Flight

The single engine aircraft departed Surkhet Airport at 0612LT on a cargo flight to Simikot. At 0627LT, the crew made his last radio transmission with Nepalgunj Tower. About 18 minutes later, while cruising by night at an altitude of 12,800 feet, the airplane struck the slope of a mountain located near the Simikot Pass, some 12 km from Simikot Airport. The airplane disintegrated on impact and both crew members were killed.

The single engine aircraft crashed in unknown circumstances in a wooded and hilly terrain located near Tuzantán. The airplane was totally destroyed by a post crash fire and all three occupants were killed. According to Mexican Authorities, the crew was completing an illegal flight.

Before the air taxi flight, the commercial pilot obtained a weather briefing via the company computer system and reviewed the weather information with the company chief pilot. The pilot stated that based on the computer briefing, which did not include icing conditions, he was aware of the forecasted weather conditions along the route of flight and at the intended destination. However, the briefing was incomplete as it did not contain any in-flight weather advisories, which would have alerted the pilot of moderate icing conditions expected over the flight route in the form of AIRMET Zulu. After takeoff and during the climb to 12,000 ft mean sea level (msl), the airplane encountered light rime ice, and the pilot activated the de-ice equipment with no issues noted. After hearing reports of better weather at a lower altitude, the pilot requested a descent to between 5,000 and 6,000 ft. During the descent to 6,000 ft msl and with the airplane clear of ice, the airplane encountered light to moderate icing conditions. The pilot considered turning back to another airport but could not get clearance until the airplane was closer to his destination. Shortly thereafter, the pilot stated that it felt “like a sheet of ice fell on us” as the airplane encountered severe icing conditions. The pilot applied full engine power in an attempt to maintain altitude. The airplane exited the overcast cloud layer about 500 ft above ground level. The pilot chose to execute an off-airport emergency landing because the airplane could not maintain altitude. During the landing, the landing gear separated; the airplane came to rest upright and sustained substantial damage to the wings and fuselage. The pilot reported that there were no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation and that the airplane was within its maximum gross weight. Structural icing was observed on the airframe after the landing. Based on the weather information, which indicated the probability of icing between 5,000 and 9,000 ft over the region and a high threat of supercooled large droplets between 5,000 and 7,000 ft, it is likely that the airplane, which was equipped for flight in icing conditions, inadvertently encountered severe icing conditions consistent with supercooled large droplets, which resulted in structural icing that exceeded the airplane’s capabilities to maintain altitude.

The instrument rated private pilot was drinking alcohol before he arrived at the airport. Before the flight, he did not obtain a weather briefing or file an instrument flight rules flight plan for the flight that was conducted in instrument meteorological conditions. The pilot performed a 3-minute preflight inspection of the airplane and departed with a tailwind (even though he had initially taxied the airplane to the runway that favored the wind) and without communicating on the airport Unicom frequency. After departure, the airplane climbed to a maximum altitude of 11,500 feet mean sea level (msl), and then the airplane descended to 4,300 ft msl (which was 1,400 ft below the minimum safe altitude for the destination airport) and remained at that altitude for 9 minutes. Afterward, the airplane began a descending left turn, and radar contact was lost at 2054. The pilot did not talk to air traffic control during the flight and while operating in night instrument meteorological conditions. During the flight, the airplane flew through a line of severe thunderstorms with heavy rain, tornados, hail, and multiple lightning strikes. Before the airplane's descending left turn began, it encountered moderate-to-heavy rain. The airplane's high descent rate of at least 6,000 ft per minute and impact with a mountain that was about 450 ft from the last radar return, the damage to the airplane, and the distribution of the wreckage were consistent with a loss of control and a high-velocity impact. Examination of the airplane revealed no evidence of any preimpact mechanical anomalies. Based on the reported weather conditions at the time the flight, the pilot likely completed the entire flight in night instrument meteorological conditions. His decision to operate at night in an area with widespread thunderstorms and reduced visibility were conducive to the development of spatial disorientation. The airplane's descending left turn and its high-energy impact were consistent with the known effects of spatial disorientation. The pilot was not aware of the conditions near and at the destination airport because he failed to obtain a weather briefing and was not communicating with air traffic control. Also, the pilot's decision to operate an airplane within 8 hours of consuming alcohol was inconsistent with the Federal Aviation Administration's regulation prohibiting such operations, and the level of ethanol in the pilot's toxicology exceeded the level allowed by the regulation. Overall, the pilot's intoxication, combined with the impairing effects of cetirizine, affected his judgment; contributed to his unsafe decision-making; and increased his susceptibility to spatial disorientation, which resulted in the loss of control of the airplane.

Few minutes after takeoff from Pelagiada, the pilot informed ATC about the failure of the right engine while the left engine lost power. The pilot completed an emergency belly landing in an open field located near Pelagiada, about 20 km north of Stavropol. The aircraft was damaged beyond repair and the pilot escaped uninjured.

A Turkish Challenger 604 corporate jet impacted a mountain near Shahr-e Kurd in Iran, killing all 11 on board. The aircraft departed Sharjah, UAE at 13:11 UTC on a flight to Istanbul, Turkey. The aircraft entered Tehran FIR fifteen minutes later and the Tehran ACC controller cleared the flight to climb to FL360 according to its flight plan. About 14:32, the pilot requested FL380, which was approved. Before reaching that altitude, the left and right airspeeds began to diverge by more than 10 knots. The left (captain's) airspeed indicator showed an increase while the right hand (copilot's) airspeed indicator showed a decrease. A caution aural alert notified the flight crew of the difference. Remarks by the flight crew suggested that an 'EFIS COMP MON' caution message appeared on the EICAS. As the aircraft was climbing, the crew reduced thrust to idle. Approximately 63 seconds later, while approaching FL380, the overspeed aural warning (clacker) began to sound, indicating that the indicated Mach had exceeded M 0.85. Based on the Quick Reference Handbook (QRH) of the aircraft, the pilot flying should validate the IAS based on the aircraft flight manual and define the reliable Air Data Computer (ADC) and select the reliable Air Data source. The pilot did not follow this procedure and directly reduced engine power to decrease the IAS after hearing the clacker. The actual airspeed thus reached a stall condition. The copilot tried to begin reading of the 'EFIS COMP MON' abnormal procedure for three times but due to pilot interruption, she could not complete it. Due to decreasing speed, the stall aural warning began to sound, in addition to stick shaker and stick pusher activating repeatedly. The crew then should have referred to another emergency procedure to recover from the stall condition. While the stick pusher acted to pitch down the aircraft to prevent a stall condition, the captain was mistakenly assumed an overspeed situation due to the previous erroneous overspeed warning and pulled on the control column. The aircraft entered a series of pitch and roll oscillations. The autopilot was disengaged by the crew before stall warning, which ended the oscillations. Engine power began to decrease on both sides until both engines flamed out in a stall condition. From that point on FDR data was lost because the electric bus did not continue to receive power from the engine generators. The CVR recording continued for a further approximately 1 minute and 20 seconds on emergency battery power. Stall warnings, stick shaker and stick pusher activations continued until the end of the recording. The aircraft then impacted mountainous terrain. Unstable weather conditions were present along the flight route over Iran, which included moderate up to severe turbulence and icing conditions up to 45000ft. These conditions could have caused ice crystals to block the left-hand pitot tube. It was also reported that the aircraft was parked at Sharjah Airport for three days in dusty weather condition. Initially the pitot covers had not been applied. The formation of dust inside the pitot tube was considered another possibility.

The pilot in the multi-engine, retractable landing gear airplane reported that, during an instrument flight rules cross-country flight, about 5,000 ft above mean sea level, the left engine surged several times and he performed an emergency engine shutdown. Shortly afterward, the right engine lost power. During the emergency descent, the airplane struck treetops, and landed hard in a field with the landing gear retracted. The airplane sustained substantial damage to both wings, the engine mounts, and the lower fuselage. The pilot reported that he had requested 200 gallons of fuel from his home airport fixed base operator, but they did not fuel the airplane. The pilot did not check the fuel quantity during his preflight inspection. According to the Federal Aviation Administration Airplane Flying Handbook, Chapter 2, page 2-7, pilots must always positively confirm the fuel quantity by visually inspecting the fuel level in each tank. The pilot reported that there were no mechanical malfunctions or failures with the airplane that would have precluded normal operation.

The airline transport pilot and two passengers departed in the twin-engine, pressurized airplane on a business flight in night instrument meteorological conditions. Shortly after takeoff, the airplane began to deviate from its assigned altitude and course. The controller queried the pilot, who responded that the airplane was "… a little out of control." After regaining control of the airplane, the pilot reported that he had experienced a "trim issue." The airplane continued on course and, about 13 minutes later, the pilot again reported a trim malfunction and said that he was having difficulty controlling the airplane. The flight's heading and altitude began to deviate from the course for the last 8 minutes of radar data and became more erratic for the last 2 minutes of radar data; radar and radio communication were subsequently lost at an altitude of about 18,300 ft in the vicinity of the accident site. Several witnesses reported hearing the airplane flying overhead. They all described the airplane as being very loud and that the engine sound was continuous up until they heard the impact. The airplane impacted a field in a relatively level attitude at high speed. The wreckage was significantly fragmented and the wreckage path extended about 1/4 mile over several fields. Examination of the available airframe and engine components revealed no anomalies that would have precluded normal operation of the airplane. The accident airplane was equipped with elevator, rudder, and aileron trim systems; however, not all components of the trim system and avionics were located or in a condition allowing examination. Although the airplane was equipped with an electric elevator trim and autopilot that could both be turned off in an emergency, the investigation could not determine which trim system the pilot was reportedly experiencing difficulties with. It is likely that the pilot was unable to maintain control of the airplane as he attempted to address the trim issues that he reported to air traffic control.

Iranian ATR72 aircraft registered EP-ATS operated by Iran Aseman Airlines was assigned to perform a domestic scheduled passenger flight from Tehran to Yasuj on 07:55 local time. The aircraft took off from Tehran Mehrabad International Airport (0III) at 04:35 UTC. (08:05 LMT) and the flight was the first flight of the day for aircraft and the crew. The cruise flight was conducted at FL210 on airway W144 and no abnormal situation was reported by the crew and the flight was continued on Tehran ACC frequency till the time the first officer requested latest weather information of the destination by contact to Yasuj tower then requested to leave FL210 to FL170 from Tehran ACC. When the aircraft was descending to FL170 and crew calling YSJ tower the aircraft descending was continued to altitude of 15000 ft. The aircraft was approved to join overhead of the airport and perform “circling NDB approach “to land on RWY 31 at the destination aerodrome. Finally the aircraft collided with a peak lee of DENA Mountains about 8.5 miles at North far from the airport and involved accident on 06:01 UTC. The aircraft was completely destroyed as a result of collision with the mountain at the altitude of approximately 13,300 ft.

While completing a training mission, the airplane crashed in unknown circumstances near the Zhengchang village, in the Guizhou Province. The PLA Air Force Y-8GX4 Electronic Intelligence (ELINT) aircraft, registered 30513, was assigned to the PLAAF 20th Special Missions Division. The Y-8G fleet of the division is reportedly based close to the crash site. The airplane was totally destroyed by impact forces and a post crash fire and all 12 occupants were killed.