Private

The commercial pilot and three passengers were making a personal cross-country flight over ocean waters in the MU-2B airplane. During cruise flight at flight level (FL) 240, the airplane maintained the same relative heading, airspeed, and altitude for about 2.5 hours before radar contact was lost. While the airplane was in flight, a significant meteorological information notice was issued that warned of frequent thunderstorms with tops to FL440 in the accident area at the accident time. Satellite imagery showed cloud tops in the area were up to FL400. Moderate or greater icing conditions and super cooled large drops (SLD) were likely near or over the accident area at the accident time. Although the wreckage was not located for examination, the loss of the airplane's radar target followed by the identification of debris and a fuel sheen on the water below the last radar target location suggests that the airplane entered an uncontrolled descent after encountering adverse weather and impacted the water. Before beginning training in the airplane about 4 months before the accident, the pilot had 21 hours of multi engine experience accumulated during sporadic flights over 9 years. Per a special federal aviation regulation, a pilot must complete specific ground and flight training and log a minimum of 100 flight hours as pilot-in-command (PIC) in multi engine airplanes before acting as PIC of a MU-2B airplane. Once the pilot began training in the airplane, he appeared to attempt to reach the 100-hour threshold quickly, flying about 50 hours in 1 month. These 50 hours included about 40 hours of long, cross-country flights that the flight instructor who was flying with the pilot described as "familiarization flights" for the pilot and "demonstration flights" for the airplane's owner. The pilot successfully completed the training required for the MU-2B, and at the time of the accident, he had accumulated an estimated 120 hours of multi engine flight experience of which 100 hours were in the MU-2B. Although an MU-2B instructor described the pilot as a good, attentive student, it cannot be determined if his training was ingrained enough for him to effectively apply it in an operational environment without an instructor present. Although available evidence about the pilot's activities suggested he may not have obtained adequate restorative sleep during the night before the accident, there was insufficient evidence to determine the extent to which fatigue played a role in his decision making or the sequence of events.The pilot's last known weather briefing occurred about 8 hours before the airplane departed, and it is not known if the pilot obtained any updated weather information before or during the flight. Sufficient weather information (including a hazardous weather advisory provided by an air traffic control broadcast message about 25 minutes before the accident) was available for the pilot to expect convective activity and the potential for icing along the accident flight's route; however, there is no evidence from the airplane's radar track or the pilot's communications with air traffic controllers that he recognized or attempted to avoid the convective conditions or exit icing conditions.

On April 17th, at 11:04 UTC, the aircraft turboprop Piper PA-31 Cheyenne II, registration HBLTI, private property, took off from runway 17 of the Cascais aerodrome (LPCS) bound to Marseille airport (LFML), IFR private flight, with 1 pilot and 3 passengers on board. According to several eyewitness testimonies, after takeoff, the Swiss twin-engine started to put the left wing down and consequently to turn left while climbing slowly to about 300’ feet of altitude. The left bank1 increased and the speed decreased leading the aircraft to stall. The aircraft entered a steep dive and impacted the ground next to a logistics dock of a local supermarket, located southeast of the airfield. The crash occurred 700 m from the end of the departure runway. Following the impact, the aircraft exploded and caught fire affecting a logistic dock, a house and a truck. The aircraft was destroyed by impact force and the post-collision fire, all the four occupants were killed. The driver of the truck affected by the explosion of the plane was also killed. The fuselage, wings, the engines and propellers were severely damaged by the impact force and post-impact fuel-fed fire. The structural damage to the aircraft was consistent with the application of extensive structural loads during the impact sequence, and the effects of the subsequent fire. No pre-crash structural defects were found. All aircraft parts and control surfaces were located at the site. The flaps and the landing gear were found retracted at the time of impact.

The commercial pilot and three passengers departed on an instrument flight rules crosscountry flight. While on approach to the destination airport, the pilot indicated to the air traffic controller that the airplane was passing through areas of moderate-to-extreme precipitation. After clearing the airplane for the approach, the controller noted that the airplane descended below its assigned altitude; the controller issued a low altitude alert, but no response was received from the pilot. The airplane subsequently impacted terrain in a level attitude about 12 miles from the airport. Examination of the airframe, engine, and system components revealed no evidence of preimpact mechanical malfunction that would have precluded normal operation. An area of disturbed, flattened, tall grass was located about 450 ft southwest of the accident site. Based on the images of the grass, the National Weather Service estimated that it would take greater than 35 knots of wind to lay over tall grass as the images indicated, and that a downburst/microburst event could not be ruled out. A downburst is an intense downdraft that creates strong, often damaging winds. About 6 hours before the flight, the pilot obtained weather information through a mobile application. Review of weather data indicated the presence of strong winds, heavy precipitation, turbulence, and low-level wind shear (LLWS) in the area at the time of arrival, which was reflected in the information the pilot received. Given the weather conditions, it is likely that the airplane encountered an intense downdraft, or downburst, which would have resulted in a sudden, major change in wind velocity. The airplane was on approach for landing at the time and was particularly susceptible to this hazardous condition given its lower altitude and slower airspeed. The downburst likely exceeded the climb performance capabilities of the airplane and resulted in a subsequent descent into terrain. It is unknown if the accident pilot checked or received additional weather information before or during the accident flight. While the flight was en route, several PIREPs were issued for the area of the accident site, which also indicated the potential of LLWS near the destination airport; however, the controller did not provide this information to the pilot, nor did he solicit PIREP information from the pilot. Based on published Federal Aviation Administration guidance for controllers and the widespread adverse weather conditions in the vicinity of the accident site, the controller should have both solicited PIREP information from the pilot and disseminated information from previous PIREPs to him; this would have provided the pilot with more complete information about the conditions to expect during the approach and landing at the destination.

The private pilot departed on an instrument flight rules flight plan in his twin-engine turbojet airplane. The flight was uneventful until the air traffic controller amended the flight plan, which required the pilot to manually enter the new routing information into the GPS. A few minutes later, the pilot told the controller that he was having problems with the GPS and asked for a direct route to his destination. The controller authorized the direct route and instructed the pilot to descend from 22,000 ft to 6,000 ft, during which time the sound of the autopilot disconnect was heard on the cockpit voice recorder (CVR). During the descent, the pilot told the controller that the airplane had a steering problem and was in the clouds. The pilot was instructed to descend the airplane to 4,100 ft, which was the minimum vectoring altitude. The airplane continued to descend, entered visual meteorological conditions, and then descended below the assigned altitude. The controller queried the pilot about the airplane's low altitude and instructed the pilot to maintain 4,100 ft. The pilot responded that he was unsure if he would be able to climb the airplane back to that altitude due to steering issues. The controller issued a low altitude warning and again advised the pilot to climb back to 4,100 ft. The pilot responded that the autopilot was working again and that he was able to climb the airplane to the assigned altitude. The controller then instructed the pilot to change to another radio frequency, but the pilot responded that he was still having a problem with the GPS. The pilot asked the controller to give him direct routing to the airport. A few minutes later, the pilot told the controller that he was barely able to keep the airplane straight and its wings level. The controller asked the pilot if he had the airport in sight, which he did not. The pilot then declared an emergency and expressed concerns related to identifying the landing runway. Afterward, radio contact between the controller and the pilot was lost. Shortly before the airplane impacted the ground, a witness saw the airplane make a complete 360° roll to the left, enter a steep 90° bank to the left, roll inverted, and enter a vertical nose-down dive. Another witness saw the airplane spiral to the ground. The airplane impacted the front lawn of a private residence, and a postcrash fire ensued.The pilot held a type rating for the airplane, but the pilot's personal logbooks were not available for review. As a result, his overall currency and total flight experience in the accident airplane could not be determined. The airplane was originally certified for operations with a pilot and copilot. To obtain an exemption to operate the airplane as a single pilot, a pilot must successfully complete an approved single-pilot exemption training course annually. The accident airplane was modified, and the previous owner was issued a single-pilot conformity certificate by the company that performed the modifications. However, there was no record indicating that the accident pilot received training under this exemption. Several facilities that have single-pilot exemption training for the accident airplane series also had no record of the pilot receiving training for single-pilot operations in the accident airplane. Therefore, unlikely that the pilot was properly certificated to act as a single-pilot. The GPS was installed in the airplane about 3.5 years before the accident. A friend of the pilot trained him on how to use the GPS. The friend said that the pilot generally was confused about how the unit operated and struggled with pulling up pages and correlating data. The friend of the pilot had flown with him several times and indicated that, if an air traffic controller amended a preprogrammed flight plan while en route, the pilot would be confused with the procedure for amending the flight plan. The friend also said the pilot depended heavily on the autopilot, which was integrated with the GPS, and that he would activate the autopilot immediately after takeoff and deactivate it on short final approach to a runway. The pilot would not trim the airplane before turning on the autopilot because he assumed that the autopilot would automatically trim the airplane, which led to the autopilot working against the mis-trimmed airplane. The friend added that the pilot was "constantly complaining" that the airplane was "uncontrollable." A postaccident examination of the airplane and the autopilot system revealed no evidence of any preimpact deficiencies that would have precluded normal operation. This information suggests that pilot historically had difficulty flying the airplane without the aid of the autopilot. When coupled with his performance flying the airplane during the accident flight without the aid of the autopilot, it further suggests that the pilot was consistently unable to manually fly the airplane. Additionally, given the pilot's previous experience with the GPS installed on the airplane, it is likely that during the accident flight the pilot became confused about how to operate the GPS and ultimately was unable to properly control of the airplane without the autopilot engaged. Based on witness information, it is likely that during the final moments of the flight the pilot lost control of the airplane and it entered an aerodynamic stall. The pilot was then unable to regain control of the airplane as it spun 4,000 ft to the ground.

Pilot advised that upon making his approach to land at Cat Cay (MYCC), on short final he experienced an unexpected accelerated sink rate. To compensate for the sink rate he increased the pitch of the aircraft. While going over the threshold, a slight impact was felt as the landing gear came into contact with the seawall. He flew the aircraft until it came to a stop about 600 feet down the runway. No injuries were sustained, aircraft received substantial damage.

The 69-year-old commercial pilot was making a personal cross-country flight in the newly purchased airplane. When the airplane was on final approach to the destination airport in night visual meteorological conditions, airport surveillance video showed it pitch up and roll to the right. The airplane then descended in a nose-down attitude to impact in a ravine on the right side of the runway. During the descent over the ravine the right wing came in contact with a powerline that briefly cut power to the airport. Postaccident examination of the airframe, engines, and their components revealed no evidence of mechanical anomalies or malfunctions that would have precluded normal operation. The pilot's toxicology findings identified five different impairing medications: clonazepam, temazepam, hydrocodone, nortriptyline, and diphenhydramine. Although the results were from cavity blood and may not accurately reflect antemortem levels, the hydrocodone, temazepam, and diphenhydramine levels were high enough to likely have had some psychoactive effects. While the exact effects of these drugs in combination are not known, it is likely that the pilot was impaired to some degree by his use of this combination of medications, which likely contributed to his failure to maintain control of the airplane.

The pilot of the twin-engine airplane and the pilot-rated passenger reported that, during a missed approach in instrument meteorological conditions, at 2,000 ft mean sea level, the right engine seized. The pilot attempted to feather the right engine by pulling the propeller control to the feather position; however, the engine did not feather. The airplane would not maintain level flight, so the pilot navigated to a known airport, and the passenger made emergency communications with air traffic control. The pilot was unable to maintain visual reference with the ground until the airplane descended through about 100 to 200 ft and the visibility was 1 statute mile. The pilot stated that he was forced to ditch the airplane in the water about 5 miles short of the airport. The pilot and passenger egressed the airplane and swam ashore before it sank in about 89 ft of water. Both the pilot and passenger reported that there was postimpact fire on the surface of the water. The airplane was not recovered, which precluded a postaccident examination. Thus, the reason for the loss of engine power could not be determined.

The pilot reported that, during the preflight, it was snowing, and he wiped the snow that had accumulated on the wings off "as best as [he] could." He added that, while taxiing to the runway, "snow was falling heavily," and he observed "light accumulation of wet snow" on the wings. During the takeoff roll, he observed the snow "sloughing off" the wings as the airspeed increased. Subsequently, during the climb to about 150 ft above the ground, the airplane yawed to the left, and he attempted to recover using right aileron. He reported that he "could see a stall forming," so he lowered the nose and reduced power to idle. The airplane impacted the general aviation ramp in a left-wing-down attitude and slid 500 to 600 ft. The pilot reported on the National Transportation Safety Board Aircraft Accident/ Incident Report 6120.1 form that the airplane stalled, and he recommended "better deicing" before takeoff. The airplane sustained substantial damage to the fuselage and left wing. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation. A review of recorded data from the automated weather observation station located on the airport revealed that, about 27 minutes before the accident, the wind was 010° at 8 knots, 1/2-mile visibility, moderate snow, freezing fog, and sky condition broken at 500 ft above ground level (agl) and overcast at 1,500 ft agl. The airplane departed from runway 16. The Federal Aviation Administration (FAA) Aeronautical Information Manual stated, in part: "The presence of aircraft airframe icing during takeoff, typically caused by improper or no deicing of the aircraft being accomplished prior to flight has contributed to many recent accidents in turbine aircraft." The manual further stated, "Ensure that your aircraft's lift-generating surfaces are COMPLETELY free of contamination before flight through a tactile (hands on) check of the critical surfaces when feasible. Even when otherwise permitted, operators should avoid smooth or polished frost on lift-generating surfaces as an acceptable preflight condition." FAA Advisory Circular, AC 135-17, stated in part: "Test data indicate that ice, snow, or frost formations having thickness and surface roughness similar to medium or course sandpaper on the leading edge and upper surfaces of a wing can reduce wing lift by as much as 30 percent and increase drag by 40 percent." Included in the public docket for this report is a copy of a service bulletin from the airplane manufacturer, which describes deicing and anti-icing ground procedures. It stated, in part: During conditions conducive to aeroplane icing during ground operations, take-off shall not be attempted when ice, snow, slush or frost is present or adhering to the wings, propellers, control surfaces, engine inlets or other critical surfaces. This is known as the "Clean Aircraft Concept". Any deposit of ice, snow or frost on the external surfaces may drastically affect its performance due to reduced aerodynamic lift and increased drag resulting from the disturbed airflow.

While overflying the Yucatán Province, en route from Monterrey to Cancún, the pilot informed ATC that he was low of fuel and requested the permission to divert to Chichén Itzá Airport for an emergency landing. While approaching the airfield by night, the single engine aircraft descended into trees and crashed few km from the airport. The airplane was destroyed and there was no fire. All five occupants were injured.

The pilot and the passenger departed on a cross-country, personal flight in the airplane that the operator had purchased the day before the accident. Shortly after takeoff from runway 11L, after reaching an altitude of about 100 to 150 ft above the runway in a nose-high pitch attitude, the airplane rolled left to an inverted position as its nose dropped, and it descended to terrain impact on airport property, consistent with an aerodynamic stall. Post-accident examination of the accident site revealed propeller strike marks separated at distances consistent with both propellers rotating at the speed required for takeoff and in a normal blade angle range of operation at impact. Both engines exhibited rotational scoring signatures that indicated the engines were producing symmetrical power and were most likely operating in the mid-to upper-power range at impact. The engines did not display any pre-impact anomalies or distress that would have precluded normal engine operation before impact. No evidence was found of any preexisting mechanical anomalies that would have precluded normal operation of the airplane. Toxicology testing revealed the pilot's use of multiple psychoactive substances including marijuana, venlafaxine, amphetamine, pseudoephedrine, clonazepam, and pheniramine. The wide variety of psychoactive effects of these medications precludes predicting the specific effects of their use in combination. However, it is likely that the pilot was impaired by the effects of the combination of psychoactive substances he was using and that those effects contributed to his loss of control. The investigation was unable to obtain medical records regarding any underlying neuropsychiatric disease(s); therefore, whether these may have contributed to the accident circumstances could not be determined.