Aviation Accident Summaries

Aviation Accident Summary SEA98FA062

LODGEPOLE, MT, USA

Aircraft #1

N9131V

Mooney M20F

Analysis

After intentionally entering an area of adverse weather along his intended route, the pilot attempted to maneuver through forested mountainous terrain. While attempting to fly through the mountainous terrain in an area where visibility was limited by low ceilings, fog, snow showers, and drizzle, the pilot failed to maintain clearance from the trees.

Factual Information

HISTORY OF FLIGHT On April 6, 1998, approximately 0900 mountain daylight time, a Mooney M20F, N9131V, impacted trees while flying through mountainous terrain near Lodgepole, Montana. The private pilot, who was the sole occupant, received fatal injuries, and the aircraft, which was owned and operated by the pilot, was destroyed. The 14 CFR Part 91 flight, which was en route to a private airstrip on a ranch near Jordan, Montana, departed Havre, Montana, about 30 minutes prior to the accident, and was being operated in an area where ceilings were approximately 100 feet and visibility was reported to be less than one mile. No flight plan had been filed, and only two brief ELT transmissions were reported. According to local authorities, the pilot, who was campaigning for a seat on the State Public Service Commission, had arrived in Havre on the previous day in order to attend the Hill County Democratic Women's Annual Dinner. After spending the night in Havre, he was driven to the airport by a friend on the morning of the accident, arriving there a little after 0800. After arriving at the airport, he had Havre Flying Service add 25.9 gallons of 100 LL (low-lead) aviation fuel to the aircraft's right wing tank, and then departed for his ranch near Jordan a little after 0830. Witnesses who had interacted with the pilot at the airport prior to his departure said that he did not seem tired and showed no obvious signs of any physical problems. Witnesses also remarked that looking to the southeast it was apparent that there were low ceilings and "bad weather" along his attended route. One witness said that that he had asked the pilot if he thought the weather was going to be okay along the route, and the pilot replied "Yeah." But another witness who mentioned the weather to the pilot, said that the pilot told him that it looked bad enough that he was not sure how far he would be able to get. The next time the aircraft was sighted was around 0845, when it was observed about 23 miles northwest of Lodgepole near where Barney Olson Road passes the north end of Putnum Lake. The witness who saw the aircraft at that point reported that the pilot was flying under the low clouds and was "real low" to the ground. He said that he could clearly see the pilot in the window of the aircraft, and that they were close enough to each other that they both waved. There were no further reported sightings of the aircraft or contacts with the pilot, but there was one brief ELT transmission detected in the vicinity of Lodgepole that morning. The family reported the pilot missing on Monday evening, and the wreckage was ultimately found four days later on the edge of the Little Rocky Mountains about four miles southeast of Lodgepole. METEOROLOGICAL INFORMATION The automated METAR taken at Havre at 0900 on the morning of the accident reported winds from 080 degrees at eight knots, 10 miles visibility, an overcast ceiling at 1,800 feet, a temperature of 41 degrees Fahrenheit , a dew-point of 34 degrees, and an altimeter of 29.83 inches of mercury. Although the weather was VFR at the time the aircraft departed Havre, individuals who were at the airport at the time reported that they could clearly see that the weather in the pilot's intended direction of flight was much worse. Local authorities in Jordan reported that at the time the aircraft should have arrived there, the Jordan area was covered with clouds a few hundred feet above the ground, and that there were extensive areas of thick ground fog and light drizzle. Reports from the area around Lodgepole were of very low ceilings, light drizzle mixed with snow showers, and that the mountain tops were covered by clouds. During the investigation, it was determined that the pilot had not acquired a preflight weather briefing from any FAA facility. Contact was also made with the two providers of weather information through DUATS (Direct User Automated Terminal System), and both reported that on the day of the accident and the day prior, there had been no contact by the pilot or anyone seeking weather information for N9131V. WRECKAGE AND IMPACT INFORMATION The aircraft impacted coniferous trees about 4,600 feet above sea level (MSL) in mountainous terrain on the eastern edge of the Little Rocky Mountains. The aircraft came to rest at North 47 degrees, 58.89 minutes, West 108 degrees, 26.40 minutes. The initial impact was approximately 60 feet up a 100 foot tree, at a point where its diameter was about 10 to 12 inches. The aircraft then continued for approximately 280 feet on a magnetic heading of 155 degrees, impacting a series of trees that were growing on a 15 degree upslope. Both of the wings were torn from the aircraft as it passed though the trees, with the fuselage, empennage, and engine compartment continuing to the end of the impact tract. The entire fuselage, except for the empennage, had been destroyed by an intense fire, and the empennage itself was significantly distorted where it was wrapped around part of a tree at the point where the fuselage came to rest. The wing sections that came off as the aircraft moved down-track were inspected, and numerous deep indentations were found in the leading edges. On all of these indentations, the lateral and longitudinal axis of the indentation was aligned within 10 degrees of the lateral and longitudinal axis of the aircraft. Although the left main gear had been torn from the wing, the right main gear and the nose gear where both retracted. Because of the extent of the damage to the wings and the intense fire in the fuselage, flight control continuity could not be determined, but the flap actuating linkage was consistent with the flaps being in the retracted position. The engine was still attached to the firewall, and the crankshaft flange, along with one blade of the propeller, was still attached to the crankshaft. The detached blade was not found, but the one that remained showed longitudinal twisting, and the outboard three inches of its span was curled back almost 90 degrees. The blade showed no leading edge indentations, and there was no evidence of chord-wise scarring. One spark plug was removed from each of the four cylinders, and all showed minimal electrode wear and no evidence of contamination or significant lead deposits. The oil screen was removed, and there was no indication of contamination or significant metal chip build-up. Fuel was found in the spider manifold and in the lines to the individual injector nozzles. Through partial rotation of the crankshaft, mechanical continuity was established from the crankshaft, through the accessory gear, to the camshaft, pushrods, rockers, and valves. In addition, the dry vacuum pump was disassembled, and the rotor and vanes showed no signs of excessive wear or damage, and there was no evidence of vacuum system contamination. ADDITION DATA AND INFORMATION At the completion of the investigation, the aircraft was released on September 3, 1998, to Rod Weeding, the pilot's son. At that time the wreckage was still located at the site of the accident. An autopsy was performed on the pilot in Great Falls, Montana, by Dr. B .D. Patterson, M.D., and the cause of death was determined to be blunt force trauma to the chest, with associated hemorrhage into pleural cavities and pericardium. A toxicology examination was performed on the pilot by FAA's Toxicology and Accident Research Laboratory, and no ethanol was detected in the vitreous fluid. Tests for carbon monoxide and cyanide could not be performed due to a lack of suitable specimen. A test for drugs revealed 0.71 (ug/mL) of Paroxetine (an antidepressant) in the kidney tissue, and 1.608 (ug/mL) of Paroxetine in the liver tissue. It was also determined that the pilot's last FAA flight physical had been performed on May 13, 1992.

Probable Cause and Findings

The pilot's failure to maintain clearance from the terrain after flying into an area of known adverse weather. Factors include low ceilings, fog, snow showers, drizzle, and trees along his intended route.

 

Source: NTSB Aviation Accident Database

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