The following information provides an awareness of problems that might be avoided in the future. The information is based on final reports by official investigative authorities on aircraft accidents and incidents.
Jets
‘Conflicting Guidance’
Airbus A300-B4-622R. Minor damage. No injuries.
In an incident that “highlights the potentially serious consequences of attempting to go around after selection of reverse thrust,” the A300’s tail struck the runway as the aircraft struggled to become airborne with only one engine at full power, the other engine at idle and a thrust reverser partially deployed, said the U.K. Air Accidents Investigation Branch (AAIB).
The serious incident occurred the night of Jan. 10, 2011, at East Midlands Airport in Castle Donington, Leicestershire. The aircraft was inbound on a cargo flight from Belfast, Northern Ireland, with the commander as the pilot flying. Surface winds at the airport were from 160 degrees at 20 kt, gusting to 30 kt, visibility was 15 km (9 mi) in rain, the ceiling was broken at 1,500 ft, and the temperature was 7 degrees C (45 degrees F).
While preparing for the instrument landing system (ILS) approach to Runway 09, the flight crew selected an approach speed of 144 kt, which included an addition of 9 kt to the calculated landing reference speed (VREF) of 135 kt to compensate for the gusting crosswind.
“The commander stated that, as usual, he began to flare at about 30 ft AGL [above ground level] and, at about 20 ft AGL, closed the throttle control levers,” the AAIB report said. “However, he considered that the aircraft’s rate of descent was excessive and so increased the nose-up pitch.”
The aircraft bounced after touching down on the runway at 135 kt. “The commander reduced the pitch attitude slightly to allow the aircraft to settle back onto the runway, without reducing the thrust,” the report said. “The aircraft touched down again, heavily, before bouncing back into the air.”
Although neither pilot later recalled having selected reverse thrust, it likely was “an automatic and subconscious action by the commander,” said the report, noting that the flight crew operating manual (FCOM) states that the thrust reverse levers should be moved to the idle reverse position “immediately after touchdown of the main landing gear.”
After the second bounce, the commander decided to go around and moved the throttles to the takeoff position. This caused the no. 1 engine thrust reverser to stow automatically. However, the no. 2 engine thrust reverser failed to stow completely, and the engine was kept at idle thrust by the full authority digital engine control (FADEC) system.
“The main wheels remained on the ground for approximately two seconds, during which the aircraft pitched up from 5 degrees to 12.5 degrees, finally lifting off at an airspeed of 127 kt,” the report said. According to Airbus, a tail strike can occur at a pitch attitude of 11.2 degrees when the main landing gear struts are extended.
An airport traffic controller saw a shower of sparks emanate from the rear of the aircraft. “He described the aircraft appearing to fly very slowly over the runway during the go-around, rolling from side to side,” the report said. “He was sufficiently concerned that he pressed the crash alarm.”
With partial power, a partially deployed thrust reverser, low speed and the drag from the fully extended flaps, the A300 accelerated slowly. “The absence of high ground in the path of the aircraft was fortuitous, given the aircraft’s severely compromised performance,” the report said.
“Eventually, the speed started to increase, and [the commander] instructed the copilot to reduce the flap setting to ‘FLAP 20.’ The aircraft then started to climb, at which time the gear was raised; and, as the aircraft continued to accelerate, the flaps were retracted fully.”
The pilots then noticed a message on the electronic centralized aircraft monitor (ECAM) warning that the no. 2 thrust reverser was unlocked. The crew eventually shut down the no. 2 engine while completing the appropriate ECAM and quick reference handbook checklists. After reviewing weather conditions in the area, they decided to divert to London Stansted Airport, where the surface winds were from 170 degrees at 19 kt. They conducted a single-engine ILS approach to Stansted’s Runway 22 and landed without further incident.
Examination of the A300 revealed that the tail skid shoe was scraped and that the fuselage skin near the tail skid was dented and buckled. The no. 2 engine thrust reverser translating sleeves were found to be only about halfway closed.
“The investigation found that the most likely reason for the no. 2 thrust reverser failure to stow was an intermittent loose connection in the auto-restow circuit,” the report said. “It was further determined that conflicting operational guidance exists with respect to selection of reverse thrust and go-around procedures.”
Airbus had published flight operations briefing notes on bounce recovery and rejected landings in May 2005. The briefing notes, in part, emphasized an FCOM statement that the flight crew is committed to a full-stop landing after selecting reverse thrust because of the possibility of system damage when reverse thrust is canceled while the reversers are in transit to the deployed configuration. “The information further states that thrust asymmetry resulting from one thrust reverser failing to restow has led to instances of significantly reduced rates of climb or departure from controlled flight,” the report said. It noted that the operator of the incident aircraft had not distributed the information to its pilots, although the briefing notes were “freely available online.”
The report said that the briefing-note information conflicts with a separate FCOM requirement for initiation of a go-around following a “high” bounce on landing. However, the report noted that Airbus planned a June 2012 revision of the FCOM, “re-emphasizing the need, under all circumstances, to complete a full-stop landing if reverse thrust has been selected.”
Vibration Prompts Diversion
Boeing 737-800. Minor damage. No injuries.
The 737 was en route with 140 passengers and six crewmembers from Eindhoven, Netherlands, to Madrid, Spain, the morning of March 1, 2010, when the flight crew noticed an abnormal airframe vibration. They diverted the flight to Charleroi, Belgium, and landed the aircraft without further incident.
The aircraft was registered in Ireland, and Belgian authorities delegated the investigation of the serious incident to the Irish Air Accident Investigation Unit (AAIU). Investigators determined that the airframe vibration had been caused by oscillation of the elevator trim tab. Further examination of the trim system by Boeing, which manufactured the aircraft in 2008, revealed that the trim tab oscillation had been caused by accelerated wear of the bearing swage ring inside the attachment lug.
“The manufacturer determined that the bearing swage had worn because of ‘workmanship escapement and improper tool usage’ that would have occurred during component manufacture,” the AAIU report said.
“The manufacturer received a second report, from a different operator, of a severe elevator vibration event due to fractured aft attach lugs of the elevator tab control mechanism,” said the report.
Boeing issued a service bulletin (SB) prescribing inspections and conditions for replacement of existing elevator trim tab control mechanisms on affected 737s; these actions subsequently were mandated by an emergency airworthiness directive, 2010-17-19, issued by the U.S. Federal Aviation Administration (FAA).
“The manufacturer is in the process of redesigning the tab mechanism to address the problems identified,” said the AAIU report, issued in April. “An SB is being developed which installs a retention clip on the aft attach lugs of the tab mechanism; this should help to prevent future failures of the lugs.”
Contamination Causes Control Jam
Cessna 560XL. No damage. No injuries.
The Citation was nearing its cruise altitude of 41,000 ft during a charter flight from Naples, Florida, U.S., to Washington, D.C., the afternoon of Dec. 2, 2011, when the flight crew received a “pitch trim miscompare” advisory. “After accomplishing the checklist items and disconnecting the autopilot, the flight crew had to exert considerable forward yoke pressure to maintain level flight,” said the report by the U.S. National Transportation Safety Board (NTSB).
“The flight crew found the manual pitch trim control wheel to be ‘frozen’ in the forward position and were unable to move it,” the report said.
The crew declared an emergency, initiated a descent and diverted the flight to Orlando, Florida. After descending through 8,000 ft, the pitch trim control wheel released, and the trim system returned to normal operation. The crew canceled the emergency and landed the Citation at Orlando International Airport without further incident.
An inspection of the airplane by maintenance technicians revealed that the grease on both pitch-trim actuators was contaminated with water. Inspection and lubrication of the actuators is required every 1,200 hours. “According to the operator, the elevator trim actuators were last inspected and lubricated 562 hours prior to the incident,” the report said.
Undetected Data Default
Boeing 737-400. No damage. No injuries.
After receiving load information, the flight crew used an electronic flight bag (EFB) to perform takeoff performance calculations for the flight with 142 passengers and eight crewmembers from Melbourne, Victoria, Australia, to Brisbane, Queensland, the morning of Nov. 22, 2011. They initially prepared for a departure from Runway 27, which was 2,286 m (7,500 ft) long; however, after the aircraft was pushed back from the gate, the automatic terminal information system announced that the runway in use had been changed to Runway 16, which was 3,657 m (12,000 ft) long.
The crew decided to conduct a reduced-thrust takeoff from an intersection that provided 2,345 m (7,694 ft) of available takeoff distance on Runway 16. “The first officer, who was the pilot flying (PF), recalculated the takeoff performance figures using the EFB and, in doing so, inadvertently used the distance for the full length of Runway 16, which was the default field in the EFB after runway selection, rather than the planned [intersection] departure distance,” said the report by the Australian Transport Safety Bureau (ATSB).
The first officer handed the EFB to the captain, who also inadvertently used the default full distance while repeating the calculations. “The crew then cross-checked their calculation results, and, as both crew had made the same error, the figures were identical, and the opportunity to detect the mistake was missed,” the report said.
The calculations included 166 kt for V1, 171 kt for VR and 174 kt for V2, when the correct values for the intersection takeoff were 147 kt, 149 kt and 156 kt, respectively.
The captain, the pilot monitoring, realized that something was wrong with the takeoff data after the aircraft accelerated through 80 kt. “He subsequently called for the PF to rotate earlier than the nominated and displayed V1 speed,” the report said. “The recorded data shows the aircraft lifting off at around 165 kt. The crew reported the aircraft climbed away normally.”
The pilots told investigators that they had not felt rushed during their preflight preparations. “Both crew reported having enough time to conduct the preflight preparations and to make the amendments to the EFB after pushback,” the report said. “They also reported no distractions or interruptions from air traffic control or the cabin and no time pressure during the taxi to the runway.”
Among actions taken by the aircraft operator after the incident was an EFB modification deleting the full-runway-length default and requiring the user to select full length or an intersection.
“Errors in the calculation, entry and checking of data are not uncommon in the airline operating environment,” said the report, noting that ATSB in January 2011 issued the results of research on factors that contribute to such errors (see, “Safety in Numbers”).
Belly Hits Runway on Go-Around
Eclipse Aviation 500. Substantial damage. No injuries.
The pilot knew that the flap-extension system was inoperative before beginning a private flight with one passenger from Anadyr, Russia, to Nome, Alaska, U.S. En route stops in Japan and Korea were uneventful, and visual meteorological conditions (VMC) prevailed when the Eclipse reached Nome the night of June 1, 2011. The pilot conducted a visual approach to Runway 10, which was 6,000 ft (1,829 m) long.
He told investigators that he noticed the airspeed was “exceptionally high” during the approach but decided to continue. “On short final to the runway, he realized that he was not going to be able to land and decided to go around,” the NTSB report said.
The fuselage struck the runway during the go-around, but the pilot was able to continue flying the airplane. While returning to the runway, he realized that he had not extended the landing gear during the first approach. “He then lowered the landing gear and landed the airplane uneventfully,” the report said.
The pilot noticed only a broken antenna and scrapes on the fuselage skid pad; however, he decided to conduct a test flight before boarding his passenger the next morning. “During the takeoff roll, the airplane encountered a vibration that the pilot said felt ‘like a violent nosewheel shimmy,’” the report said. “He aborted the takeoff and elected to have the airplane inspected by a mechanic, [who] discovered that the center wing carry-through structure [had been] cracked when the belly skid pad deflected upward into a stringer that the structure was attached to.”
Investigators found that the flap-extension system failure had been caused by overtravel of the inboard flap actuator during a flap retraction. The report noted that the EA 500 flight manual prohibits flight with an inoperative flap-extension system.
Turboprops
Looking for the Runway
Xian MA60. Destroyed. 25 fatalities.
The flight crew persisted in conducting a visual approach in weather conditions that were not suitable for visual flight rules (VFR) flight, and, during the subsequent go-around, they were still looking for the runway when the aircraft entered a steep turn and descended into the sea, said the Indonesian National Transportation Safety Committee in its final report on the May 7, 2011, accident at Kaimana, West Papua, New Guinea.
The accident occurred during a scheduled flight to Kaimana from Sorong, both on the west coast of New Guinea. The report said that both pilots had relatively low time in type. The captain, 55, had logged about 200 of his 24,470 flight hours in MA60s. The copilot, 36, had 370 flight hours, including 234 hours in type.
Kaimana does not have an instrument approach procedure or any navigational aids, and the crew learned before beginning descent that visibility at the uncontrolled airport was 3 to 8 km (2 to 5 mi) in rain and that the ceiling was broken at 1,500 ft. As the aircraft neared Kaimana, the aerodrome flight information service officer told the crew that visibility at the airport had dropped to 2 km (1 1/4 mi) in heavy rain but that the weather south of the airport was clear.
The captain told the copilot, the PF, to continue on a southerly heading, paralleling the coastline and flying past the airport. The captain gave heading, airspeed, altitude and power setting instructions as the copilot made a wide left turn over the water and rolled out on a northerly heading, roughly aligned with the 1,600-m (5,250-ft) runway. The enhanced ground-proximity warning system (EGPWS) generated an aural “minimum, minimum” warning as the aircraft descended below 500 ft AGL.
The MA60 was nearing the coastline south of the airport when the captain assumed control. He asked the copilot three times if he had the runway in sight. After the copilot replied, for the third time, that the runway was not in sight, the captain initiated a go-around.
The aircraft was at 376 ft (250 ft AGL) when the captain moved the power levers forward. However, because the crew had not conducted an approach briefing or the approach and landing checklists, the engine regime selector was still set to “CRUISE,” rather than to “TOGA” (takeoff/go-around); and the torque produced by the left and right engines increased to 70 percent and 82 percent, respectively, rather than to about 95 percent, the report said. The captain began a left turn toward the sea, apparently to avoid high terrain east of the airport, and the flaps and the landing gear were retracted as the aircraft began to climb.
The report said that both pilots likely were preoccupied with looking for the runway as the left bank angle increased from 11 degrees to 33 degrees. The MA60 climbed about 200 ft, and airspeed was 124 kt when it began to descend rapidly, with the bank angle increasing to 38 degrees. The descent rate increased to about 3,000 fpm, and the EGPWS generated a “terrain, terrain” warning just before the aircraft struck the water about 800 m (2,625 ft) southwest of the runway. All aboard — the 19 passengers, two engineers, two flight attendants and the pilots — were killed.
Cellphone Battery Emits Smoke
Saab 340B. No damage. No injuries.
The aircraft was being taxied to the gate after landing in Sydney, New South Wales, Australia, on Nov. 25, 2011, when a cabin crewmember noticed smoke accumulating near a passenger seat. The crewmember “instructed the passenger to throw the source of the smoke into the aisle [and] then discharged a fire extinguisher onto what was later identified as a mobile telephone,” the ATSB report said. “After several minutes, the smoke cleared.”
Examination of the cellphone revealed that a small metal screw, likely misplaced in the battery bay during a screen repair by an unauthorized service facility six months earlier, had punctured the lithium battery casing, causing an internal short circuit that led to heating and thermal runaway, the report said.
The report said that the incident was a “first of its type” in Australia that “highlights the risks associated with the use of nonauthorized agents for the repair of lithium battery-powered devices and reinforces Civil Aviation Safety Authority recommendations that these devices should be carried in the cabin and not in checked-in baggage.”
Illusion Suspected in Tanker Crash
Convair 580. Destroyed. Two fatalities.
The flight crew circled the tanker while watching the crew of a “bird dog” Rockwell 690, which has operating speeds similar to those of the Convair, demonstrate the maneuvering required to drop retardant on a wildfire in Lytton, British Columbia, Canada, on July 31, 2010. “The bombing run required crossing the edge of a ravine in the side of the Fraser River canyon before descending on the fire located in the ravine,” said the report by the Transportation Safety Board of Canada (TSB).
The established minimum altitude to cross the ravine was 3,100 ft, which provided about 100 to 150 ft of clearance above the trees on the edge of the ravine. A 90-degree left turn and a 900-ft descent into the ravine then were required to position the aircraft for the drop.
The Convair was near its maximum operating weight as it descended for its first drop. The crew flew the aircraft parallel to the edge of the ravine and made a descending left turn toward the rising terrain leading to the edge of the ravine. The Rockwell crew saw the Convair strike trees atop the edge of the ravine, jettison retardant, enter a steep bank and spin to the bottom of the ravine.
Examination of the accident site indicated that the Convair was climbing through 3,020 ft when it struck the trees and that both engines were producing maximum power. Investigators determined that, while approaching the upsloping terrain, the pilots might have experienced a visual illusion that the aircraft was higher that it actually was and that the resulting spatial disorientation “may have precluded recognition, or an accurate assessment, of the flight path profile in sufficient time to avoid the trees on the rising terrain.”
“When the bombing run flight path was flown by TSB investigators several weeks after the accident, a visual illusion was observed,” the report said. “During the combined downwind/base leg at 3,100 ft to 3,200 ft, proceeding toward the known site of the initial tree strikes, estimated 1 nm [2 km] away, the site appeared to be about 400 ft to 500 ft below the aircraft altitude, when it was actually 150 ft below.” The report noted that the test flight was conducted in “good daytime visual conditions,” while the accident occurred one hour before sunset with visibility between 6 and 9 mi (10 and 14 km).
Piston Airplanes
Flaps, Gear Down on Departure
Cessna 421B. Destroyed. Five fatalities.
Dark night VMC prevailed when the 421 struck terrain while departing from Alpine, Texas, U.S., for an emergency medical services flight on July 4, 2010. The pilot, two flight nurses, the patient and a passenger were killed in the crash, which occurred at 0015 local time.
“Examination of the ground scars and wreckage indicated that the landing gear was down, the flaps were down and the engines were operating at a high power setting at the time of impact,” the NTSB report said.
The safety board concluded that the probable cause of the crash was the “degraded performance of the airplane” that resulted because the pilot had not properly set the flaps before takeoff and had not retracted the landing gear after takeoff.
“Although the investigation was unable to determine how long the pilot had been awake before the accident or his sleep schedule in the three days prior to the accident, it is possible that the pilot was fatigued, as the accident occurred at a time when the pilot was normally asleep,” the report said.
Control Lost in Turbulence
De Havilland DHC-2. Substantial. One fatality.
After a cargo flight the morning of July 23, 2010, the pilot was returning to his home base in Ketchikan, Alaska, U.S., which had low clouds, rain and surface winds gusting to 40 kt. The pilot requested a special VFR clearance into the Class E airspace surrounding the airport and was told by a flight service specialist to remain clear of the area until the clearance could be issued, the NTSB report said.
When the specialist radioed the pilot about eight minutes later to issue the clearance, there was no response. A company dispatcher, who was monitoring the float-equipped Beaver’s progress on a moving-map display, saw the airplane enter a holding pattern about 5 nm (9 km) from the airport and then disappear from the display soon thereafter.
A witness saw the airplane flying very low over treetops. “He said that as the airplane passed overhead, it turned sharply to the left,” the report said. “As he watched the airplane, the wings rocked violently from side to side, and the nose pitched up and down. As the airplane passed low over hilly, tree-covered terrain, it rolled to the right, the right wing struck a large tree and separated, and the airplane rolled inverted and descended [out of sight] behind a stand of trees.”
NTSB determined that the probable cause of the accident was “the pilot’s decision to continue the flight toward his destination in significant turbulence and downdrafts, and his subsequent failure to maintain control of the airplane while flying low over rising terrain.”
Helicopters
Gull Shatters Windshield
Agusta A109C. Substantial damage. One minor injury.
The Agusta was at 750 ft AGL and cruising at 150 kt when a bird struck and shattered the left windshield the morning of July 5, 2011. “The commander, who was flying the helicopter from the left seat, was struck by pieces of windshield and parts of the bird,” the AAIB report said. The copilot assumed control, declared an emergency and landed the helicopter in a field near Kew Bridge, England.
The bird was identified as a herring gull, which typically weighs 690 to 1,495 g (24 to 53 oz).
The A109C was certified in 1989 under U.S. Federal Aviation Regulations Part 27, the airworthiness standards for normal category rotorcraft. The report said that unlike Part 29, which requires the windshields on transport category rotorcraft to meet specific standards for bird strike resistance, Part 27 — and its European Aviation Safety Agency (EASA) counterpart, Certification Specification 27 — require only that “windshields and windows must be made of material that will not break into dangerous fragments.”
The report noted, however, that the FAA and EASA currently are reviewing recommendations to revise normal category rotorcraft windshield requirements.
Loose Cover Hits Rotor Blades
Eurocopter AS350-B3. Substantial damage. No injuries.
After completion of a 100-hour maintenance inspection in Aurora, Oregon, U.S., the afternoon of July 27, 2011, the pilot was conducting a positioning flight with three passengers to the helicopter’s home base in Dallesport, Washington, when he “felt something that he described as similar to a bird strike,” the NTSB report said.
The pilot made a precautionary landing at the Portland-Troutdale (Oregon) Airport and found that a portion of the tail rotor drive shaft cover was missing and that one main rotor blade and two tail rotor blades were damaged.
Investigators determined that the cover had not been secured properly during the maintenance inspection. The company’s director of maintenance said that the maintenance technicians who had performed the inspection and the pilot likely had “looked at the cover before the accident flight and presumed that it was secure or had been secured by someone else.”
Pole Struck While Taxiing
Aerospatiale AS332-L1. Substantial damage. Five minor injuries.
The helicopter was returning to Port Keats Airport, Northern Territory, Australia, during a round-trip charter flight to an offshore platform the afternoon of July 21, 2011, when the flight crew saw two Swearingen Metroliners on the apron where they had intended to park.
After landing, the pilot decided to taxi the Super Puma past the Metroliners and park it at the far corner of the apron. “His focus was directed to maintaining adequate clearance from the aircraft wing tip on his right, while directing the copilot [in the left seat] to ensure there was adequate clearance from a light pole to the left of the helicopter,” the ATSB report said.
The helicopter toppled onto its left side when the main rotor blades struck the light pole. The pilots and three of the four passengers sustained minor injuries but were able to exit upward through the right side windows. A baggage handler and two people in a parked vehicle received minor injuries from flying debris; and three other vehicles and one of the Metroliners were damaged.
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