Mountains

The captain and first officer were conducting an international cargo flight in the twin-engine turboprop airplane. After about 40 minutes of flight during night visual meteorological conditions, an air traffic controller cleared the airplane for a descent to 7,000 ft and then another controller further cleared the airplane for a descent to 3,000 ft and told the flight crew to expect an ILS (instrument landing system) approach. During the descent, about 7,300 ft and about 290 kts, the airplane entered a shallow left turn, followed by a 45-degree right turn and a rapid, uncontrolled descent, during which the airplane broke up about 1,500 ft over uneven terrain. The moderately loaded cargo airplane was not equipped with a flight data recorder or cockpit voice recorder (CVR) (although it previously had a CVR in its passenger configuration) nor was it required by Federal Aviation Administration (FAA) regulations. There were also no avionics on board with downloadable or nonvolatile memory. As a result, there was limited information available to determine what led to the uncontrolled descent or what occurred as the flight crew attempted to regain control of the airplane. Also, although the first officer was identified in FAA-recorded radio transmissions several minutes before the loss of control and it was company policy that the pilot not flying make those transmissions, it could not be determined who was at the controls when either the loss of control occurred or when the airplane broke up. There was no evidence of any in-flight mechanical failures that would have resulted in the loss of control, and the airplane was loaded within limits. Evidence of all flight control surfaces was confirmed, and, to the extent possible, flight control continuity was also confirmed. Evidence also indicated that both engines were operating at the time of the accident, and, although one of the four propeller blades from the right propeller was not located after separating from the fractured hub, there was no evidence of any preexisting propeller anomalies. The electrically controlled pitch trim actuator did not exhibit any evidence of runaway pitch, and measurements of the actuator rods indicated that the airplane was trimmed slightly nose low, consistent for the phase of flight. Due to the separation of the wings and tail, the in-flight positions of the manually operated aileron and rudder trim wheels could not be determined. Other similarly documented accidents and incidents generally involved unequal fuel burns, which resulted in wing drops or airplane rolls. In one case, the flight crew intentionally induced an excessive slide slip to balance fuel between the wings, which resulted in an uncontrolled roll. However, in the current investigation, the fuel cross feed valve was found in the closed position, indicating that a fuel imbalance was likely not a concern of the flight crew. In at least two other events, unequal fuel loads also involved autopilots that reached their maximum hold limits, snapped off, and rolled the airplane. Although the airplane in this accident did not have an autopilot, historical examples indicate that a sudden yawing or rolling motion, regardless of the source, could result in a roll, nose tuck, and loss of control. The roll may have been recoverable, and in one documented case, a pilot was able to recover the airplane, but after it lost almost 11,000 ft of altitude. During this accident flight, it was likely that, during the descent, the flight crew did regain control of the airplane to the extent that the flight control surfaces were effective. With darkness and the rapid descent at a relatively low altitude, one or both crewmembers likely pulled hard on the yoke to arrest the downward trajectory, and, in doing so, placed the wings broadside against the force of the relative wind, which resulted in both wings failing upward. As the wings failed, the propellers simultaneously chopped through the fuselage behind the cockpit. At the same time, the horizontal stabilizers were also positioned broadside against the relative wind, and they also failed upward. Evidence also revealed that, at some point, the flight crew lowered the landing gear. Although it could not be determined when they lowered the gear, it could have been in an attempt to slow or regain control of the airplane during the descent. Although reasons for the loss of control could not be definitively determined, the lack of any preexisting mechanical anomalies indicates a likelihood of flight crew involvement. Then, during the recovery attempt, the flight crew's actions, while operating under the difficult circumstances of darkness and rapidly decreasing altitude, resulted in the overstress of the airplane.

The twin engine aircraft departed Monterrey-Del Norte Airport at 0820LT on a flight to Xalapa-El Lencero Airport, Veracruz. While cruising in marginal weather conditions, the airplane crashed in the Sierra Madre Oriental, near the summit of Mirador. The aircraft was destroyed by a post crash fire and both occupants were killed.

The single engine aircraft departed Loreto Airport at 0901LT on a flight to Ciudad Constitución, carrying 13 passengers and one pilot. Weather conditions were poor with limited visibility and heavy rain falls due to the presence of the tropical storm 'Octave'. Six minutes after takeoff, while cruising at an altitude of 3,900 feet, the airplane impacted the slope of a rocky mountain located in the Sierra de La Giganta. The wreckage was found two days later some 26 km west of Loreto. The aircraft disintegrated on impact and all 14 occupants were killed.

The aircraft departed Panama City-Marcos A. Gelabert Airport in the evening on an anti-narcotic survey flight over Colombia, carrying four passengers and two pilots, five US citizens and one Panamanian. En route, while cruising along the border between Panama and Colombia, the aircraft collided with trees and crashed on the slope of a wooded mountain, bursting into flames. All four passengers were killed and both pilots were seriously injured.

The aircraft departed the Dominican Republic for an international flight and no flight plan was filed. While cruising in the region of Jérémie, the twin engine aircraft hit a mountain some 30 km from Jérémie. The aircraft was destroyed by impact forces and a post-crash fire and both occupants were killed. According to Dominican Authorities, the owner of the plane, a businessman, leased it to a couple from Honduras who were certainly performing an illegal flight.

The pilot reported that the accident flight was his fourth flight and the third tour flight of the day in a float-equipped airplane. The weather had deteriorated throughout the day with lowering ceilings, light rain, and fog on the mountain ridges. The pilot said that when approaching a mountain pass, he initiated a climb by adding a “little bit” of flap (about 1 pump of the flap handle actuator) but did not adjust the engine power from the cruise power setting. He noted his airspeed at 80 knots, with a 200-feet-per-minute climb on the vertical speed indicator. He was having difficulty seeing over the cowling due to the nose-high attitude, when he suddenly noticed trees in his flight path. He initiated an immediate left turn; the airplane stalled, and began to drop, impacting the mountainous, tree-covered terrain. A passenger reported that the weather conditions at the time of the accident consisted of tufts of low clouds, and good visibility. They did not enter the clouds at any time during the flight. He reported that the airplane made a left turn, stalled, and then made a sharp left turn right before impact. The airplane seemed to be operating fine, and he heard no unusual sounds, other than the engine speed seemed to increase significantly right before impact. The pilot reported that there were no preaccident mechanical anomalies that would have precluded normal operation, and the postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.

During a cross-country instrument flight rules (IFR) flight, the air traffic controller cleared the pilot to begin his initial descent for landing and issued a heading change to begin the approach. The pilot acknowledged the altitude and heading change. One minute later, the controller noticed that the airplane's radar track was not tracking the assigned heading. The controller queried the pilot as to his intentions, and the pilot replied that he was in a spin. There were no further communications with the pilot. The wreckage was subsequently located in steep mountainous terrain. A study of the weather indicated widespread cloud cover in the area around the time of the accident. A witness near the accident site reported that he heard an airplane in a dive but could not see it due to the very dark clouds in the area. He heard the engine noise increase and decrease multiple times. It is likely that the pilot entered into the clouds and failed to maintain airplane control. The changes in the engine noise were most likely the result of the pilot's attempt to recover from the spin. About 8 months before the accident, the pilot completed the initial pilot training course in the accident airplane and was signed off for IFR currency; however, recent or current IFR experience could not be determined. Examination of the fragmented airplane and engines revealed no abnormalities that would have precluded normal operation.

On 3 May 2013, at approximately 1448 hours local time (L), a KC-135R, tail number 63-8877, assigned to the 22d Expeditionary Air Refueling Squadron, 376th Air Expeditionary Wing, Transit Center at Manas, Kyrgyz Republic, crashed in the foothills of mountains located 6 miles south of Chaldovar, Kyrgyz Republic. The mishap crew (MC), which consisted of the mishap pilot (MP), mishap co-pilot (MCP), and mishap boom operator (MBO), perished during the accident. The mishap aircraft (MA) exploded inflight, impacted the terrain at three main locations, and burned. The MA was completely destroyed with total loss to government property estimated at $66.3 million. Upon impact, approximately 228 cubic meters of soil were contaminated with jet fuel, and three distinct craters containing a burn pattern were created. The MA’s mission was to refuel coalition aircraft in Afghanistan and then return to the Transit Center at Manas. Immediately after takeoff, the MA experienced an unexpected rapid heading change from the direction of flight known as a crab. During climb, nearly continuous rudder hunting caused the MA’s nose to hunt slowly left and right about one degree in both directions. The MP commented on the lateral control challenges and possible series yaw damper (SYD) malfunction but continued the mission without turning off either the SYD or rudder power. Approximately nine minutes into the flight, the MA began a series of increasing yaw and roll oscillations known as a dutch roll, which was undiagnosed by the MC. The MCP attempted to decrease these oscillations using manual aileron controls, as well as two brief attempts with the autopilot. The manual corrective inputs kept the oscillations from growing. The autopilot use further exacerbated the situation, and the oscillations intensified. After the second autopilot use, the MP assumed control of the MA and used left rudder to start a left turn. A subsequent series of alternating small rudder inputs, caused by the MA’s dutch roll-induced acceleration forces varying the MP’s foot pressure on the rudder pedals, sharply increased the dutch roll oscillations. Within 30 seconds, the MP made a right rudder input to roll out of the turn, exacerbating the dutch roll condition. The cumulative effects of the malfunctioning SYD, coupled with autopilot use and rudder movements during the unrecognized dutch roll, generated dutch roll forces that exceeded the MA’s design structural limits. The tail section failed and separated from the aircraft, causing the MA to pitch down sharply, enter into a high-speed dive, explode inflight and subsequently impact the ground at approximately 1448L.
Crew:
Cpt Victoria Ann Pinckney,
Cpt Mark Tyler Voss,
T/Sgt Herman Mackey III.

On 27 April 2013, at approximately 1243 local time (L) in Afghanistan, an MC-12W, tail number 09-0676 impacted terrain 110 nautical miles northeast of Kandahar Airfield (KAF) while on a combat intelligence, surveillance, and reconnaissance (ISR) mission. The four crewmembers on board were the Mishap Mission Commander (MMC), Mishap Pilot (MP), Mishap Sensor Operator (MSO), and Mishap Tactical Systems Operator (MTSO). The four airmen were killed instantly on impact and the Mishap Aircraft (MA), valued at $19.8 million, was destroyed. The crew and MA were deployed to the 361st expeditionary Reconnaissance Squadron, 451st Air Expeditionary Wing, KAF, Afghanistan. The MA, callsign Independence 08, departed KAF at 1157L and entered orbit at 1229L. The MA encountered deteriorating weather in the orbit and was climbing from 20,000 to 23,000 feet mean sea level (MSL) at 1241L to fly above the weather when the mishap occurred. In addition, the crew had found an enemy combatant and was in the process of adjusting their orbit to enhance mission success.

Aircraft was destroyed when it impacted rising terrain about 10 miles east of Aleknagik, Alaska. The airplane was operated as Flight 51, by Alaska Central Express, Inc., Anchorage, Alaska, as an on demand cargo flight under the provisions of 14 Code of Federal Regulations (CFR) Part 135. The airline transport certificated captain and the commercial certificated first officer sustained fatal injuries. Instrument meteorological conditions were reported in the area at the time of the accident, and the airplane was operating on an instrument flight rules (IFR) flight plan. The flight had originally departed Anchorage about 0544, and made a scheduled stop at King Salmon, Alaska, before continuing on to the next scheduled stop, Dillingham, Alaska. According to Federal Aviation Administration (FAA) personnel, as the airplane approached Dillingham, the flight crew requested the RNAV GPS 19 instrument approach to the Dillingham Airport about 0757 from controllers at the Anchorage Air Route Traffic Control Center (ARTCC). The ARTCC specialist on duty subsequently granted the request by issuing the clearance, with instructions to proceed direct to the Initial Approach Fix (IAF) to begin the approach, and to maintain an altitude of 2,000 feet or above. A short time later the flight crew requested to enter a holding pattern at the IAF so that they could contact the Flight Service Station (FSS) for a runway conditions report, and the ARTCC specialist granted that request. The ARTCC specialist then made several attempts to contact the aircraft, but was unsuccessful and subsequently lost radar track on the aircraft. When the airplane failed to arrive at the Dillingham Airport, ARTCC personnel initiated a radio search to see if the airplane had diverted to another airport. Unable to locate the airplane, the FAA issued an alert notice (ALNOT) at 0835. Search personnel from the Alaska State Troopers, Alaska Air National Guard, and the U.S. Coast Guard, along with several volunteer pilots, were dispatched to conduct an extensive search effort. Rescue personnel aboard an Air National Guard C-130 airplane tracked 406 MHz emergency locater transmitter (ELT) signal to an area of mountainous terrain about 20 miles north of Dillingham, but poor weather prohibited searchers from reaching the site until the next morning. Once the crew of a HH-60G helicopter from the Air National Guard's 210th Air Rescue Squadron, Anchorage, Alaska, reached the steep, snow and ice-covered site, they confirmed that both pilots sustained fatal injuries.