United States of America

The crew was conducting a GPS instrument approach in a Douglas DC-6B airplane under IFR conditions. Both pilots were certificated and type-rated in the Douglas DC-6B airplane. The first pilot, seated in the right seat, was one of the company's senior check airman, and possessed a right seat dependency endorsement. The second pilot, seated in the left seat, had less experience in the DC-6B airplane. It had been previously agreed that the second pilot would fly the leg of the flight on which the accident occurred. The first pilot reported that light snow showers were present, with visibility reported at 4 miles. During final approach as the airplane passed over the airstrip threshold, a higher than normal sink rate was encountered. He said that the initial touchdown was "firm," but was thought to be within acceptable tolerances. Just after touchdown, the left wing broke free from the airplane at the wing to fuselage attach point. The airplane veered to the left, continued off the left side of the 5,000 feet long by 75 feet runway, down an embankment, and came to rest in an area of wet, tundra covered terrain. A postcrash fire heavily damaging the center section of the fuselage. The cockpit voice recorder (CVR) revealed that as the airplane progressed along the approach, the first pilot says: "You're only one mile from it....Take it on down ah three." As the airplane passes over the runway threshold, the first pilot says: "Keep that, keep that (expletive) power off.... Just push forward on the nose." The sound of impact is heard 4 seconds later. The minimum descent altitude (MDA) for the approach is 400 feet msl (383 feet agl). A contract weather observer reported lower ceilings, with about 1 mile visibility, over the approach end of the runway at the same time as the accident.

The airplane was on a non-scheduled cargo flight which was projected to fly an approximate 240 degree course for 92 nm. The accident site was located on a heavily forested steep mountain side, 15 to 16 nm north of the airplane's projected course. The debris field began at an east-west ridge line, and progressed for 300 feet on a 010 degree track to the downed airplane. Examination of the airframe and engines revealed no evidence of preimpact discrepancies. The accident site was in an area where the Fall color of the aspens was at its peak. Additionally, it was an area where elk were sometimes observed.

The Boeing 757 departed Newark Airport at 0847LT on a regular schedule service to San Francisco, carrying 37 passengers and a crew of seven. Few minutes later, the aircraft was hijacked by terrorists who modified the flight path and apparently attempted to fly over Washington DC. At 1030LT, the aircraft crashed in an open field located about 4 km north of Shanksville. The aircraft disintegrated on impact and all 45 occupants were killed. The terrorist attacks of September 11, 2001 are under the jurisdiction of the Federal Bureau of Investigation. The Safety Board provided requested technical assistance to the FBI, and this material generated by the NTSB is under the control of the FBI. The Safety Board does not plan to issue a report or open a public docket.

The Boeing 757 departed Washington-Dulles Airport at 0810LT on a regular schedule service to Los Angeles, carrying 58 passengers and a crew of six. Few minutes later, the aircraft was hijacked by terrorists who modified the flight path and flew direct over Washington DC. At 0945LT, the aircraft crashed on the southwest side of the Pentagon building. The aircraft disintegrated on impact and all 64 occupants were killed. The terrorist attacks of September 11, 2001 are under the jurisdiction of the Federal Bureau of Investigation. The Safety Board provided requested technical assistance to the FBI, and this material generated by the NTSB is under the control of the FBI. The Safety Board does not plan to issue a report or open a public docket.

The Boeing 767 departed Boston-Logan Airport at 0814LT on a regular schedule service to Los Angeles, carrying 56 passengers and a crew of nine. Few minutes later, the aircraft was hijacked by terrorists who modified the flight path and flew direct over New York. At 0903LT, the aircraft struck the South Tower of the World Trade Center, between 78th and 84th floor. The aircraft disintegrated on impact and all 65 occupants were killed. The tower later collapsed. The terrorist attacks of September 11, 2001 are under the jurisdiction of the Federal Bureau of Investigation. The Safety Board provided requested technical assistance to the FBI, and this material generated by the NTSB is under the control of the FBI. The Safety Board does not plan to issue a report or open a public docket.

The Boeing 767 departed Boston-Logan at 0759LT on a regular schedule service to Los Angeles, carrying 81 passengers and a crew of 11. Few minutes later, the aircraft was hijacked by terrorists who modified the flight path and flew direct over New York. At 0845LT, the aircraft struck the North Tower of the World Trade Center, between 94th and 99th floor. The aircraft disintegrated on impact and all 92 occupants were killed. The tower later collapsed. The terrorist attacks of September 11, 2001 are under the jurisdiction of the Federal Bureau of Investigation. The Safety Board provided requested technical assistance to the FBI, and this material generated by the NTSB is under the control of the FBI. The Safety Board does not plan to issue a report or open a public docket.

After takeoff, the pilot reported "an engine problem," but did not elaborate. A witness on the ground saw that the left engine was trailing smoke, but the engine was still operating, and did not sound like it was "missing". When asked by the tower controller if he required assistance, the pilot answered "no". The controller cleared the pilot for left traffic to a landing, and provided the current weather. There were no further transmissions from the pilot. Smoothed radar tracking data revealed that the airplane turned toward a left downwind, and leveled off at 1,400 feet msl (about 1,050 feet agl) and 156 knots. During the next 14 seconds, the airplane descended to 1,100 feet and increased airspeed to 173 knots. Then radar contact was lost. Witnesses observed the airplane variously in a right snap roll and a left wingover, followed by a sharp dive to the ground. The airplane had just undergone maintenance. During maintenance, unused oil was found in the left engine cowling, which the pilot admitted he had previously spilled. Following maintenance, the pilot was observed adding 3 additional quarts of oil to the left engine. The engine oil dipsticks were calibrated on both sides, with each side pertaining to the oil level in a specific engine. The side for the right engine was calibrated to read 1 3/4 quarts lower than the left engine. The airplane's wreckage was fragmented. No evidence of mechanical defect was found, nor was there any evidence of an extreme out-of-trim condition. There was also no evidence of engine failure, detonation, or pre-impact failure. The pilot held an airline transport pilot certificate. He reported 3,210 hours of flight time to the operator, and had recently been cleared to fly the airplane on 14 CFR Part 91 flights. The flight to the maintenance facility was the pilot's first solo flight in the airplane. An autopsy of the pilot revealed the presence of a prostate adenocarcinoma; however, according to his physician, the pilot was unaware of it.

The captain and the first officer were landing a short takeoff and landing (STOL) cargo airplane on a private, dirt and gravel surface runway. The airplane was configured for landing with 40 degrees of flaps. During the landing approach, variations in indicated airspeed and ground speed indicated windshear conditions. About 100 to 200 feet above the ground, the airplane encountered a downdraft and began to drift to the right of the runway centerline. The captain said she increased engine power and applied full left aileron and rudder, but could not gain directional or pitch control of the airplane. The right wing struck trees, short of the runway threshold, increasing the airplane's right yaw. The captain said that as the airplane neared the ground, she pulled the engine throttles off. The airplane struck the ground with the right main landing gear and right front portion of the fuselage. The airplane then pivoted to the right, 180 degrees from the approach heading. The owner of the airport reported that wind conditions from the east may produce downdrafts in the area of runway 05. He indicated that at the time of the accident, the wind was blowing from the east about 15 knots. The first officer reported the captain appeared to be attempting to maintain a stabilized approach angle by varying the pitch attitude of the airplane. A review of company training literature revealed that the airplane is especially sensitive to slight wind shear, and wind gusts as low as 5 knots when operating at low airspeeds. Pilots are cautioned that when flying the aircraft at low speeds, a large application of the aileron control may be required to maintain wings level. During gusty wind conditions, the threshold airspeed should be increased by one-half the gust factor, and any lateral displacement should be corrected rapidly. If a wing is allowed to drop beyond corrective action of full aileron, power should be increased immediately to regain level flight.

The airplane sustained substantial damage on impact with terrain and objects after traveling off the end of the runway during a main wheels up landing. The captain reported that prior to takeoff, he closed the cargo door and the copilot confirmed the door light was out. After takeoff at an altitude of about 600 feet, the cockpit door popped open and the crew noticed the cargo door was open. The captain elected to return to land. The captain reported he requested repeatedly for gear and flaps extension, but the copilot was late in doing so and it "caused us to overshoot the runway centerline." The copilot then began calling for a go around/missed approach at which time he raised the gear and the retracted some of the flaps. The copilot reported the captain continued to descend toward the runway and overshot the runway centerline to the right. The copilot reported that at this time he lowered the gear. The nose gear extended prior to touchdown, however the main gear did not. The airplane touched down approximately 1/2 way down the runway and traveled off the end. A witness reported noticing that the exterior door latch was not down as the airplane taxied to the runway.

During an aerial fire suppression mission for the California Department of Forestry (CDF), two Grumman TS-2A airplanes, operating as Tanker 92 (N442DF) and Tanker 87 (N450DF), collided in flight while in a holding pattern awaiting a retardant drop assignment on the fire. All of the airplanes fighting the fire were TS-2A's, painted in identical paint schemes. The Air Tactical Group Supervisor (AirTac) was orbiting clockwise 1,000 feet above the tankers, who were in a counterclockwise orbit at 3,000 feet mean sea level (msl). The pilots of both aircraft involved in the collision had previously made several drops on the fire. Records from the Air Tac show that Tankers 86, 91, and 92 were in orbit, and investigation found that Tanker 87 was inbound to enter the orbit after reloading at a nearby airport base. AirTac would write down the tanker numbers as they made their 3-minutes-out call, and usually ordered their drops in the same order as their check-in. The AirTac's log recorded the sequence 86, 91, 21, and 92. The log did not contain an entry for Tanker 87. Other pilots on frequency did not recall hearing Tanker 87 check in. Based on clock codes with 12-o'clock being north, the tankers were in the following approximate positions of the orbit when the collision occurred. Tanker 92 was at the 2-o'clock position; Tanker 86 was turning in at the 5-o'clock position; and Tanker 91 was in the 7-o'clock position. The AirTac's log indicated that Tanker 92 was going to move up in sequence and follow Tanker 86 in order to drop immediately after him. Post accident examination determined that Tanker 92's flaps were down, indicating that the pilot had configured the airplane for a drop. Tanker 92 swung out of the orbit wide (in an area where ground witnesses had not seen tankers all day) to move behind Tanker 86, and the pilot would likely have been focusing on Tanker 86 out of his left side window. Tanker 87 was on line direct to the center of the fire on a path that witnesses had not observed tankers use that day. Reconstruction of the positions of the airplanes disclosed that Tankers 86 and 91 would have been directly in front of Tanker 87, and Tanker 92 would have been wide to his left. Ground witnesses said that Tanker 87 had cleared a ridgeline just prior to the collision, and this ridgeline could have masked both collision aircraft from the visual perspective of the respective pilots. The right propeller, engine, and cockpit of Tanker 92 contacted and separated the empennage of Tanker 87. The propeller chop was about 47 degrees counterclockwise to the longitudinal axis of Tanker 87 as viewed from the top. The collision appeared to have occurred about 2,500 feet, which was below orbit altitude. CDF had no standard operating manual, no established reporting or entry point for the holding orbits, and a tanker could enter any point of the orbit from any direction. While no standardized procedures were encoded in an operating manual, a CDF training syllabus noted that a tanker was not to enter an orbit until establishing positive radio contact with the AirTac. The entering tanker would approach 1,000 feet below AirTac's altitude and stay in a left orbit that was similar to a salad bowl, high and wide enough to see and clear all other tankers until locating the tanker that it was to follow, then adjust speed and altitude to fall in behind the preceding airplane.