Mountains

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.

During an aerial fire suppression mission for the California Department of Forestry (CDF), two Grumman TS-2A airplanes, operating as Tanker 92 (N442DF) and Tanker 87 (N450DF), collided in flight while in a holding pattern awaiting a retardant drop assignment on the fire. All of the airplanes fighting the fire were TS-2A's, painted in identical paint schemes. The Air Tactical Group Supervisor (AirTac) was orbiting clockwise 1,000 feet above the tankers, who were in a counterclockwise orbit at 3,000 feet mean sea level (msl). The pilots of both aircraft involved in the collision had previously made several drops on the fire. Records from the Air Tac show that Tankers 86, 91, and 92 were in orbit, and investigation found that Tanker 87 was inbound to enter the orbit after reloading at a nearby airport base. AirTac would write down the tanker numbers as they made their 3-minutes-out call, and usually ordered their drops in the same order as their check-in. The AirTac's log recorded the sequence 86, 91, 21, and 92. The log did not contain an entry for Tanker 87. Other pilots on frequency did not recall hearing Tanker 87 check in. Based on clock codes with 12-o'clock being north, the tankers were in the following approximate positions of the orbit when the collision occurred. Tanker 92 was at the 2-o'clock position; Tanker 86 was turning in at the 5-o'clock position; and Tanker 91 was in the 7-o'clock position. The AirTac's log indicated that Tanker 92 was going to move up in sequence and follow Tanker 86 in order to drop immediately after him. Post accident examination determined that Tanker 92's flaps were down, indicating that the pilot had configured the airplane for a drop. Tanker 92 swung out of the orbit wide (in an area where ground witnesses had not seen tankers all day) to move behind Tanker 86, and the pilot would likely have been focusing on Tanker 86 out of his left side window. Tanker 87 was on line direct to the center of the fire on a path that witnesses had not observed tankers use that day. Reconstruction of the positions of the airplanes disclosed that Tankers 86 and 91 would have been directly in front of Tanker 87, and Tanker 92 would have been wide to his left. Ground witnesses said that Tanker 87 had cleared a ridgeline just prior to the collision, and this ridgeline could have masked both collision aircraft from the visual perspective of the respective pilots. The right propeller, engine, and cockpit of Tanker 92 contacted and separated the empennage of Tanker 87. The propeller chop was about 47 degrees counterclockwise to the longitudinal axis of Tanker 87 as viewed from the top. The collision appeared to have occurred about 2,500 feet, which was below orbit altitude. CDF had no standard operating manual, no established reporting or entry point for the holding orbits, and a tanker could enter any point of the orbit from any direction. While no standardized procedures were encoded in an operating manual, a CDF training syllabus noted that a tanker was not to enter an orbit until establishing positive radio contact with the AirTac. The entering tanker would approach 1,000 feet below AirTac's altitude and stay in a left orbit that was similar to a salad bowl, high and wide enough to see and clear all other tankers until locating the tanker that it was to follow, then adjust speed and altitude to fall in behind the preceding airplane.