Mountains

The pilot was on a visual rules flight from Culebra, Puerto Rico to San Juan, Puerto Rico. No flight plan was filed and a weather briefing was not obtained. The pilot contacted San Juan Radar Approach Control 10 miles east of Fajardo, Puerto Rico and the controller stated the airplane was in radar contact 3 miles east of Fajardo airport. The pilot was instructed to enter a right downwind for runway 10 south of plaza Carolina. The pilot acknowledged the transmission and reported he was at 1,600 feet. Two minutes later the controller stated on the radio frequency, radar contact was lost. The airplane was located by ground personnel on the side of El Yunque Mountain. Review of weather data revealed a weak cold front extended over Puerto Rico. Satellite imagery at the time of the accident revealed a band of low clouds obscuring the accident site. A police helicopter pilot who attempted to reach the crash site reported instrument flight conditions. Examination of the airframe, flight controls, engine assemblies and accessories revealed no anomalies.

On the morning of Sunday 23 December 2001, the pilot was engaged in spreading superphosphate on a property near Otonga. When this job was completed the operation moved to a property to the east of Whangarei where urea was sown on a maize crop. This job finished at about 1130 hours when the pilot and loader driver decided to have a cup of tea and determine which job they would do next. There were two options available; it was found that the wind was unsuitable for operations from one airstrip, so it was decided to complete the job at Paiaka, which involved spreading some 112 tonnes of lime. This particular job was to have commenced on 13 December 2001 but was delayed because of wind. The loader driver arrived at Paiaka at about 1300 hours to find that the pilot had already landed and was removing the cover from the fertiliser bin that held the lime. The loader driver noticed that water had come under the edges of the cover making the lime damp around the walls of the bin. The truck driver who had delivered lime earlier in the week had also noted the presence of moisture in the lime around the edges of the bin. The work commenced at about 1320 hours and the loader driver expected the pilot to stop for fuel between 1445 and 1500 hours. After approximately 13 loads the loader driver was using the lime that had been affected by moisture. As a result he took bucket loads from the sides of the bin and mixed it with the lime in the middle of the bin in an effort to make the lime flow more freely. At approximately 1425 the pilot gave the signal to the loader driver for a refuel on the next landing. As this was earlier than the expected refuel time the loader driver assumed this was also to check if any lime was building up around the bottom of the hopper. During the 10 weeks that they had been operating the aircraft they had to clean fertiliser away from the hopper door area. This had happened several times, especially if the fertiliser was damp, and on one occasion they had to clean out part of a previous fertiliser load that had “hung up” inside the hopper. As the loader driver was preparing for the refuel he could hear the aeroplane operating under what sounded like full power, and saw the pilot manoeuvre the aircraft in an apparent attempt to dislodge the load. He saw a small “puff” of lime discharge from the aircraft as it was “bunted”. The aircraft then disappeared behind intervening terrain into a valley, some 1,500 metres from the sowing area. The loader driver did not see the aeroplane again, but heard a muffled explosion and saw smoke on the skyline. He then phoned for emergency assistance. The accident occurred in daylight, at approximately 1430 hours NZDT, at Paiaka, at an elevation of 720 feet. Grid reference 260-Q06-142267, latitude S 35° 33 2', longitude E 174° 08.3'.

After takeoff from Medellín-Enrique Olaya Herrera Airport runway 01, the crew initiated a turn to the right and continued to climb. In poor visibility due to clouds, at an altitude of 9,200 feet, the twin engine aircraft struck the slope of Mt El Silencio near San Antonio de Prado. The aircraft was destroyed by impact forces and a post crash fire and all 16 occupants were killed. At the time of the accident, weather was poor with towering cumulus and rain falls.

En route from Bunia to Beni, while cruising in poor weather conditions, the twin engine airplane crashed in a wooded and hilly terrain located near Geti, some 40 km east of Bunia. All six occupants were killed. The exact cause of the accident remains unknown but the aircraft may have been shot down by Allied Democratic Forces (ADF) rebels fighting the Uganda government.

The single engine airplane departed San José Airport on a schedule flight to Puerto Jiménez with an intermediate stop in Quepos, carrying six passengers (3 Americans, 2 Germans and one Dutch) and two pilots. While descending in clouds to Quepos Airport, the aircraft collided with trees and crashed on the slope of a wooded mountain located about 13 km from Quepos Airport. Both pilots and one passenger were killed while five other passengers were seriously injured. The aircraft was totally destroyed by impact forces.

The airplane collided with mountainous terrain during cruise after encountering turbulence and downdrafts associated with mountain wave conditions. According to Federal Aviation Administration (FAA) records, the pilot called the Reno Automated Flight Service Station at 0941 and filed an IFR flight plan, then asked for the winds aloft forecast, which was provided. The pilot did not request any additional weather briefing information for the flight. No other record was found that the pilot obtained additional weather forecast information from any official source associated with the FAA or the National Weather Service. At the time of the pilot's call to the Reno AFSS, several AIRMET weather advisories had been issued hours prior detailing warnings for turbulence and clear icing along the route of flight. The advisories warned of occasional moderate turbulence below 18,000 feet in moderately strong westerly winds especially in the vicinity of mountainous terrain. Clear Air Turbulence (CAT) between 18,000 and 40,000 feet was forecast over the area of the accident site due to jet stream wind shear and mountain wave activity. The pilot departed under visual flight rules (VFR) and picked up his instrument flight rules (IFR) clearance en route and climbed to 14,000 feet. The pilot later asked if he could maintain 12,500 feet. The controller advised him that the minimum IFR altitude on this segment of his route was 14,000 feet, and the pilot cancelled his IFR flight plan. The controller advised the pilot that he had lost radar contact, and instructed the pilot to squawk VFR and the pilot acknowledged the transmission. The last radar target was about 1/2 mile east of Eagle Peak (elevation 9,920 feet) in the Warner Mountains. Rescuers discovered the wreckage near the crest of Eagle Peak on November 23. Investigators found no anomalies with the airframe, engines, or propellers that would have precluded normal operation. The NWS had a full series of AIRMETs current over the proposed route of flight, which included mountain obscuration, turbulence, and icing. Analysis of the weather conditions disclosed a layer between 9,500 and 11,000 feet over the accident site area as having a high likelihood of severe or greater turbulence. A pilot on the same route of flight reported at 1127 that he was in instrument conditions at 11,000 feet, and experiencing light turbulence and light clear icing conditions. He also reported encountering updrafts of 2,000 feet per minute, which was indicative of mountain wave activity. A company pilot was in a second Aero Commander trailing the accident airplane and he reported that at 1147, at a position near the accident site, he encountered a severe downdraft. He applied full climb power, but as the airplane passed over the accident site position, the airplane continued to lose altitude even at maximum power. At 1159, he was able to gain altitude, and return to his assigned cruising altitude of 14,000 feet. The second Aero Commander was turbocharged, the accident airplane was not. Analysis showed that the topography of the area was critical in this case, given that the accident site was at an elevation of 9,240 feet on the eastern slope of Eagle Peak. The accident airplane's flight track was normal along the airway until immediately downwind of the higher terrain. As the flight approached the lee side of the mountain, it came under the influence of the mountain wave and first encountered an updraft and then a downdraft, which increased in amplitude as the flight progressed towards Eagle Peak. Eagle Peak was the tallest point along the Warner Mountain range and the steep slope of this terrain was significant when the mountain wave action was encountered. Such terrain features have been known to enhance the vertical downdrafts and updrafts associated with the most intense mountain wave turbulence.

At 2144, the pilot contacted air traffic control and requested visual flight rules (VFR) flight following to his destination. The flight was the final leg of a four-leg trip, which the pilot had begun approximately 1120 that morning. At 2220, the flight began a slow descent toward the destination airport. Radar data confirmed that the airplane executed a steady descent, and flew a straight line course toward Graham. The final radar return occurred 37 minutes later at an altitude of 3,000 feet (radar coverage is not available below 3,000 feet), 8 miles southeast of the Graham Municipal Airport. Two minutes after the final radar return, the pilot reported to air traffic control that the flight was two miles out, and he canceled VFR flight following. No further communications or distress calls were received from the airplane. The pilot did not request or receive updated weather from the air traffic controllers during the flight. According to witnesses who lived near the accident site, they heard an airplane flying low, observed dense fog and heard the sounds of an airplane crashing. According to the nearest weather reporting station, near the time of the accident, the temperature- dew point spread was within 2 degrees, visibilities were reduced to between 3 and 4 miles in fog, and the ceiling was decreasing from 600 feet broken to 400 feet overcast. At the time of the accident, the pilot's duty day exceeded 12 hours. Examination of the airframe revealed no preimpact anomalies and that the gear was extended and the flaps were retracted. Examination of both engines revealed evidence of power at the time of impact.

While descending to Campo dos Afonsos AFB, the crew encountered poor weather conditions with limited visibility due to fog and rain falls. Too low, the four engine aircraft struck the slope of a mountain located about 15 km southeast of the airbase. All nine occupants were killed.

The airplane was on a non-scheduled cargo flight which was projected to fly an approximate 240 degree course for 92 nm. The accident site was located on a heavily forested steep mountain side, 15 to 16 nm north of the airplane's projected course. The debris field began at an east-west ridge line, and progressed for 300 feet on a 010 degree track to the downed airplane. Examination of the airframe and engines revealed no evidence of preimpact discrepancies. The accident site was in an area where the Fall color of the aspens was at its peak. Additionally, it was an area where elk were sometimes observed.

The twin engine aircraft departed Mahajanga, Madagascar, on a charter flight to Saint-Denis de La Réunion, with an intermediate stop in Antananarivo, carrying five passengers and two pilots. While approaching Antananarivo-Ivato Airport, the aircraft went out of control and crashed in a mountainous area located about 30 km from the airport. The aircraft was destroyed and all seven occupants were killed.