Bethel

The approach to Saint Mary's Airport was initiated in marginal weather conditions. On short final, the single engine airplane crashed about 800 metres short of runway and was destroyed. All four occupants were killed. The airplane was completing a taxi flight from Bethel.

The pilot was conducting a scheduled air taxi flight with five passengers onboard. Shortly after departure, the pilot began to smell an electrical burn odor, and he elected to return to the airport. About 1 minute later, the electrical burn smell intensified, which was followed by visible smoke in the cockpit, and the pilot declared an emergency to the tower. After landing and all the passengers had safely departed the airplane, heavy smoke filled the cockpit and passenger compartment, and the pilot saw a candle-like flame just behind the pilot and co-pilot seats, just beneath the floorboards of the airplane. Moments later, the airplane was engulfed in flames. Postaccident examination of the airframe revealed the origin of the fire to be centered behind the pilot’s row of seats, where a wire harness was found improperly installed on top of the aft fuel line from the left tank. Examination of the wire harness found a range of thermal and electrical damage consistent with chafing from the fuel line. It is likely that the installation of the wire harness permitted contact with the fuel line, which resulted in chafing, arcing, and the subsequent fire.

The commercial pilot was conducting a visual flight rules scheduled passenger flight with five passengers. During the return leg to the company’s base airport, the pilot requested, and was given clearance to, a short gravel runway of 1,858 ft that terminated at parallel cross-runways and had inbound airplanes. The wind was reported as variable at 3 knots, and the outside air temperature was 88°F which was 25° warmer than usual. The pilot stated that he conducted a steeper than normal approach and performed a normal 30° flap landing flare; however, the airplane floated halfway down the runway. He initiated a go-around by advancing the throttle to takeoff power and retracting the flaps to 20° as the main landing gear briefly touched down. Automatic dependent surveillance-broadcast (ADS-B) data indicated that the airplane arrived 0.1 mile from the runway threshold at 149 ft above ground level (agl) and 110 knots of ground speed, which was 32 knots faster than the short field landing approach speed listed in the pilot operating handbook. A witness in the air traffic control tower (the ground controller) stated that the airplane “bled off a lot of airspeed,” during the landing attempt and climbed out in a very flat profile. The tower local controller stated that after liftoff, the airplane’s right wing dropped and the airplane appeared to be turning right into conflicting landing traffic, so he twice instructed the airplane to “left turn out immediately.” The pilot stated that he attempted to comply with the tower controller’s instruction, but when he applied left aileron, the airplane appeared to stall, rolled rapidly right, and descended in a right-wing-low attitude. It subsequently impacted the surface between runways. A postimpact fire ensued, and the pilot helped the passengers egress. The airplane was destroyed by postimpact fire. Given the evidence, it is likely that the pilot decided to land on the short runway to expedite the arrival and did not perform an appropriate short field landing approach, which resulted in excessive airspeed and altitude over the runway threshold, a long landing flare, rapid deceleration, and a self-initiated go-around from a slow airspeed. Had the pilot initiated the go-around as he approached the runway with indications of an unstable visual approach, the airspeed would have been well above stall speed, which would have allowed for the desired positive climb out on runway heading. The pilot likely attempted to comply with the tower local controller’s urgent commands to turn while the airplane was near the limit of performance (the temperature was about 25 degrees warmer than average, which would have resulted in a higher density altitude than the pilot was accustomed to and degraded aircraft and engine performance). The pilot’s maneuvering resulted in the exceedance of the critical angle-of-attack of the high wing (right wing) during the left turn, and an aerodynamic stall.

The pilot departed on a postmaintenance test flight during day visual meteorological conditions. According to the operator, the purpose of the flight was to break in six recently installed engine cylinders, and the flight was expected to last 3.5 hours. Recorded automatic dependent surveillance-broadcast data showed that the airplane was operating at altitudes of less than 500 ft mean sea level for the majority of the flight. The data ended about 3 hours after takeoff with the airplane located about 23 miles from the accident site. There were no witnesses to the accident, which occurred in a remote area. When the airplane did not return, the operator reported to the Federal Aviation Administration that the airplane was overdue. Searchers subsequently discovered the fragmented wreckage submerged in a swift moving river, about 40 miles southeast of the departure/destination airport. Postmortem toxicology tests identified 21% carboxyhemoglobin (carbon monoxide) in the pilot's blood. The pilot was a nonsmoker, and nonsmokers normally have no more than 3% carboxyhemoglobin. There was no evidence of postimpact fire; therefore, it is likely that the pilot's elevated carboxyhemoglobin level was from acute exposure to carbon monoxide during the 3 hours of flight time before the accident. As the pilot did not notify air traffic control or the operator's home base of any problems during the flight, it is unlikely that he was aware that there was carbon monoxide present. Early symptoms of carbon monoxide exposure may include headache, malaise, nausea, and dizziness. Carboxyhemoglobin levels between 10% and 20% can result in confusion, impaired judgment, and difficulty concentrating. While it is not possible to determine the exact symptoms the pilot experienced, it is likely that the pilot had symptoms that may have been distracting as well as some degree of impairment in his judgment and concentration. Given the low altitudes at which he was operating the airplane, he had little margin for error. Thus, it is likely that the carbon monoxide exposure adversely affected the pilot's performance and contributed to his failure to maintain clearance from the terrain. According to the operator, the airplane had a "winter heat kit" installed, which modified the airplane's original cabin heat system. The modification incorporated an additional exhaust/heat shroud system designed to provide increased cabin heat during wintertime operations. Review of maintenance records revealed that the modification had not been installed in accordance with Federal Aviation Administration field approval procedures. Examination of the recovered wreckage did not reveal evidence of any preexisting mechanical anomalies that would have precluded normal operation of the airplane. Examination of the airplane's right side exhaust/heat exchanger did not reveal any leaks or fractures that would have led to carbon monoxide in the cabin. Because the left side exhaust/heat exchanger was
not recovered, it was not possible to determine whether it was the source of the carbon monoxide.

The check airman was conducting the first company training flight for the newly hired second-in-command (SIC). Automatic Dependent Surveillance-Broadcast (ADS-B) data showed that, after departure, the airplane began a series of training maneuvers, consistent with normal operations. About 21 minutes into the flight, when the airplane was about 3,400 ft mean sea level, it began a steep descent and subsequently impacted terrain. An airplane performance study showed that the airplane reached a nose-down pitch of about -40 degrees and that the descent rate reached about 16,000 ft per minute. Numerous previous training flights conducted by the check airman were reviewed using archived ADS-B data and interviews with other pilots. The review revealed that the initial upset occurred during a point in the training when the check airman typically simulated an in-flight emergency and descent. Postaccident examination for the airframe and control surfaces showed that the airplane was configured for cruise flight at the time of the initial upset. Examination of the primary and secondary flight control cables indicated that the cables were all intact at the time of impact. Trim actuator measurements showed an abnormal trailing-edge-up, nose-down configuration on both trim tabs. The two elevator trim actuator measurements were inconsistent with each other, indicating that one of the actuators was likely moved during the wreckage recovery. Based on the supporting data, it is likely that one of the actuators indicated the correct trim tab position at the time of impact. Simulated airplane performance calculations showed that, during a pitch trim excursion, the control forces required to counter an anomaly increases to unmanageable levels unless the appropriate remedial procedures are quickly applied. Given the simulated airplane performance calculations, the trim actuator measurements, and the check airman's known training routine, it is likely that the check airman simulated a pitch trim excursion and that the SIC, who lacked experience in the airplane type, did not appropriately respond to the excursion. The check airman did not take remedial action and initiate the recovery procedure in time to prevent the control forces from becoming unmanageable and to ensure that recovery from the associated dive was possible.

The pilot departed on a scheduled commuter flight at night from an unlit, rough and uneven snow-covered runway with five passengers and baggage. During the takeoff roll, the airplane bounced twice and became airborne, but it failed to climb. As the airplane neared the departure end of the runway, it began to veer to the left, and the pilot applied full right aileron, but the airplane continued to the left as it passed over the runway threshold. The airplane subsequently settled into an area of snow and tundra-covered terrain about 100 yards south of the runway threshold and nosed over. Official sunset on the day of the accident was 48 minutes before the accident, and the end of civil twilight was one minute before the accident. The Federal Aviation Administration's (FAA) Airport/Facility Directory, Alaska Supplement listing for the airport, includes the following notation: "Airport Remarks - Unattended. Night operations prohibited, except rotary wing aircraft. Runway condition not monitored, recommend visual inspection prior to using. Safety areas eroded and soft. Windsock unreliable." A postaccident examination of the airplane and engine revealed no mechanical anomalies that would have precluded normal operation. Given the lack of mechanical deficiencies with the airplane's engine or flight controls, it is likely the pilot failed to maintain control during the takeoff roll and initial climb after takeoff.

On September 2, 2011, about 1335 Alaska daylight time, a Cessna 208B airplane, N207DR, and a Cessna 207 airplane, N73789, collided in midair about 9 miles north of Nightmute, Alaska. Both airplanes were being operated as charter flights under the provisions of 14 Code of Federal Regulations (CFR) Part 135 in visual meteorological conditions when the accident occurred. The Cessna 208B was operated by Grant Aviation Inc., Anchorage, Alaska, and the Cessna 207 was operated by Ryan Air, Anchorage, Alaska. Visual flight rules (VFR) company flight following procedures were in effect for each flight. The sole occupant of the Cessna 208B, an airline transport pilot, sustained fatal injuries. The sole occupant of the Cessna 207, a commercial pilot, was uninjured. The Cessna 208B was destroyed, and the Cessna 207 sustained substantial damage. After the collision, the Cessna 208B descended uncontrolled and impacted tundra-covered terrain, and a postcrash fire consumed most of the wreckage. The Cessna 207’s right wing was damaged during the collision and the subsequent forced landing on tundra-covered terrain. Both airplanes were based at the Bethel Airport, Bethel, Alaska, and were returning to Bethel at the time of the collision. The Cessna 208B departed from the Toksook Bay Airport, Toksook Bay, Alaska, about 1325, and the Cessna 207 departed from the Tununak Airport, Tununak, Alaska. During separate telephone conversations with the National Transportation Safety Board (NTSB) investigator-in-charge on September 2, the chief pilot for Ryan Air, as well as the director of operations for Grant Aviation, independently reported that both pilots had a close personal relationship. During an initial interview with the NTSB IIC on September 3, in Bethel, the pilot of the Cessna 207 reported that both airplanes departed from the neighboring Alaskan villages about the same time and that both airplanes were en route to Bethel along similar flight routes. She said that, just after takeoff from Tununak, she talked with the pilot of the Cessna 208B on a prearranged, discreet radio frequency, and the two agreed to meet up in-flight for the flight back to Bethel. She said that, while her airplane was in level cruise flight at 1,200 feet above mean sea level (msl), the pilot of the Cessna 208B flew his airplane along the left side of her airplane, and they continued to talk via radio. She said that the pilot of the Cessna 208B then unexpectedly and unannounced climbed his airplane above and over the top of her airplane. She said that she immediately told the pilot of the Cessna 208B that she could not see him and that she was concerned about where he was. She said that the Cessna 208B pilot then said, in part: "Whatever you do, don't pitch up." The next thing she recalled was moments later seeing the wings and cockpit of the descending Cessna 208B pass by the right the side of her airplane, which was instantaneously followed by an impact with her airplane’s right wing. The Cessna 207 pilot reported that, after the impact, while she struggled to maintain control of her airplane, she saw the Cessna 208B pass underneath her airplane from right-to-left, and it began a gradual descent, which steepened as the airplane continued to the left and away from her airplane. She said that she told the pilot of the Cessna 208B that she thought she was going to crash.She said that the pilot of the Cessna 208B simply stated, “Me too.” She said that she watched as the Cessna 208B continued to descend, and then it entered a steep, vertical, nose-down descent before it collided with the tundra-covered terrain below. She said that a postcrash fire started instantaneously upon impact. Unable to maintain level cruise flight and with limited roll control, the Cessna 207 pilot selected an area of rolling, tundra-covered terrain as a forced landing site. During touchdown, the airplane’s nosewheel collapsed, and the airplane nosed down. The Cessna 207’s forced landing site was about 2 miles east of the Cessna 208B’s accident site.

A Cessna 208B and a Cessna 207 collided in flight in daylight visual meteorological conditions. The Cessna 208B and the Cessna 207 were both traveling in an easterly direction. According to the Cessna 207 pilot, the airplanes departed from two neighboring remote Alaskan villages about the same time, and both airplanes were flying along similar flight routes. While en route, the Cessna 207 pilot talked with the Cessna 208B pilot on a prearranged, discreet radio frequency, and the two agreed to meet up in flight for the return to their home airport. The Cessna 207 pilot said that the pilot of the Cessna 208B flew his airplane along the left side of her airplane while she was in level cruise flight at 1,200 feet mean sea level and that they continued to talk via the radio. Then, unexpectedly and unannounced, the pilot of the Cessna 208B maneuvered his airplane above and over the top of her airplane. She said that she immediately told the Cessna 208B pilot that she could not see him and that she was concerned about where he was. She said that the Cessna 208B pilot then said, in part: "Whatever you do, don't pitch up." The next thing she recalled was seeing the wings and cockpit of the descending Cessna 208B pass by the right side of her airplane, which was instantly followed by an impact with her airplane's right wing. She said that after the collision, the Cessna 208B passed underneath her airplane from right-to-left before beginning a gradual descent that steepened as the airplane continued to the left. It then entered a steep, vertical, nose-down descent before colliding with the tundra-covered terrain below followed by a postcrash fire. Unable to maintain level cruise flight, the Cessna 207 pilot selected an area of rolling, tundra-covered terrain as a forced landing site. An examination of both airplanes revealed impact signatures consistent with the Cessna 208B's vertical stabilizer impacting the Cessna 207's right wing. A portion of crushed and distorted wreckage, identified as part of the Cessna 208B's vertical stabilizer assembly, was found embedded in the Cessna 207's right wing. The Cessna 208B's severed vertical stabilizer and rudder were found about 1,000 feet west of the Cessna 208B's crash site.

Shortly after take off from runway 20, aircraft hit tree tops, stalled and crashed in a wooded area near the airport. Both passenger were slightly injured while the pilot was seriously injured. Aircraft was damaged beyond repair. The director of operations for the operator stated that soft field conditions and standing water on the runway slowed the airplane during the takeoff roll. The airplane did not lift off in time to clear trees at the end of the runway and sustained substantial damage to both wings and the fuselage when it collided with the trees. The pilot reported that he used partial power at the beginning of the takeoff roll to avoid hitting standing water on the runway with full power. After passing most of the water, he applied full power, but the airplane did not accelerate like he thought it would. He recalled the airplane being in a nose-high attitude and the main wheels bouncing several times before the airplane impacted the trees at the end of the runway.

The airline transport pilot was on a Title 14, CFR Part 135 passenger flight. The pilot said during cruise flight he heard a loud bang, and the engine started running rough. He said he diverted to the nearest airport, but the engine quit completely, and he was unable to reach the runway. The airplane subsequently collided with terrain, sustaining substantial damage to both wings and the fuselage. An examination of the engine revealed that a locking screw had backed out of one of the anti-vibration counterweights on the crankshaft, scoring the interior back surface of the engine case. The unsecured counterweight then moved from its position in the crankshaft, and was likely struck by the engine's master rod, which shattered the weight, and liberated it from its normal location. The liberated counterweight was struck by internal moving parts, creating several component failures, and ultimately an engine seizure.