercial and certified flight instructor (CFI) certificates, and an instrument (airplane) rating. The CFI certificate expired in 1978. By the date of the accident, the pilot had logged a total of approximately 740 hours. The pilot's flight record logbook indicates that he first flew the accident airplane on June 21, 1998. During the 12-month period preceding the accident, the pilot flew his airplane on at least 64 occasions, which included trips under day, night, and actual instrument weather conditions. Flights were performed both within California from Tracy to Van Nuys, and across the country to Florida. AIRCRAFT INFORMATION FAA data indicates that the pilot completed manufacturing of his airplane in June 1998. The pilot maintained his homebuilt airplane on an annual inspection program. Since completion of the last annual inspection in June 1999, the pilot flew the airplane for 88 hours. The pilot's total time flying in his airplane, and the airplane's total time, are each about 220 hours. METEOROLOGICAL INFORMATION In pertinent part, at 1456, the Meadows Field, Bakersfield, California, reported its surface weather conditions as follows: Sky condition - clear; wind from 320 degrees at 10 knots; visibility 9 miles, and altimeter 29.91 inches of mercury. Bakersfield is located about 26 nautical miles and 030 degrees (magnetic) from the accident site. No reports of convective weather were reported in the area. WRECKAGE AND IMPACT INFORMATION The accident site was located on estimated 900-foot mean sea level open, level terrain. The site's approximate coordinates are as follows: 35 degrees 07.41 minutes north latitude by 119 degrees 25.54 minutes west longitude. The FAA coordinator reported that airplane ground scar signatures, in the vicinity of the estimated 200-foot-long wreckage distribution path, were consistent with the airplane having impacted the ground in an estimated 30- to 45-degree nose down and wings level attitude. The airframe structure fragmented upon ground impact, and debris was found spread out over a 50-foot-wide path on each side of the main debris field. Portions of all the flight controls were located along the wreckage path. The impact damaged engine and propeller assembly were located in a 3-foot-deep impact crater. Two stowed parachutes were noted in the debris field. There was no evidence of fire. Responding Taft Police and Kern County Coroner officials indicated that the principal axis of wreckage distribution was along a 160-degree course. Wreckage was located as far as 317 feet from the initial point of impact. MEDICAL AND PATHOLOGICAL INFORMATION The pilot held a second-class aviation medical certificate. The certificate was issued in May 1998, without limitations or restrictions. Family members reported that the pilot's health was excellent. No history of heart disease was noted in his family or with his parents. An autopsy was performed by the Coroner Division of the Kern County Sheriff's Department, Bakersfield. The medical examiner indicated that due to the traumatic nature of the injuries, no blood specimen was recoverable for follow up toxicology testing. The FAA's Civil Aeromedical Institute (CAMI), Toxicology and Accident Research Laboratory, performed toxicology tests from tissue specimens of the pilot. CAMI reported detecting doxylamine in muscle (0.055 ug/ml) and liver (0.267 ug/ml). Doxylamine is a sedating antihistamine present in over-the-counter medications. Due to its half-life period, without a blood level finding the drug's possible affects could not be established. No evidence of any other drugs was detected. No carbon monoxide level could be ascertained due to the lack of a blood specimen. TESTS AND RESEARCH The Safety Board investigator reviewed the en route communication recordings between the pilot and the FAA facilities between the period 1452 and 1507. No evidence of slurred speech, hesitation, or any lack of clarity was noted. The pilot responded within seconds to all air traffic control communications and/or instructions. The FAA's audio recordings of transmissions from the pilot were analyzed by the Safety Board's Vehicle Recorders Division. In summary, a sound spectrum study was completed and the transmissions were examined using an audio spectrum computer analyzer to identify any background sound signatures that could be associated with the accident airplane. The frequency response of the pilot's headset, the airplane's radios, and the air traffic facilities' recording systems were of such quality their combined attributes precluded the recording of background signatures from the airplane. ADDITIONAL INFORMATION The FAA coordinator responded to the accident site and performed the on-scene wreckage examination. No wreckage was recovered from the site or retained.
The in-flight collision with the ground for undetermined reasons.
Source: NTSB Aviation Accident Database
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