Flight

The twin engine aircraft departed San Luis Potosí on a flight to Torreón with an intermediate stop in Ciudad Victoria, carrying five passengers and one pilot. At the end of the afternoon, while descending to Ciudad Victoria Airport, the pilot encountered poor weather conditions. Too low, the aircraft impacted trees and crashed in a hilly terrain located near Conrado Castillo. The wreckage was found the following morning about 60 km northwest of Ciudad Victoria Airport. The aircraft disintegrated on impact and all six occupants were killed.
Pilot:
Juan José Castro Maldonado
Passengers:
Maribel Lumbreras,
Paulina García Lumbreras,
Lucero Salazar Méndez,
Juana Lumbreras Ruiz,
Guadalupe Lumbreras Ruiz.

The pilot was engaged in an agricultural spraying mission. In unknown circumstances, the single engine aircraft impacted terrain and came to rest against a small hill in Mount Linton. The aircraft was damaged beyond repair and the pilot, sole aboard, was seriously injured.

The private pilot was conducting a personal cross-country flight. The pilot reported that, during cruise flight at 6,000 ft mean sea level, he observed a crew alerting system oil pressure message, followed by a total loss of engine power. An air traffic controller provided vectors to a local airport; however, the pilot reported that the airplane would not reach the runway. He did not attempt to restart the engine. He feathered the propeller and placed the power lever to "idle" and the condition lever to "cut off." The pilot subsequently attempted a forced landing to a sports field with the gear and flaps retracted. The airplane collided with trees and the ground and then came to rest upright. Examination of the engine revealed that it displayed contact signatures to its internal components and evidence of ingested unburned organic debris, consistent with the engine likely being unpowered and the engine gas generator and power sections wind-milling at the time of impact. No evidence of any preimpact mechanical anomalies or malfunctions to any of the engine components was found that would have precluded normal operation. Recorded GPS flight track and systems data showed that the loss of engine power was preceded by about 5 minutes of flight on a constant heading and altitude with an excessive lateral g force of about 0.17 g and a bank angle between about 8 and 10 degrees, consistent with a side-slip flight condition. The airplane then entered a right turn with the autopilot engaged, and it lost power at the end of the turn. The data indicated that, even though the autopilot was engaged, the lateral g forces increased as the airplane leveled off and accelerated, indicating that the automatic rudder trim feature of the yaw damper system was not engaged. Given that the yaw damper system operated normally after the flight, it is likely that the pilot inadvertently and unknowingly disengaged the yaw damper during flight with the autopilot engaged. During a postaccident interview, the pilot stated that he was not aware of a side-slip condition before the loss of engine power. Although the fuel tank system was designed to prevent unporting of the fuel lines during momentary periods of uncoordinated flight, it was not intended to do so for extended periods of uncoordinated flight. Therefore, the fuel tank feed line likely unported during the prolonged uncoordinated flight, which resulted in the subsequent loss of engine power. If the pilot had recognized the side-slip condition, he could have returned to coordinated flight and prevented the engine power loss. Also, once the airplane returned to coordinated flight, an engine restart would have been possible.

En route from Anaco to Santa Bárbara del Zulia, the twin engine aircraft crashed in unknown circumstances by a wooded area located near Casigua El Cubo. The aircraft was destroyed by a post crash fire and all three occupants were killed. It is believed that the aircraft was engaged in an illegal contraband flight.

The commercial pilot and his wife departed New York in their turboprop airplane on a crosscountry flight to Florida. About 1 hour 40 minutes into the flight and while cruising at flight level (FL) 280, the pilot notified air traffic control (ATC) of an abnormal indication in the airplane and requested a descent to FL180. The responding controller instructed the pilot to descend to FL250 and turn left 30°, and the pilot acknowledged and complied with the instruction; he then again requested a lower altitude. Although the pilot declined emergency handling and did not specify the nature of the problem, the controller independently determined that the flight had encountered a pressurization issue and immediately coordinated with another ATC facility to clear nearby traffic. The controller then issued instructions to the pilot to descend to FL200 and change course; however, the pilot did not comply with the assignments despite acknowledging the instructions multiple times. The pilot's failure to comply with the controller's instructions, his long microphone pauses after concluding a statement over the radio, and his confusion were consistent with cognitive impairment due to hypoxia. Further, the pilot's transmissions to ATC indicated impairment within 2 minutes 30 seconds of reporting the abnormal indication, which is consistent with the Federal Aviation Administration's published time of useful consciousness/effective performance time ranges for the onset of hypoxia. Military airplanes were dispatched about 30 minutes after the pilot's final transmission to ATC to intercept and examine the airplane. The pilots of the military airplanes reported that the airplane appeared to be flying normally at FL250, that both occupants appeared to be asleep or unconscious, and that neither occupant was wearing an oxygen mask. Photographs taken from one of the military airplanes revealed that the airplane's emergency exit door was recessed into the fuselage frame, consistent with a depressurized cabin. The military airplanes escorted the airplane as it continued on a constant course and altitude until it approached Cuban airspace, at which point they discontinued their escort. Radar data indicated that the airplane continued on the same flight track until about 5 hours 48 minutes after takeoff, when it descended to impact in the Caribbean Sea north of Jamaica. The flight's duration was consistent with a departure with full fuel and normal cruise endurance. Some of the wreckage, including fuselage and engine components, was recovered from the ocean floor about 4 months after the accident. Data recovered from nonvolatile memory in the airplane's global air system controller (GASC) indicated that several fault codes associated with the cabin pressurization system were registered during the flight. These faults indicated that the overheat thermal switch (OTSW), which was associated with overheat protection, had activated, which resulted in a shutdown of the engine bleed air supply to the cabin pressurization system. Without a bleed air supply to maintain selected cabin pressure, the cabin altitude would have increased to the altitude of the outside environment over a period of about 4 minutes. The faults recorded by the GASC's nonvolatile memory and associated system alerts/warnings would have been displayed to the pilot, both as discrete system anomaly messages on the crew alerting system (CAS) and as master warning and/or master caution annunciations. A witness report indicated that the pilot was known to routinely monitor cabin altitude while flying in the airplane and in his previous pressurized airplanes. Based on his instrument scanning practices and the airplane's aural warning system, he likely would have observed any CAS message at or near its onset. Thus, the CAS messages and the associated alerts were likely the precipitating event for the pilot's call to ATC requesting a lower altitude. The pilot was likely not familiar with the physiological effects of hypoxia because he had not recently been in an altitude chamber for training, but he should have been familiar with the airplane's pressurization system emergency and oxygen mask donning procedures because he had recently attended a transition course for the accident airplane make and model that covered these procedures. However, the pressurization system training segment of the 5-day transition course comprised only about 90 minutes of about 36 total hours of training, and it is unknown if the pilot would have retained enough information to recognize the significance of the CAS messages as they appeared during the accident flight, much less recall the corresponding emergency procedures from memory. Coupled with the pilot's reported diligence in using checklists, this suggests that he would have attempted a physical review of the emergency procedures outlined in the Pilot's Operating Handbook (POH). A review of the 656-page POH for the airplane found that only one of the four emergency checklist procedures that corresponded to pressurization system-related CAS messages included a step to don an oxygen mask, and it was only a suggestion, not a mandatory step. The combined lack of emergency guidance to immediately don an oxygen mask and the rapid increase in the cabin altitude significantly increased the risk of hypoxia, a condition resistant to self-diagnosis, especially for a person who has not recently experienced its effects in a controlled environment such as an altitude chamber. Additionally, once the pilot reported the problem indication to ATC, he requested a descent to FL180 instead of 10,000 ft as prescribed by the POH. In a second transmission, he accepted FL250 and declined priority handling. These two separate errors were either early signs of cognitive dysfunction due to hypoxia or indications that the pilot did not interpret the CAS messages as a matter related to the pressurization system. Although the cabin bleed-down rate was 4 minutes, the pilot showed evidence of deteriorating cognitive abilities about 2 minutes 30 seconds after he initially reported the problem to ATC. Ultimately, the pilot had less than 4 minutes to detect the pressurization system failure CAS messages, report the problem to ATC, locate the proper procedures in a voluminous POH, and complete each procedure, all while suffering from an insidious and mentally impairing condition that decreased his cognitive performance over time. Following the accident, the airplane manufacturer revised the emergency procedures for newly manufactured airplanes to require flight crews to don their oxygen masks as the first checklist item in each of the relevant emergency checklists. Further, the manufacturer has stated that it plans to issue the same revisions for previous models in 2017. The airplane manufacturer previously documented numerous OTSW replacements that occurred between 2008 and after the date of the accident. Many of these units were removed after the GASC systems in their respective airplanes generated fault codes that showed an overheat of the bleed air system. Each of the OTSWs that were tested at the manufacturer's facility showed results that were consistent with normal operating units. Additionally, the OTSW from the accident airplane passed several of the manufacturer's functional tests despite the presence of internal corrosion from sea water. Further investigation determined that the pressurization system design forced the GASC to unnecessarily discontinue the flow of bleed air into the cabin if the bleed air temperature exceeded an initial threshold and did not subsequently fall below a secondary threshold within 30 seconds. According to the airplane manufacturer, the purpose of this design was to protect the structural integrity of the airplane, the system, and the passengers in case of overheat detection. As a result of this accident and the ensuing investigation, the manufacturer made changes to the programming of the GASC and to the airplane's wiring that are designed to reduce the potential for the GASC to shut off the flow of bleed air into the cabin and to maximize the bleed availability. Contrary to its normal position for flight, the cockpit oxygen switch was found in the "off" position, which prevents oxygen from flowing to the oxygen masks. A witness's description of the pilot's before starting engine procedure during a previous flight showed that he may not have precisely complied with the published procedure for turning on the oxygen switch and testing the oxygen masks. However, as the pilot reportedly was diligent in completing preflight inspections and checklists, the investigation could not determine why the cockpit oxygen switch was turned off. Further, because the oxygen masks were not observed on either occupant, the position of the oxygen switch would not have made a difference in this accident.

The aircraft departed Mwanza Airport at 1926LT on a cargo flight Nairobi. While passing FL169, the aircraft entered an uncontrolled descent. It passed FL146 at an excessive speed of 430 knots and eventually crashed in an open field located near Kogatende. The wreckage was found the following morning. The aircraft disintegrated on impact and all three occupants were killed.

The twin engine aircraft departed Bukavu-Kavumu Airport at 1342LT on a cargo flight to Kama, carrying two pilots, two passengers and a load of 1,500 kilos of books. Some 10 minutes later, the crew changed his frequency and no further contact was established. As the aircraft failed to arrive in Kama, Maniema Province, SAR operations were initiated. The crew of two helicopters from the same operator spotted the burnt wreckage two days later, in the region of Mulume Munene, some 30 km southwest of Bukavu. The aircraft was destroyed by impact forces and a post crash fire and all four occupants were killed.

The single engine aircraft departed Cannes-Mandelieu Airport at 1040LT bound for Courtrai-Wevelgem Airport, Belgium, with four passengers and one pilot on board. About one hour and 40 minutes into the flight, while cruising in IMC conditions at FL240, the aircraft start a quick descent to the right until FL149. Speed increased and the overspeed warning sound came on. Forty-five seconds after the start of the quick descent, the airplane initiated a climb with a rate of 10,000 feet per minute until it stalled at FL201, still in IMC conditions. The airplane then entered a dive and went into a flat attitude when it went out of clouds at an altitude estimated between 1,000 and 2,000 feet. This altitude was insufficient to the pilot to regain control and without external visual references, he lost control of the airplane that crashed in a wooded area. The pilot and a passenger were killed while three other passengers were injured. The aircraft was destroyed.

The Swiftair MD-83 was performing flight AH5017 on behalf of Air Algérie (this regular schedule is performed four times a week). The aircraft left Ouagadougou at 0117Z and was attempting to land in Algiers at 0510LT but failed to arrive. 116 people (110 passengers and a crew of 6) were on board. The last position of the MD-83 was west of Gao, Mali. In the evening of July 24 (some 16 hours after the aircraft disappearance), the wreckage was eventually located and spotted some 50 km west of the city of Gossi, south Mali. The aircraft disintegrated on impact and no survivors was found among the 116 occupants. At the time of the accident, bad weather conditions with storm activity, winds, turbulence and icing was confirmed over the region of Gao, until an altitude of 40,000 feet. At the time of the accident, the aircraft was flying west of this marginal weather area and referring to the French BEA graphic, the aircraft did not properly get around this turbulent area. It was confirmed the aircraft started a left turn from the altitude of 31,000 feet and then spiraled to the ground in less than three minutes (140° bank left and 80° nose down until impact). The last position recorded by the FDR at 0147LT and 15 seconds was at the altitude of 1,600 feet (490 meters) and at a speed of 380 KIAS (740 km/h) with a very high rate of descent.

Flight MH17 departed the gate at Amsterdam-Schiphol Airport, the Netherlands at 12:13 hours local time, bound for Kuala Lumpur, Malaysia. It was airborne at 12:31 (10:31 UTC) from runway 36C and reached a cruising altitude of FL310 at 12:53 (10:53 UTC). Ninety minutes into the flight, at 12:01 UTC and just prior to entering Ukrainian airspace, the flight climbed to FL330. According to the flight plan, flight MH17 would continue at the flight level until the waypoint PEKIT, which is on the Flight Information Region (FIR) boundary between Kiev FIR (UKBV) and Dnipropetrovs’k FIR (UKDV). From waypoint PEKIT the flight plan indicates a climb to FL350 on airway L980 for the remaining part over Ukraine. According to ATC data, at 12:53 UTC the aircraft was flying within the Dnipropetrovs’k FIR, Control Sector 2, at FL330, controlled by Dnipro Control. At that time, Dnipro Control asked whether MH17 was able to climb to FL350 in accordance with the flight plan and also to clear a potential separation conflict with other traffic in the area. This traffic was Singapore Airlines flight SQ351 from Copenhagen, a Boeing 777, flying at FL330 and approaching from behind. The crew replied they were unable to comply and requested to maintain at FL330. This was agreed by Dnipro Control. As an alternative to solve the separation conflict, the other traffic climbed to FL350. According to ATC data, at 13:00 UTC the crew of flight MH17 requested to divert the track 20 NM to the left, due to weather. This also was agreed by Dnipro Control, after which the crew requested whether FL340 was available. Dnipro control informed MH17 that FL340 was not available at that moment and instructed the flight to maintain FL330 for a while. At 13:07 UTC the flight was transferred to Dnipropetrovs’k CTA 4, also with call sign Dnipro Control. At 13:19:53 UTC, radar data showed that the aircraft was 3.6 NM north of centreline of airway L980 having deviated left of track, when Dnipro Control directed the crew to alter their route directly to waypoint RND due to other traffic. The crew acknowledged at 13:19:56 hrs. At 13.20:00 hrs, Dnipro Control transmitted an onward ATC clearance to "proceed direct to TIKNA after RND", no acknowledgement was received. Data from the Flight Data Recorder and the Digital Cockpit Voice Recorder both stopped at 13:20:03 hrs. No distress messages were received from the aircraft. The airplane apparently broke up in mid-air as debris was found in a large area. The centre section of the fuselage along with parts of the horizontal and vertical stabilizers was found near Hrabove. The cockpit and lower nose section came down in a sunflower field in Rozsypne, nearly four miles (6,5 km) west-southwest of Hrabove. The L2 and R2 doors along with various parts of the fuselage were found near Petropavlivka, about 5 miles (8 km) west of Hrabove. At the point of last contact it was flying 1000 feet above airspace that had been classified as restricted by Ukrainian authorities as a result of ongoing fighting in the area. In the preceding days before the accident two Ukraine Air Force aircraft that were shot down in the region: a Su-25 and an An-26 transport plane.