United States of America

The airplane was observed to approach the airport from the northwest. As it crossed the northeast end of the runway, it initiated a right turn to cross the runway about the midpoint to a position for a left downwind for landing on runway 5. Its altitude was estimated to be about 200-300 feet above the ground and the landing gear was down. The witness did not observe the airplane further. It collided with the ground about 0.4 miles from the threshold. The morning sun was about 10° above the horizon and was about 33° to the right of the runway centerline. It would have been in the pilot's face during his flight from the last departure point. The landing runway sloped upward from the landing threshold. The lower-than-normal traffic pattern, the sun's position in relation to the airplane flight path, and the runway slope could have caused the pilot to perceive his altitude as being higher than it actually was. All three occupants were killed.

The pilot-owner decided to overfly a glacier which was located in the Sierra Nevada Mountains. The glacier was located near the 12,000 foot msl base of a 14,000 foot msl mountain near the head of a box canyon. Witnesses reported clearly observing the aircraft enter the canyon area. When the aircraft was nearly over the glacier the aircraft was observed to commence a course reversal. During the turn the aircraft stalled, descended rapidly and crashed into rocky 40° upsloping terrain whereupon it burned. The pilot, sole on board, was killed.

After landing at the aircraft's manufacturer facility with an asymmetric fuel condition and an inoperative yaw damper the crew elected to continue the flight to their destination without correcting the deficiencies. Enroute the captain informed air traffic controllers that he had fuel coming from one tank and that he doubted that had fuel available to reach his destination. The controller cleared the aircraft to land at a March AFB, the nearby airport. As the aircraft turned onto the final approach it rolled inverted and impacted the ground inverted short of runway 32. Both pilots were killed.

The crew was positioning the aircraft in preparation for a revenue flight and executing a non-directional beacon (NDB) approach to runway 05. The captain reported that the copilot was flying the aircraft. However, the captain stated that he took control of the aircraft during the approach and made some control corrections before returning control of the aircraft to the copilot. Radar data indicated that aircraft control was erratic throughout the approach and that the airspeed and descent rates were high (3,000 fpm sink rate) shortly before the accident. The aircraft struck a fence short of the runway and impacted the ground. The captain said he realized the aircraft was drifting left of course but did not correct it. He said he told the copilot to add power twice during the approach. The copilot's training history indicated difficulty in control, scan of instruments, and with instrument procedures. Company management described the captain as passive and the copilot as aggressive. Supervision of training and operations by management and surveillance of the company by the FAA was considered inadequate by NTSB.

Flight entered near vertical descent while flying in area of level 1 and 2 thunderstorms just after pilot had called requesting permission to deviate around rain showers. A level 5 thunderstorm was present 8 miles west. The aircraft descended at rates up to 13,800 feet per minute. Witnesses saw aircraft exit bottom of clouds at approximately 4,000 feet in a near flat attitude and rotating around the yaw axis to the left. Engine sounds increased and decreased as the aircraft rotated and all components appeared to be present on the aircraft. No smoke or flame was visible. At approximately 500 feet above the water the rotation stopped and the nose dropped to a 30 to 70° nose down angle and both engines could be heard increasing in power. Before the recovery could be completed the acft struck the ocean. The pilot, sole on board, was killed.

After abt 4.3 hours on an overwater flight, the crew reported they had 15 minutes of fuel remaining. Subsequently, 3 of 4 engines lost power from fuel exhaustion. During an emergency landing, the aircraft hit a levee and was extensively damaged. Most of the wreckage came to rest in a drainage canal. Bodies of the crew were recovered from the water on 7/22/88. During an investigation, no fuel was found in the fuel tanks and no fuel spill was evident. Records showed the aircraft had departed El Salvador with 7 hours of fuel. No reason for the loss of 2.7 hours of fuel was verified; but about 1 month after the accident, an employee of the operator reported finding an open drain valve in the wreckage, inside the #4 engine nacelle. A metallurgical examination indicated the valve had been in an open position for an extended time. No ground personnel saw fuel draining from the aircraft during start, taxi or takeoff. The crew had no control of the valve in flight. There was evidence the #1, #2 and #3 engines were not providing power during impact. All crossfeed valve controls were found in crossfeed positions. Ethanol was found in the pilot's and copilot's blood, but there was evidence that it was the resulted of postmortem changes.

This was the first flight after a maintenance inspection. The flaps were left full down after a post-inspection by company mechanics, before the flight. Witnesses stated the flaps were down when the aircraft taxied to takeoff on runway 19L. Witnesses stated the aircraft climbed steeply after it lifted off with a pitch attitude up to 60°. According to witnesses, the aircraft climbed to 200 to 500 feet agl, before it stalled and descended nose down in a left turn. The aircraft crashed about 300 ft left of and 2000 ft down the rwy. Examination of the aircraft revealed the flaps were full down. The scroll type checklist was positioned at the beginning of the takeoff check. The flight manual recommends a 10 degree flap setting for takeoff and prohibits flap full down takeoff. Review of previous DHC-6 accidents involving flap full down resulted in a steep takeoff climb and excessive pitch attitude followed by a stall. The position of the control lock suggests it may have been in the locked position during the takeoff. The pilot, sole on board, was killed.

Before reaching his descent, the pilot advised approach control that his right engine was 'blowing some smoke' and losing oil pressure. Vectors were provided for a visual approach, but there were low clouds in the area and visibility was restricted due to haze. After reaching the vicinity of the airport, the pilot said it was in sight and he was entering a downwind for runway 30. Witnesses saw the aircraft on a left downwind, but said the aircraft overshot the 1st turn to final approach. Subsequently, while maneuvering to land, the aircraft crashed approximately 2,500 feet northeast of the runway in a wooded area. Witnesses agreed the aircraft was slow and in a steep right turn with the gear extended before it crashed in a steep descent and burned. An examination revealed evidence the starter on the right engine had backed off; 3 starter bolts had fractured thru the threaded area with signs of fatigue cracking; wear marks on the starter gear and engine gear ring indicated the starter motor had shifted aprx 3/4' rearward. Also, there was evidence the torsional damper was loose on its shaft before the accident and that both props were operating at low pitch during initial impact.

The DHC-6 Twin Otter, C-GKBM, was under contract to the U.S. Forest Service. It was to be repositioned to John Day, OR to pick up passengers. At 11:35 PDT, the pilot checked in with John Day Dispatch and transmitted his expected time of arrival would be 12:15 PDT. About 11:40 the aircraft contacted three trees with the right wing at the 5,000-foot level of Battle Creek Mountain. This impact separated the wing into three sections before the aircraft "exited" over the mountain edge. The final impact site was on this ridgeline with the aircraft coming to final rest in a steep canyon to the east. There was a high mountain further east on the flight path that also needed to be crossed before a descent to John Day, Oregon could be commenced. The pilot's medical records indicated the he had been having medical problems, some of which he did not want brought to the attention of the Medical Doctor (MD) designated by the FAA to do flight physicals. In addition, he did not tell his supervisor that he was having medical problems. It was noted that he had complaints of chronic muscular neck pains, back problems, falling asleep, allergy problems, numbness in the top of his feet, feeling tired and run down, and pain in his legs. The flight track showed a gradual descent of about 400 feet per minute. He was off course to the right for about five minutes before impacting with trees. This flight tract strongly supported a very high probability of sleep-induced unconsciousness.

The relatively low time, non-instrument rated, private pilot flew passengers to Savannah, GA. On the return flight, he made a refueling stop at Knoxville, TN. He filed no flight plan at Knoxville and no record of an en route weather briefing was found. At 2236 edt, the pilot contacted the tower and said he would 'like to VFR to Louisville with a heading of 330°. He took off at 2249 and received departure vectors until cleared on course. Radar service was terminated, 23 miles northwest of Knoxville. Subsequently, the aircraft hit trees and crashed on rising terrain near the top of a ridge, 30 miles northwest of Knoxville. Impact occurred at approximately 3,000 feet msl on a heading of 290°. Weather at Knoxville (elev 930 feet) was in part: 3,700 feet overcast, visibility 5 miles with fog and rain. No evidence of a preimpact part failure or malfunction was found during the investigation. Mountain peaks in the vicinity of the crash site were up to 3,390 feet. The pilot, sole on board, was killed.