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.
Boeing 777-300. No damage. No injuries.
The tower controller at Melbourne Airport in Victoria, Australia, noticed that the 777 was lower than it should have been and advised the flight crew to check their altitude. Receiving no immediate response, the controller told the crew to go around. However, nearly a minute elapsed before the aircraft began to climb. The crew completed the go-around and landed without further incident.
During its investigation of the incident, the Australian Transport Safety Bureau (ATSB) determined that the pilot-in-command (PIC) “may not have fully understood some aspects of the aircraft’s automatic flight control systems and probably experienced ‘automation surprise’” when the autopilot commanded an unexpected pitch change during the nonprecision approach.
Moreover, the ATSB’s final report said that the crew’s delay in complying with the controller’s go-around instruction “could have resulted in a more hazardous situation” if, for instance, the instruction had been issued because of terrain or traffic, rather than because the aircraft was unusually low on final approach.
The incident occurred the night of July 24, 2011, during a passenger flight to Melbourne from Bangkok, Thailand. The first officer was the pilot flying.
The 777 was nearing Melbourne at 6,000 ft when the approach controller told the crew to descend to 3,000 ft and issued a vector to establish the aircraft on the VOR (VHF omnidirectional range) approach to Runway 34.
“Weather reports indicated that visual meteorological conditions existed at the time and visibility was reduced to about 8 km [5 mi] due to rain showers,” the report said. “The wind was reported to be from the north at about 20 kph [11 kt].”
The descent was conducted with the autopilot’s lateral navigation (LNAV) and vertical navigation speed (VNAV SPD) modes selected, and with 230 kt and 3,000 ft set in the mode control panel (MCP). “In [VNAV SPD] mode, the autoflight system acted to maintain the selected airspeed of 230 kt and limit the descent to not below 3,000 ft,” the report said.
The published minimum altitude between the initial approach fix and the intermediate approach fix was 3,000 ft. However, the aircraft’s flight management computer (FMC) had computed a final glide path that began at 3,440 ft, to enable descent on a constant 3-degree glide path, rather than the consecutive “step-downs” at the intermediate approach fix and the final approach fix, to the minimum descent altitude (MDA).
The 777 was descending through 3,300 ft as it neared the intermediate approach fix, and the autopilot automatically changed from the VNAV speed mode to the VNAV flight path mode, to follow the computed approach path. “As the FMC-calculated approach path altitude was about 3,400 ft and above the aircraft’s current altitude, the [autopilot] commanded a pitch-up to level flight for interception of the required approach path,” the report said.
Although the flight crew had conducted similar coupled approaches before, the pitch-up in this case apparently was more pronounced. “While the [PIC] reported that he had not observed this type of [autopilot] behaviour before, it was possible that during previous approaches, the aircraft was already on or above the required approach path,” the report said. “In that case, any pitch change would have been minimal.”
The PIC apparently was expecting the aircraft to level off at 3,000 ft, and the unexpected pitch-up at 3,300 ft caused him to suspect a fault in the autopilot VNAV mode. He reacted by setting 2,000 ft and 190 kt in the MCP and selecting the autopilot flight change mode. “While it was likely that those actions were intended to arrest the pitch change and continue the descent, they were symptomatic of ‘automation surprise’ on the part of the PIC, probably due to a lack of [autopilot] mode appreciation,” the report said.
In flight change mode, the autopilot adjusts the pitch attitude to maintain the speed selected on the MCP. “In that mode, the aircraft’s rate of descent is unrestricted and therefore may be significantly higher than that required for an instrument approach,” the report said.
To maintain the selected airspeed of 190 kt down to 2,000 ft, the autothrottle reduced engine thrust to flight idle. At this point, the crew inadvertently set 970 ft (the MDA) in the MCP, which caused the aircraft to prematurely descend below 1,950 ft, the published minimum altitude between the initial approach fix and the final approach fix.
Shortly thereafter, the PIC established radio communication with the airport tower controller and reported the airport in sight. The tower controller cleared the crew to conduct a visual approach if the aircraft was established on the precision approach path indicator (PAPI) glide path and was inside the “circling area.” At the time, the aircraft was below the PAPI glide path and nearly 2 nm (4 km) outside the circling area.
The PIC momentarily lost sight of the runway when the aircraft encountered a rain shower. He then noticed four red PAPI lights, indicating that the 777 was substantially below the 3-degree glide path, and told the first officer to stop the descent. The first officer disengaged the autopilot and leveled the aircraft.
About the same time, “the tower controller observed both visually and by radar that the aircraft was low on the approach and asked the flight crew to ‘check altitude,’” the report said. “Four seconds later, the controller instructed the crew to ‘climb, go around, carry out missed approach Runway 34,’ to which the flight crew responded ‘climbing.’”
The aircraft was still outside the final approach fix and at 984 ft (966 ft below the minimum segment altitude) when the controller issued the instruction to go around. Although the missed approach procedure called for an initial climb to 4,000 ft, the aircraft climbed only to about 1,200 ft.
About 50 seconds later, the controller asked the crew to confirm that they were conducting a go-around. The PIC replied, “We are climbing. … We are maintaining 1,200.”
The tower controller again told the crew to go around. The PIC’s response was mostly incomprehensible but included the words “on visual approach.”
“Negative,” the controller said. “Missed approach Runway 34. Climb to 4,000 ft.” The crew complied with the instruction, conducted another VOR approach with the autopilot LNAV and VNAV modes engaged and landed the aircraft on Runway 34.
The report said, “This occurrence highlights the risks inherent in the conduct of nonprecision approaches and reinforces the need for flight crews to closely monitor the aircraft’s flight path to ensure it complies with the prescribed procedure.”
Noting that errors in the use of automatic flight control systems have been identified as causal factors in 20 percent of approach-and-landing accidents worldwide, the report said, “Modern air transport aircraft are equipped with ever-increasing levels of automation that, when used appropriately, can greatly reduce flight crew workload. While flight crews retain the option of flying the aircraft manually, the use of automation is generally preferred and often provides increased levels of safety and efficiency. To effectively manage the aircraft and flight path, however, flight crews need to maintain a thorough understanding of the relevant automatic flight systems.”
The airline responded to the incident by issuing a notice to flight crews emphasizing the importance of constant-angle nonprecision approaches and adherence to published minimum safe altitudes. “Other actions included a review of the training in support of nonprecision approaches and the provision of additional information relating to the use of the aircraft’s autopilot/flight director system,” the report said.
Sickened by Mysterious Odor
Airbus A321-131. No damage. No injuries.
The A321 was descending through 12,000 ft to land at London Heathrow Airport the morning of Oct. 21, 2012, when the flight crew detected a strong odor causing throat and eye irritation. The copilot soon became dizzy and nauseous.
“The commander used the interphone to call the purser, who confirmed that there was also an odour in the cabin and that she was experiencing the same symptoms as the copilot,” said the report by the U.K. Air Accidents Investigation Branch (AAIB).
Both pilots donned their oxygen masks, and a request was made to air traffic control (ATC) for priority landing clearance. “After an uneventful approach, the aircraft landed within 10–15 minutes of the onset of the smell,” the report said. “The aircraft was halted on a parallel taxiway, and the engines and air conditioning were shut down. … After shutting the engines down, the situation in the cabin improved, although a few [of the 139] passengers reported light throat irritation.”
However, the copilot’s dizziness and nausea persisted, and several other crewmembers continued to experience eye and throat irritation. “As a result, the entire crew were sent to a local hospital for examination,” the report said. “They were released after several hours, by which time their condition had improved and the results of blood tests, taken earlier, produced no medical findings.”
An examination of the A321’s engines, air conditioning system, galleys and lavatory revealed nothing to explain the odor or the illness it had caused. After the recirculation and avionics filters were replaced, the aircraft was released for a ferry flight to its home base in Frankfurt, Germany. The crew received medical examinations in a Frankfurt hospital, with no abnormal results. A further examination of the aircraft revealed nothing about the source of the odor.
“This event thus joins a growing number of cases in which there has been a similar lack of conclusive evidence as to the cause(s) of aircraft cabin air quality issues,” the report said.
Although research has shown that cabin air can be contaminated by the pyrolysis (thermochemical decomposition) of engine and auxiliary power unit lubricants, “in tests where measurements of contaminants have been taken, the concentration is invariably well below internationally agreed levels for occupational exposure,” the report said.
Oxidized Brakes Overheat
Embraer 145. Minor damage. No injuries.
After touching down at Chicago (Illinois, U.S.) O’Hare International Airport the morning of June 3, 2011, the flight crew experienced the sensation that one brake pedal had fully released momentarily. An airport traffic controller saw a puff of smoke emerge from the main landing gear and asked the crew if a tire had burst.
Directional control was maintained during the landing roll, and the crew taxied the EMB-145 to a holding pad. “Braking action diminished as the taxi progressed,” said the report by the U.S. National Transportation Safety Board (NTSB). “When stopped on the pad, it was discovered that the emergency brake would not hold the aircraft stationary.”
In addition, the crew received messages warning of brake hydraulic system failure, as well as a report by a flight attendant that smoke was seen on the right side of the aircraft. The crew shut down the engines and started the auxiliary power unit. After an examination by aircraft rescue and fire fighting personnel, the aircraft was towed to a gate, where the 49 passengers deplaned.
Maintenance personnel found that a brake pressure plate and rotor had failed. “Separated brake parts were also found on the landing runway,” the report said. “Further examination of the incident brake and four other brakes revealed that they all contained varying levels of oxidation development.”
The report concluded that the oxidation that had caused the brake rotor to overheat and fail had not been detected by the operator’s maintenance personnel.
Investigators found that the operator had received details of a maintenance procedure developed by the brake manufacturer that involved the use of a fingernail or plastic tool to check brake rotors for oxidation. “The operator developed and provided related training to its maintenance personnel based on the manufacturer’s procedures,” the report said. “However, interviews with airline and contract maintenance personnel revealed that they were not familiar with the inspection and were not issued the plastic tool.
“Subsequently, the brake manufacturer and operator provided additional related training to the operator’s maintenance personnel, and the operator stocked their maintenance system with the specified tool.”
Control Lost in Wind Shear
Learjet 35. Substantial damage. No injuries.
As the Learjet neared Opa-Locka (Florida, U.S.) Executive Airport the afternoon of July 12, 2011, the automatic terminal information service broadcast indicated that visual meteorological conditions prevailed at the field, with surface winds from 340 degrees at 4 kt. The flight crew prepared for a visual approach to Runway 12.
At the time, terminal doppler weather radar data indicated strong convective activity northwest of the airport. “The data also identified possible microbursts and diverging winds near the surface,” the NTSB report said.
As the crew conducted the visual approach, the tower controller made several announcements about an area of weather about 5 mi (8 km) wide with light-to-moderate precipitation that had moved onto the airport. A special weather observation indicated that the direction of the surface winds varied between northwest and northeast, and that the velocity had increased to 15 kt, with gusts to 20 kt.
The Learjet was about 30 ft above the runway when it encountered wind shear. It rolled left, and indicated airspeed decreased about 20 kt. “As the pilot attempted to regain control of the airplane, the right wing tip made contact with the runway surface,” the report said. After touchdown, the pilot applied differential engine power and aggressive flight control inputs to stay on the runway.
The airplane was substantially damaged, but none of the four occupants was injured. After taxiing to the ramp and shutting down the engines, the pilots found that the right wing tip tank had separated and “was hanging by the lower wing skin,” the report said.
‘Gusts Were Nasty’
ATR 72-212. Destroyed. No injuries.
The aircraft was on a scheduled flight with 21 passengers and four crewmembers from Manchester, England, to Shannon (Ireland) Airport, which had strong, gusty winds from the northwest, good visibility, a few clouds at 1,000 ft and a broken ceiling at 1,300 ft.
The flight crew was cleared to conduct the instrument landing system (ILS) approach to Runway 24, which was 3,199 m (10,496 ft) long. (Shannon’s secondary runway, 13-31, had recently been closed and converted to a taxiway.)
During the approach briefing, the commander, the pilot flying, said that she intended to add 15 kt to the normal approach speed and touch down at the end of the runway touchdown zone, to avoid mechanical turbulence created by a hangar near the runway threshold, said the report by the Irish Air Accident Investigation Unit (AAIU).
As the crew began the approach, the tower controller advised that “occasional moderate turbulence was observed and forecast in the touchdown zone of Runway 24.” The winds had been reported from 300 degrees at 20 kt, but during the approach, the velocity increased to 24 kt, with gusts to 32 kt. The controller also passed this information to the crew.
The commander told investigators that the “gusts were nasty” when she flared the ATR for landing. The aircraft touched down on the nose wheel, bounced and touched down again, harder. The crew initiated a go-around and requested vectors for another ILS approach to Runway 24.
“During this second approach, landing turbulence was again experienced,” the report said. “Following bounces, the aircraft pitched nose-down and contacted the runway heavily in a nose-down attitude. The nose gear collapsed, and the aircraft nose descended onto the runway. … There were no injuries, but the aircraft was deemed to be damaged beyond economical repair.”
AAIU concluded that the probable cause of the accident was “excessive approach speed and inadequate control of aircraft pitch during a crosswind landing in very blustery conditions.”
Although the commander had planned to conduct the approach at 107 kt, the indicated airspeeds on touchdown were 139 kt and 140 kt, respectively. “This was partly due to the pilot flying increasing torque after flaring and partly due to the prevailing gusty conditions,” the report said.
The copilot had made no airspeed callouts during either approach, and the commander had not requested them. “A lightly loaded aeroplane at [indicated airspeeds] well above [the calculated approach speed] does not tend to touch down after the flare,” the report said. “At such speeds, the aeroplane has to be flown onto the runway; then, it can tend to bounce due to excessive lift still being generated by the wings.”
Electrical System Fails
Beech B200 King Air. Substantial damage. No injuries.
The crew was returning to Cambridge (England) Airport after completing a communications-relay mission in support of the Olympic Games the afternoon of July 28, 2012. While conducting the “Descent” checklist, the copilot, the pilot flying from the left seat, noticed that the fuel gauges read zero. At the same time, ATC told the crew that Mode C transponder replies no longer were being received.
After the commander replied that they likely had an electrical system problem, ATC received no further radio transmissions from the aircraft. “Over the next two to three minutes, the pilots experienced a progressive failure of all of the electrical equipment, with the exception of the left instrument panel electronic flight information system display,” the AAIB report said. “This remained powered by a backup power supply.” Other components, including the standby compass, also remained operational.
The report said that there was no checklist for a total electrical system failure. Among their troubleshooting actions, the pilots selected the alternate inverter and turned the battery switch and both generator switches off and on. However, they later told investigators that they did not place the generator switches in the “RESET” position.
The crew adhered to established communications-failure procedures and circled Cambridge Airport while attempting to manually extend the landing gear. The report noted that the captain neglected to pull the landing gear relay circuit breaker, as required, and that the copilot stopped operating the alternate gear-extension handle after feeling resistance to its movement.
The crew then conducted a no-flap landing. “The aircraft touched down gently at approximately 100 kt,” the report said. “Almost immediately after touchdown, the landing gear started to collapse.” The commander shut down the engines and feathered the propellers as the aircraft settled onto its belly cargo pod and main landing gear doors. The pilots and the two technical crewmembers evacuated without injury after the King Air came to a stop on the runway.
“It was not possible to determine the cause of the electrical failure,” the report said. “Although, due to their proximity, it is possible that the ignition-and-engine-start switches could have been operated by mistake instead of the anti-ice switches. This action would have caused the generators to go off-line. … If the generators had gone off-line for some reason, resetting them might have restored electrical power.”
A possible explanation for the landing gear collapse was that “the crew ceased operating the alternate extension handle before the landing gear was fully extended,” the report said. “The electrical failure meant that the crew had no indication of the landing gear position and therefore could not confirm that the gear was down and locked prior to landing.”
Inadvertent Prop Overspeed
Bombardier DHC-8-315. No damage. No injuries.
The first officer, the pilot flying, had his hand on the power levers during a flight idle descent to land at Weipa, Queensland, Australia, the night of Dec. 6, 2011. “When the aircraft encountered turbulence, the first officer inadvertently lifted one or both of the flight idle gate release triggers and moved the power levers below the flight idle gate,” the ATSB report said.
Both propellers exceeded the maximum limit by more than 300 rpm briefly before the first officer, hearing the beta warning horn and the increased propeller noise, moved the power levers back above the flight idle gates. “The propellers returned to the normal controlled operating rpm,” the report said.
The aircraft subsequently was landed without further incident in Weipa, where maintenance personnel found no damage to the engines or propellers.
Noting that many Dash 8-100, -200 and -300 series aircraft do not have a means to prevent inadvertent or intentional movement of the power levers below the flight idle gates in flight, the report said, “This design limitation has been associated with several safety occurrences.”
At the time of the incident, beta-lockout modifications had been mandated by aviation authorities in Papua New Guinea and the United States. Transport Canada subsequently announced its intention to issue an airworthiness directive requiring such modifications in all Dash 8-100, -200 and -300 aircraft.
Engine-Out Control Loss
Cessna 421C. Destroyed. Seven fatalities.
The 421 was en route at 21,000 ft from St. Louis, Missouri, U.S., to Destin, Florida, the afternoon of July 9, 2011, when the pilot declared an emergency due to a rough-running right engine and diverted the flight to Demopolis (Alabama) Municipal, an uncontrolled airport about 10 nm (19 km) away. A few minutes later, the pilot told ATC that he had shut down the right engine.
The airplane was at 17,000 ft when it reached the airport, and the pilot continued the descent while circling the field. “The airplane descended through 2,300 ft when it was abeam the runway threshold on the downwind leg of the traffic pattern,” the NTSB report said. ATC radar contact was lost when the airplane was at 700 ft (600 ft above ground level) and about 3 nm (6 km) from the approach end of Runway 22.
“The airplane was configured for a single-engine landing and was likely on or turning to the final approach course when it rolled and impacted trees,” the report said. “The airplane came to rest in a wooded area about 0.8 mi [1.3 km] north of the runway threshold, inverted, in a flat attitude. A majority of the airplane [was] consumed by a postcrash fire.” All seven occupants were killed.
Investigators determined that the right engine had failed because of a fatigue fracture of one of the teeth on the camshaft gear. “The remaining gear teeth were fractured in overstress and/or were crushed due to interference contact with the crankshaft gear,” the report said. “Spalling observed on an intact gear tooth suggested abnormal loading of the camshaft gear; however, the origin of the abnormal loading could not be determined.”
Distracted by Chatter
Beech 58 Baron. Substantial damage. No injuries.
The pilot was conducting the “Before Landing” checklist on approach to the airport in Sugar Loaf Mountain, Michigan, U.S., the afternoon of July 10, 2012, when he became distracted by a conversation between his two passengers.
“Earlier in the flight, the pilot briefed his passengers about having a sterile cockpit environment during the landing phase of flight, but the conversation did not cease,” the NTSB report said.
The pilot did not complete the checklist and neglected to extend the landing gear. He told investigators that he did not hear the gear-warning horn. “Before he realized that the gear was still up, the airplane impacted the runway, sustaining substantial damage to the fuselage during the wheels-up landing,” the report said.”
Mist Shrouds Unmarked Tower
Bell 206B. Destroyed. Two fatalities.
The pilot was repositioning the JetRanger from North Bay to Kapuskasing in Ontario the afternoon of July 23, 2010, in preparation for sightseeing flights the next day. Another company pilot was aboard as a passenger. The Transportation Safety Board of Canada (TSB) determined that the pilot’s preflight review of weather conditions had been inadequate and that he was not aware of deteriorating conditions along the route.
Data recovered from the global positioning system (GPS) receiver indicated that the helicopter was flown at progressively lower altitudes and that higher terrain was encountered as the visual flight rules flight progressed.
The helicopter was about 52 ft above the ground when it struck an unmarked and unlighted 79-ft radio tower located atop a hill and descended to the ground near Elk Lake about 72 minutes after departing from North Bay.
“Reduced visibility likely obscured the tower and reduced the available reaction time the pilot had to avoid the tower,” the TSB report said. “Because the tower was not depicted on the VNC [visual navigation chart] or GPS, the pilot was not likely aware that it existed.” The report noted that the GPS receiver’s database had not been updated.
|Preliminary Reports, May 2013|
|Date||Location||Aircraft Type||Aircraft Damage||Injuries|
|May 2||Catskill, New York, U.S.||Grumman G-44 Widgeon||substantial||1 fatal|
|Witnesses saw the seaplane maneuvering low over the Hudson River before it struck the water and sank.|
|May 3||Chorgolu, Kyrgyzstan||Boeing KC-135R Stratotanker||destroyed||3 fatal|
|The airplane, operated by the U.S. Air Force, struck mountainous terrain during a local flight from Bishkek-Manas International Airport.|
|May 4||Newtok, Alaska, U.S.||Cessna 207A||substantial||4 minor|
|The airplane was on a scheduled passenger flight when it crashed about a mile from the airport during a visual approach in fog.|
|May 5||Valencia, Venezuela||Learjet 60||destroyed||2 fatal|
|Instrument meteorological conditions prevailed when the Learjet crashed in a residential area about 3 km (2 nm) from the runway during final approach. A building and six vehicles were damaged, but no one on the ground was injured.|
|May 7||La Junta, Colorado, U.S.||Bell 206L-1||substantial||3 none|
|The helicopter struck terrain after tail rotor control was lost during an aerial observation flight.|
|May 8||Wamena, Indonesia||British Aerospace 146-200QT||destroyed||1 serious|
|Oil barrels were being unloaded with a forklift when a fire erupted and engulfed the aircraft.|
|May 8||Honolulu, Hawaii, U.S.||Robinson R22 Beta||substantial||1 minor, 1 none|
|The engine lost power during an aerial photography flight. The helicopter skidded into a parked vehicle during the subsequent autorotative landing on a road.|
|May 13||McMinnville, Oregon, U.S.||Learjet 35A||substantial||3 none|
|The Learjet overran the runway after the thrust reversers and the wheel brakes malfunctioned on landing during a postmaintenance repositioning flight. The squat switches on both main landing gear were found loose.|
|May 16||Shenyang, China||Harbin Yunshuji Y-12||destroyed||1 serious, 2 minor|
|The aircraft crashed on a road shortly after taking off for a cloud-seeding flight.|
|May 16||Mon Hsat, Myanmar||Xian MA60||substantial||2 serious, 53 minor/none|
|The left main landing gear collapsed after the aircraft overran the runway on landing.|
|May 16||Jomsom, Nepal||de Havilland Twin Otter||destroyed||6 serious, 15 minor|
|The Twin Otter veered off the runway on landing, traveled down an embankment and came to a stop on a river bank.|
|May 16||Floriston, California, U.S.||Cessna 421C||destroyed||1 fatal|
|While descending in visual meteorological conditions (VMC) to land in Reno, Nevada, the pilot reported that the airplane was in a spin. The 421 then struck mountainous terrain.|
|May 23||Krakow, Poland||Piper Seneca||destroyed||3 fatal|
|VMC prevailed when the Seneca struck a mountain at 5,600 ft during a personal flight from Poznan, Poland, to Bratislava, Slovakia.|
|May 24||London, England||Airbus A319-131||NA||80 none|
|The A319 was departing from London Heathrow Airport when the fan cowl doors on both engines separated, damaging the airframe and causing fuel and hydraulic leaks. The crew shut down the right engine due to a fire while returning to land at Heathrow.|
|May 24||Jalal-Abad, Kyrgyzstan||Antonov 2R||destroyed||3 fatal|
|The aircraft crashed under unknown circumstances during a fumigation flight to combat locusts.|
|May 24||Johnstown, New York, U.S.||Piper Seneca II||destroyed||3 fatal|
|The airplane was on a volunteer medical transport flight from Boston to New York when it entered an uncontrolled descent, broke up in flight and crashed in a reservoir.|
|May 26||Port-au-Prince, Haiti||Boeing KC-137E||substantial||143 none|
|The transport, operated by the Brazilian air force, veered off the runway during a rejected takeoff due to an engine fire.|
|May 27||Eisenach, Germany||Piper Twin Comanche||destroyed||1 fatal|
|The aircraft crashed out of control shortly after takeoff.|
|May 27||Simikot, Nepal||Cessna 208B Caravan||substantial||11 none|
|The Caravan veered off the runway and struck a ditch after the right tire burst on landing.|
|May 31||Wamena, Indonesia||British Aerospace ATP||substantial||3 none|
|The nose landing gear collapsed when the cargo aircraft veered off the runway on landing.|
|NA = not available
This information, gathered from various government and media sources, is subject to change as the investigations of the accidents and incidents are completed.