De Havilland DHC-6 Twin Otter

On approach to Dembidolo by night and stratus clouds, the crew failed to realize his altitude was too low. While facing a mountain, the crew increased engine power to gain height but the aircraft stalled, lost altitude and crashed on a hilly terrain located few km from the airfield. All 20 occupants were injured while the aircraft was damaged beyond repair.

On June 18, 1986, at 0855 mountain standard time, a Grand Canyon Airlines DHC-6, N76GC (Twin Otter), call sign Canyon 6, took off from runway 21 of the Grand Canyon Airport. The flight, a scheduled air tour over Grand Canyon National Park, was to be about 50 minutes in duration. Shortly thereafter, at 0913, a Helitech Bell 2068 (Jet Ranger), NGTC, call sign Tech 2, began its approximate 30-minute, on-demand air tour of the Grand Canyon. It took off from its base at a heliport adjacent to State route 64 in Tusayan, Arizona, located about 5 miles south of the main entrance to the south rim of the National Park. Visual meteorological conditions prevailed. The two aircraft collided at an altitude of 6,500 feet msl in the area of the Tonto Plateau. There were 18 passengers and 2 flightcrew members on the DHC-6 and 4 passengers and 1 flightcrew member on the Bell 206B. All 25 passengers and crew members on both aircraft were killed as a result of the collision. Because of the lack of cockpit voice recorders and flight data recorders in both aircraft, as well as the lack of radar data, no assessment of the flight path of either aircraft could be made. As a result, the reason for the failure of the pilots of each aircraft to “see and avoid” each other cannot be determined. Consequently, the issues highlighted in this report concern primarily the oversight of the Federal Aviation Administration (FAA) on Grand Canyon-based scenic air tours or sightseeing flights and the actions of the National Park Service to influence these operations. Because of an exemption to 14 Code of Federal Regulations (CFR) Part 135, local scenic air tours were conducted under 14 CFR Part 91. This investigation revealed that there was no FAA oversight on the routes and altitudes of Grand Canyon-based scenic air tour operators. This was contrary to the intent of Safety Recommendation A-84-52. Further, the National Park Service, through its authority under a 1975 law, was conducting a study to determine the effects of aircraft noise on the Grand Canyon and, at the same time, influencing the selection of air tour routes. The routes of the rotary-wing operators were ‘moved as a noise conservation measure to where they converged with those of Grand Canyon Airlines at the location of the accident. Other safety issues concern the lack of regulations to limit flight and duty times of pilots conducting scenic air tour flights, and the lack of a requirement for the pilots of such flights to use intercoms or public address systems when narrating during the flights. All 20 occupants of the Twin Otter were killed, among them 11 citizen from The Netherlands and two Swiss.

The crew was engaged in a SAR mission after a small plane disappeared. While flying in relative good weather conditions, the aircraft struck the slope of a mountain located in the Kananaskis Park, about 75 km west of Calgary. The aircraft was destroyed and all eight occupants were killed, three crew members and five observers.
Crew:
Cpt Ted Katz, pilot
Cpt Wayne Plumbtree, copilot,
Brian Burkett, flight engineer.

Loganair Flight LC423 was a scheduled passenger flight from Glasgow Airport (GLA) to Islay/Port Ellen (ILY). The handling pilot, who occupied the first pilot's position, had recently converted to flying the DHC-6 Twin Otter aircraft, and was completing a series of supervised route flights required by the airline before the award of full command status. A company supervisory captain, the designated commander for this flight, occupied the co-pilot's position. The Twin Otter's engines were started at 14:38, and, at 14:44, Glasgow Airport ATC approved taxy clearance to the holding point of runway 28. The aircraft was operating on a stored Instrument Flight Rules (IFR) flight plan. The requested routeing was a Standard Instrument Departure (SID), to join Airway Blue 2 for the Skipness VOR beacon, and thereafter direct to the Islay/Port Ellen NDB. The direct track is the 272° Magnetic (M) radial from Skipness. At 14:46 Glasgow ATC advised LC423 of their flight clearance. The requirement to fly the SID was cancelled and the aircraft was cleared direct to Skipness, cruising level FL55. The aircraft took off from runway 28 at 14:48. The aircraft reported a position overhead the Skipness VOR at 15:08. At this point Scottish Airways Control informed LC423 that they should clear controlled airspace, contact Port Ellen, and that there was no known traffic to affect their descent. After passing overhead the Skipness VOR the aircraft did not depart that position on the 272° radial, but instead turned 15° left, and descended on the 257° radial towards the south of the island of Islay. At 15:10, having already started to descend, LC423 contacted Islay/Port Ellen, reported an arrival time of 15:23, and requested details of the latest weather. The Islay/Port Ellen radio operator replied that the weather details were a surface wind of 220°/05 knots, visibility 2000 metres in drizzle, cloud 3 oktas at 400 feet, 5 oktas at 700 feet, and 8 oktas at 1400 feet. The sea level barometric pressure was 1018 millibars. LC423 acknowledged the information and was asked to advise when overhead the aerodrome at 3600 feet, or when in visual contact. The aircraft then continued to descend, on a track of about 260° M towards the south of the island, until it disappeared from radar cover at a height of 1400 feet and at a position 12 nautical miles (nm) from Islay/Port Ellen aerodrome on the 106° M radial. From the position that the aircraft descended below radar cover it is estimated that a direct track was flown towards the southern coast of the Isle of Islay. The flight continued at very low level parallel to the south coast. At 15:21 the Islay/Port Ellen radio operator transmitted further weather information which recorded that cloud conditions were similar to the previous report but that there was then heavy drizzle. Changes in barometric pressure settings were also reported. LC423 acknowledged this information and reported "over Port Ellen". However, the aircraft was not, at that time, over Port Ellen, but was in fact turning inland at very low level over Laphroaig. From overhead Laphroaig the aircraft settled on to a northwesterly heading and very shortly afterwards crashed into rising ground, that was obscured in hill fog, approximately 1 nm from the coast at a height of 360 feet amsl.

On approximately 25-May-1986, the aircraft landed on lake ice at Reliance, NWT; while taxiing the nose gear settled into a crack in the ice. The people of the community managed to prevent the aircraft from sinking further using pallets and empty drums. While the insurance company assessed methods of possibly removing the aircraft it continued to sink, eventually to a depth where only the tail remained above water. A military Chinook helicopter was eventually dispatched to Reliance, and it successfully lifted the aircraft out of the lake, and set it down in front of the weather station pending preparations to sling load it 143 nm to Yellowknife. After lift off, and a distance of approximately 200 yards the helicopter's load master elected to drop the aircraft, which plowed nose first into the lake, through the remaining lake ice. Some parts were salvageable and barged back to Yellowknife, however the aircraft was a total loss.
Text & photos : www.twinotterworld.com

The twin engine aircraft was cruising at an altitude of 8,500 feet in marginal weather conditions when it struck the slope of a mountain located about 18 km east of Tame, some 50 km south of Saravena. The aircraft was destroyed and all 13 occupants were killed.

The aircraft was observed flying at low altitude along about a 5 mile distance. Some witnesses described the aircraft altitude as just above treetops. Witness heard engine sounds and saw lights on the aircraft. The aircraft flight was on a southeast direction before it collided with rising terrain at a height of about 1,250 feet. The wreckage was scattered along a distance of 375 feet and oriented on a 160° magnetic heading. The destination, Pittsburgh, is located southwest of the departure point, State College. Evidence of aircraft malfunction was not disclosed. The aircraft had 1,902 lbs of cargo including 65 lbs of dry ice which was contained in styrofoam boxes. Autopsy and toxicological findings were negative. The pilot flew nightly, from State College to Pittsburgh and returned the following morning. He operated a business during the day. Witnesses stated the pilot was well rested and in good spirits before the flight.

Crashed shortly after takeoff from Mulia Airport for unknown reasons. Eight occupants were killed while 11 others were injured.

Aircraft crashed during missed approach to temporary winter landing strip. Aircraft hit in steep nose down attitude. Marginal weather conditions prevailed, with icing reported. All four occupants were injured, both pilots seriously.

En route from Quibdó to Medellín, the crew encountered marginal weather conditions with mist and intermittent rain falls. While cruising at an altitude of 11,500 feet, the aircraft struck the slope of Mt El Plateado located in the northeast part of the Chocó province, about 66 km northeast of Quibdó. The aircraft was destroyed upon impact and all 23 occupants were killed.