Crash of a De Havilland DHC-6 Twin Otter 100 in La Ronge

Date & Time: Feb 4, 2009 at 0915 LT
Operator:
Registration:
C-FCCE
Flight Phase:
Survivors:
Yes
Schedule:
La Ronge – Deschambeault Lake
MSN:
8
YOM:
1966
Country:
Crew on board:
2
Crew fatalities:
Pax on board:
5
Pax fatalities:
Other fatalities:
Total fatalities:
0
Captain / Total flying hours:
14000
Captain / Total hours on type:
11000.00
Copilot / Total flying hours:
625
Copilot / Total hours on type:
425
Circumstances:
The aircraft was taking off from a ski strip east of and parallel to Runway 36 at La Ronge. After the nose ski cleared the snow, the left wing rose and the aircraft veered to the right and the captain, who was the pilot flying, continued the take-off. The right ski, however, was still in contact with the snow. The aircraft became airborne briefly as it cleared a deep gully to the right of the runway. The aircraft remained in a steep right bank and the right wing contacted the snow-covered ground. The aircraft flew through a chain link fence and crashed into trees surrounding the airport. The five passengers and two crewmembers evacuated the aircraft with minor injuries. There was a small fire near the right engine exhaust that was immediately extinguished by the crew.
Probable cause:
Findings as to Causes and Contributing Factors:
1. Contamination on the wings of the aircraft was not fully removed before take-off. It is likely that asymmetric contamination of the wings created a lift differential and a loss of lateral control.
2. Although the operator was not authorized for short take-off and landing (STOL) take-off on this aircraft, the crew conducted a STOL take-off, which reduced the aircraft’s safety margin relative to its stalling speed and minimum control speed.
3. As a result of the loss of lateral control, the slow STOL take-off speed, and the manipulation of the flaps, the aircraft did not remain airborne and veered right, colliding with obstacles beside the ski strip.
Findings as to Risk:
1. The out of phase task requirements regarding the engine vibration isolator assembly, as listed in the operator’s maintenance schedule approval, results in a less than thorough inspection requirement, increasing the likelihood of fatigue cracks remaining undetected.
2. The right engine inboard and top engine mounts had pre-existing fatigue cracks, increasing the risk of catastrophic failure.
Other Findings:
1. The cockpit voice recorder (CVR) contained audio of a previous flight and was not in operation during the occurrence flight. Minimum equipment list (MEL) procedures for logbook entries and placarding were not followed.
2. The Transwest Air Limited safety management system (SMS) did not identify deviations from standard operating procedures.
Final Report:

Crash of a De Havilland DHC-6 Twin Otter 300 in Lukla: 18 killed

Date & Time: Oct 8, 2008 at 0731 LT
Operator:
Registration:
9N-AFE
Survivors:
Yes
Schedule:
Kathmandu – Lukla
MSN:
720
YOM:
1980
Country:
Region:
Crew on board:
3
Crew fatalities:
Pax on board:
16
Pax fatalities:
Other fatalities:
Total fatalities:
18
Captain / Total flying hours:
8185
Captain / Total hours on type:
7180.00
Copilot / Total flying hours:
556
Copilot / Total hours on type:
341
Circumstances:
The aircraft departed Kathmandu-Tribhuvan Airport at 0651LT on a regular schedule service to the Lukla-Tenzing-Hillary Airport. On approach to runway 06, the crew encountered poor visibility due to foggy conditions. Despite the pilot did not establish any visual contact with the ground, he continued the approach when, on short final, the aircraft struck a rock and crashed just below the runway 06 threshold, bursting into flames. The captain was seriously injured while 18 other occupants were killed, among them 12 Germans, 2 Australians and 5 Nepalese.
Probable cause:
Controlled flight into terrain after the captain decided to continue the approach under VFR mode in IMC conditions.

Crash of a De Havilland DHC-6 Twin Otter 300 off North Ari Atoll

Date & Time: Jul 14, 2008 at 1230 LT
Operator:
Registration:
8Q-MAS
Survivors:
Yes
Schedule:
Male - North Ari Atoll
MSN:
445
YOM:
1975
Region:
Crew on board:
3
Crew fatalities:
Pax on board:
14
Pax fatalities:
Other fatalities:
Total fatalities:
0
Captain / Total flying hours:
3150
Captain / Total hours on type:
430.00
Copilot / Total flying hours:
2880
Copilot / Total hours on type:
127
Aircraft flight hours:
49129
Circumstances:
14th July 2008 was a Monday; the busiest day of the week where there is an average of 150-200 movements. 8Q-MAS completed six sectors prior to the accident, with the same flight crew. Sixteen pieces of baggage were loaded, in the aft cabin, with total weight of 458 lbs. The flight manifest signed by Pilot in Command indicated that the aircraft was loaded up to 11874 lbs. The aircraft was boarded with 14 passengers (7 females, 6 males and 1 child) and the flight manifest used approved weights of 77 lbs Child, 181 lbs for male and 141 lbs for female to calculate the aircraft weight. The aircraft had 930 lbs of fuel. This particular aircraft was a short nose twin otter aircraft, with main loading in aft cabin. The MAT seaplane operation was based on a day VFR, non-schedule and a self dispatch system. All pre-flight duties were completed by the crew. The weather was windy and sea was rough. The aircraft departed at 12.11 hrs from MAT dock at Male International Airport, Water Aerodrome to Adaaran Club Bathala with 14 passengers total: 10 passengers to Adaaran Club Bathala, 2 passengers to Nika Maldives and 2 Passengers to W Retreat and Spa (Fesdu). The estimated flight time to destination was 20 minutes. The W Retreat and Spa Maldives Resort’s Speed Boat (Angelina) (a 34 ft Triana Express) was moored at a buoy (located at 04 04’ 43.6” N, 072 56’ 37.1” E) used by MAT to moor the aircrafts for night stops. The floating platform was located (04 04’ 43.5”N, 072 56’ 38.8”E) east of the buoy. The distance between the floating platform and buoy is around 165 feet. Around 12:30 the aircraft approached for landing near the floating platform. The wind was on a westerly direction 20 to 25 knots and the aircraft approached for a westbound landing. The aircraft made an orbit over the lagoon to inspect the water. The aircraft did a touchdown and was cutting the wave tops to find an appropriate location to stop, when it hit a big wave and was airborne. The aircraft veered to the left. The PIC declared to do a go around. The crew action was 10 degree flap, full throttle and Max Prop RPM. On climb the aircraft collided with the Speed Boat and the aircraft veered to the right and PIC was able to land on LH float.
Probable cause:
Causal Factors:
• The crew’s decision to land on rough waters without giving due considerations for a rejected landing and obstacles nearby was a causal factor.
• The Speed Boat moored to a buoy, close to the landing area was also a causal factor.
Final Report:

Crash of a De Havilland DHC-6 Twin Otter 300 near Cochamó: 3 killed

Date & Time: Jul 2, 2008 at 1430 LT
Operator:
Registration:
947
Flight Phase:
Flight Type:
Survivors:
No
Site:
Schedule:
Puerto Montt - Puerto Montt
MSN:
404
YOM:
1974
Country:
Crew on board:
3
Crew fatalities:
Pax on board:
0
Pax fatalities:
Other fatalities:
Total fatalities:
3
Circumstances:
The crew departed Puerto Montt-El Tepual for a training flight. En route, the twin engine aircraft collided with the cables of a 23,000 volts powerline and crashed on a hilly terrain, bursting into flames. All three crew members were killed.

Crash of a De Havilland DHC-6 Twin Otter 100 in Hyannis: 1 killed

Date & Time: Jun 18, 2008 at 1001 LT
Operator:
Registration:
N656WA
Flight Phase:
Flight Type:
Survivors:
No
Schedule:
Hyannis - Nantucket
MSN:
47
YOM:
1967
Flight number:
WIG6601
Crew on board:
1
Crew fatalities:
Pax on board:
0
Pax fatalities:
Other fatalities:
Total fatalities:
1
Captain / Total flying hours:
3607
Captain / Total hours on type:
99.00
Aircraft flight hours:
38185
Circumstances:
The pilot contacted air traffic control and requested clearance to taxi for departure approximately an hour after the scheduled departure time. About 4 minutes later, the flight
was cleared for takeoff. A witness observed the airplane as it taxied, and found it strange that the airplane did not stop and "rev up" its engines before takeoff. Instead, the airplane taxied into the runway and proceeded with the takeoff without stopping. The airplane took off quickly, within 100 yards of beginning the takeoff roll, became airborne, and entered a steep left bank. The bank steepened, and the airplane descended and impacted the ground. Post accident examination of the wreckage revealed that the pilot's four-point restraint was not fastened and that at least a portion of the cockpit flight control lock remained installed on the control column. One of the pre-takeoff checklist items was, "Flight controls - Unlocked - Full travel." The airplane was not equipped with a control lock design, which, according to the airframe manufacturer's previously issued service bulletins, would "minimize the possibility of the aircraft becoming airborne when take off is attempted with flight control locks inadvertently installed." In 1990, Transport Canada issued an airworthiness directive to ensure mandatory compliance with the service bulletins; however, the Federal Aviation Administration did not follow with a similar airworthiness directive until after the accident.
Probable cause:
The pilot's failure to remove the flight control lock prior to takeoff. Contributing to the accident was the Federal Aviation Administration's failure to issue an airworthiness directive making the manufacturer's previously-issued flight control lock service bulletins mandatory.
Final Report:

Crash of a De Havilland DHC-6 Twin Otter 300 in Sidra

Date & Time: Jun 8, 2008
Operator:
Registration:
5A-DAU
Flight Type:
Survivors:
Yes
Schedule:
Sidra - Sidra
MSN:
570
YOM:
1977
Country:
Region:
Crew on board:
2
Crew fatalities:
Pax on board:
0
Pax fatalities:
Other fatalities:
Total fatalities:
0
Circumstances:
The crew was completing a local training flight at Sidra Airport when the accident occurred in unknown circumstances. The aircraft came to rest in a sandy area with its undercarriage and left wing sheared off. Both pilots evacuated safely.

Crash of a De Havilland DHC-6 Twin Otter 200 in Comodoro Rivadavia

Date & Time: Apr 4, 2008
Operator:
Registration:
T-84
Flight Phase:
Flight Type:
Survivors:
Yes
MSN:
214
YOM:
1969
Country:
Crew on board:
2
Crew fatalities:
Pax on board:
4
Pax fatalities:
Other fatalities:
Total fatalities:
0
Circumstances:
Shortly after takeoff from Comodoro Rivadavia Airport, while climbing, the crew encountered an unexpected situation and was forced to attempt an emergency landing. The aircraft crash landed in a desert area located about 10 km from the airport. While all six occupants escaped uninjured, the aircraft was damaged beyond repair.

Crash of a De Havilland DHC-6 Twin Otter 310 near Punia

Date & Time: Aug 31, 2007 at 1300 LT
Operator:
Registration:
ZS-NJK
Flight Phase:
Flight Type:
Survivors:
Yes
Schedule:
Punia - Goma
MSN:
598
YOM:
1978
Location:
Region:
Crew on board:
2
Crew fatalities:
Pax on board:
0
Pax fatalities:
Other fatalities:
Total fatalities:
0
Circumstances:
The crew departed Punia on a ferry flight to Goma. About 10 minutes into the flight, while cruising at a relative low altitude, the aircraft collided with power lines. The crew attempted an emergency landing when the aircraft crashed in the Lowa River located about 30 km northeast of Punia, coming to rest upside down. Both pilots escaped with minor injuries while the aircraft was damaged beyond repair.

Crash of a De Havilland DHC-6 Twin Otter 300 off Moorea: 20 killed

Date & Time: Aug 9, 2007 at 1201 LT
Operator:
Registration:
F-OIQI
Flight Phase:
Survivors:
No
Schedule:
Moorea – Papeete
MSN:
608
YOM:
1979
Flight number:
QE1121
Location:
Region:
Crew on board:
1
Crew fatalities:
Pax on board:
19
Pax fatalities:
Other fatalities:
Total fatalities:
20
Captain / Total flying hours:
3514
Captain / Total hours on type:
298.00
Aircraft flight hours:
30833
Aircraft flight cycles:
55044
Circumstances:
On Thursday 9 August 2007, the DHC-6 aeroplane registered F-OIQI was scheduled to fly a public transport flight (QE1121) between Moorea and Tahiti Faa’a with a pilot and 19 passengers on board. The flight, with an average duration of 7 minutes, is performed under VFR at a planned cruise altitude of 600 feet. The following information is derived from the on-board audio recording and witness statements. At 21 h 53 min 22, startup was authorised. The pilot made the safety announcement in English and in French: “Ladies and Gentlemen, hello and welcome on board. Please fasten your seatbelts”. At 21 h 57 min 19, the air traffic controller cleared the aeroplane to taxi towards holding point Bravo on runway 12. At 21 h 58 min 10, the aeroplane was cleared to line up. It taxied up the runway and lined up at the level of the second taxiway. At 22 h 00 min 06, the aeroplane was cleared for takeoff. Six seconds later the engines were powered up. At 22 h 00 min 58, the pilot retracted the flaps. At 22 h 01 min 07, propeller speed was reduced. At 22 h 01 min 09 the pilot uttered an expression of surprise. Two GPWS warnings sounded, propeller speed increased and four further GPWS warnings sounded. The aeroplane struck the surface of the sea at 22 h 01 min 20. One minute and eight seconds elapsed between engine power-up and the end of the audio recording. Fourteen bodies were recovered during the rescue operations. Some aeroplane debris, including parts of the right main gear and seat cushions were recovered by fishermen and the rescue team. Some days later, at a depth of seven hundred metres, a fifteenth body was recovered during operations to recover the flight recorder, both engines, the instrument panel, the front part of the cockpit including engine and flaps controls, the flaps jackscrews and the tail section. It was noted that the rudder and elevator control cables were broken off in their forward parts and that the elevator pitch-up control cable had, in its aft part, a second failure whose appearance was different from that observed on the other failures that were examined.
Probable cause:
The accident was caused by the loss of airplane pitch control following the failure, at a low height, of the elevator pitch-up control cable at the time the flaps were retracted. This failure was due to the following series of phenomena:
- Significant wear on the cable in line with a cable guide;
- An external phenomenon, most likely jet blast, which caused the failure of several strands;
- The failure of the last strand or strands under in-flight loads on the elevator control system.
The following factors may have contributed to the accident:
- The absence of information and training for pilots on a loss of pitch control;
- The operator’s failure to carry out some special inspections;
- The failure by the manufacturer and the airworthiness authority to fully take into account the wear phenomenon;
- The failure by the airworthiness authorities, airport authorities and operators to fully take into account the risks associated with jet blast;
- The rules for replacement of stainless steel cables on a calendar basis, without taking into account the activity of the airplane in relation to its type of operation.
Final Report:

Crash of a De Havilland DHC-6 Twin Otter 100 in Muncho Lake: 1 killed

Date & Time: Jul 8, 2007 at 1235 LT
Operator:
Registration:
C-FAWC
Flight Phase:
Survivors:
Yes
Schedule:
Muncho Lake – Prince George
MSN:
108
YOM:
1968
Country:
Crew on board:
2
Crew fatalities:
Pax on board:
3
Pax fatalities:
Other fatalities:
Total fatalities:
1
Captain / Total flying hours:
22000
Captain / Total hours on type:
6000.00
Copilot / Total flying hours:
10800
Copilot / Total hours on type:
105
Circumstances:
At approximately 1235 Pacific daylight time, the Liard Air Limited de Havilland DHC-6-100 Twin Otter (registration C-FAWC, serial number 108) was taking off from a gravel airstrip near the Northern Rockies Lodge at Muncho Lake on a visual flight rules flight to Prince George, British Columbia. After becoming airborne, the aircraft entered a right turn and the right outboard flap hanger contacted the Alaska Highway. The aircraft subsequently struck a telephone pole and a telephone cable, impacted the edge of the highway a second time, and crashed onto a rocky embankment adjacent to a dry creek channel. The aircraft came to rest upright approximately 600 feet from the departure end of the airstrip. An intense post-impact fire ensued and the aircraft was destroyed. One passenger suffered fatal burn injuries, one pilot was seriously burned, the other pilot sustained serious impact injuries, and the other two passengers received minor injuries.
Probable cause:
Findings as to Causes and Contributing Factors:
1. The take-off was attempted at an aircraft weight that did not meet the performance capabilities of the aircraft to clear an obstacle and, as a result, the aircraft struck a telephone pole and a telephone cable during the initial climb.
2. A take-off and climb to 50 feet performance calculation was not completed prior to take-off; therefore, the flight crew was unaware of the distance required to clear the telephone cable.
3. The southeast end of the airstrip was not clearly marked; as a result, the take-off was initiated with approximately 86 feet of usable airstrip behind the aircraft.
4. The take-off was attempted in an upslope direction and in light tailwind, both of which increased the distance necessary to clear the existing obstacles.
Findings as to Risk:
1. Operational control within the company was insufficient to reduce the risks associated with take-offs from the lodge airstrip.
2. The take-off weight limits for lodge airstrip operations were not effectively communicated to the flight crew.
3. Maximum performance short take-off and landing (MPS) techniques may have been necessary in order to accomplish higher weight Twin Otter take-offs from the lodge airstrip; however, neither the aircraft nor the company were approved for MPS operations.
4. The first officer’s shoulder harness assembly had been weakened by age and ultraviolet (UV) light exposure; as a result, it failed within the design limits at impact.
5. The SeeGeeTM calculator operating index (OI) values being used by Liard Air Twin Otter pilots was between 0.5 and 1.0 units greater than the correct SeeGeeTM OI values; therefore, whenever the SeeGeeTM calculator was used for flight planning, the actual centre of gravity (c of g) of the aircraft would have been forward of the calculated CofG.
6. There are no airworthiness standards specifically intended to contain fuel and/or to prevent fuel ignition in crash conditions in fixed-gear United States Civil Aviation Regulation 3 and United States Federal Aviation Regulation 23 aircraft.
Final Report: