NTSB Factual Report

HISTORY OF FLIGHT

On April 26, 1998, approximately 1630 mountain standard time, a Cessna T310R, N467DL, registered to and operated by the pilot, was destroyed when it collided with terrain near Pie Town, New Mexico. The instrument rated commercial pilot was fatally injured. Although visual meteorological conditions were reported along the route of flight, instrument meteorological conditions were said to prevail in the accident area. No flight plan had been filed for the personal flight being conducted under Title 14 CFR Part 91.

The airplane departed Carson City, Nevada, in the company of another airplane at 1105 Pacific standard time. According to the Federal Aviation Administration (FAA), the airplanes parted company north of Las Vegas, Nevada. N467DL was initially tracked by the Los Angeles Air Route Traffic Control Center (ARTCC). When it entered Nellis Air Force Base airspace, the pilot was issued a discrete transponder code, and he reverted back to code 1200 when he exited. The airplane was subsequently tracked by the Albuquerque ARTCC. The pilot advised another pilot that he would be "GPS (Global Positioning System) direct to Las Cruces. True airspeed, 180 (knots)." At 1609, the target disappeared from radar at a point 13 miles west of Springerville, Arizona. The pilot's wife reported the airplane overdue, and an ALNOT (Alert Notice) was issued that evening at 1805.

An extensive aerial and ground search was to no avail. The initial missing airplane report was filed by NTSB's Southwest Regional Office (see LAX 98-A-MS01). On September 13, 1998, elk hunters and outfitters spotted the wreckage in the Sawtooth Mountains on property belonging to the JMG Ranch, about 2.5 miles east of Pie Town, New Mexico.

CREW INFORMATION

The pilot, Bertines Jacob Zwaagstra, age 53, was born on October 9, 1944. He held Commercial Pilot Certificate No. 551624017, dated August 9, 1997, with airplane single/multiengine land, instrument-airplane, and rotorcraft-helicopter ratings. He also held a third class airman medical certificate, dated October 9, 1997, with a restriction for wearing corrective lenses.

The pilot became a USMC helicopter pilot in 1969. No logbook was located but when the pilot made application for his airman medical certificate, he reported he had logged a total of 2,500 hours. He was a dairyman and owned the BJZ Dairy in Mesquite, New Mexico.

AIRCRAFT INFORMATION

N467DL, a Cessna T310R (s.n. 310R0619), was manufactured by the Cessna Aircraft Company in 1976. It was equipped with two Teledyne Continental TSIO-520-B engines (s.n. 500290, left; 500328, right), each rated at 285 horsepower; two McCauley 3-blade, all metal, constant speed, full feathering propellers, and two AiResearch (Garrett) turbochargers. The pilot purchased the airplane on July 14, 1997.

Data found in Supplement B of this report is based on equipment documents, dated November 10, 1975, when the airplane left the factory.

METEOROLOGICAL INFORMATION

In the area of the accident, weather radar coverage was poor and surface weather observation stations were nonexistent. However, satellite photos indicated extensive cloud cover in the area. Documents submitted by WeatherData, Inc., forecasted convective activity for the area.

Arrows were superimposed on the satellite photographs to depict the approximate location of the accident site. These photographs show breaks in the clouds. Radar plots of the N467DL approximate these breaks in the clouds.

Gallup, New Mexico, located approximately 95 miles northwest of the accident site, reported thunderstorms throughout the day of April 26. Show Low, Arizona, located 97 miles west of the accident site, reported a 2,000 foot broken ceiling at 1550, and a 1,000 foot overcast ceiling at 1745.

WRECKAGE AND IMPACT INFORMATION

The on-scene investigation commenced and terminated on September 14, 1998.

The airplane struck the rock face of a mountain at the 8,700 foot level at a location of 34 degrees, 19.38 minutes north latitude, and 108 degrees, 03.36 minutes west longitude, or about 2.5 miles east of Pie Town, New Mexico. The accident site was about 50 miles north of the direct route between Carson City, Nevada, and Las Cruces, New Mexico. Impact heading was measured as 030 degrees magnetic. Five distinct impact marks were noted on the rock face, consistent with and being of the same measurements as the left tip tank, left engine, nose section, right engine, and right tip tank. These markings were generally in a level attitude. The wreckage slid 50 feet vertically and came to rest directly beneath the impact marks on a 15 foot wide ledge. Postimpact fire consumed the cabin area.

All major structural components were identified and recovered. The degree of aircraft damage precluded establishing control continuity. The landing gear and flaps were retracted. The aileron trim tab actuator rod was identified and was extended 1.75 inches.

Both engines separated from the airplane but were recovered. Three of the six propeller blades were recovered. They were twisted, bent, and gouged, and the cambered surfaces bore chordwise scratches. Neither propeller hub was recovered. Portions of both turbochargers bore rotational scoring and impact marks on their compressor and turbine shrouds.

MEDICAL AND PATHOLOGICAL INFORMATION

An autopsy (report #4213-98) was performed by the New Mexico State Medical Examiner's Office in Albuquerque, New Mexico. Toxicological tests were not possible.

TESTS AND RESEARCH

Radar data on N467DL was obtained from the Albuquerque ARTCC. According to this data, between 1550:05 and 1604:26 the airplane flew at 13,500 feet at an average ground speed of 185 knots. At 1605:34, the airplane was at 13,400 feet and descending. The descent continued until 1609:53 when the target went off the radar screen at an encoded altitude of 10,500 feet. During this time, the ground speed was 209 knots and the rate of descent was 669 feet per minute. The accident site was 75 miles east of the last known radar position.

ADDITIONAL INFORMATION

In addition to the Federal Aviation Administration, parties to the investigation included the Cessna Aircraft Company and Teledyne Continental Motors.

The wreckage was released to a representative of the pilot's insurance company on September 14, 1998.

NTSB Probable Cause

The pilot's continuing VFR flight into instrument meteorological conditions. Contributing factors were weather conditions, that included clouds, and mountainous terrain.