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.
Airbus A319. Damage, injuries not reported.
The A319 flight crew “did not pay enough attention to the complex weather condition” and exercised “weak” decision making when they pressed ahead with an approach into known severe thunderstorm activity after several other crews had diverted to alternate airports, said the Civil Aviation Administration of China (CAAC).
The aircraft was upset by wind shear-related turbulence associated with a suspected microburst and stalled during an instrument landing system (ILS) approach to Wuxi, China, the morning of Sept. 14, 2010. A recently published English translation of the CAAC’s final report on the serious flight incident said that the A319’s electronic flight control system (EFCS) “saved the plane from the stall condition.” After regaining control of the aircraft, the crew diverted to another airport.
The aircraft had departed from Chongqing at 0745 local time. About an hour later, the crew received a special report from the airline’s dispatch office about severe thunderstorm activity at the Wuxi airport. The Airbus was about 30 minutes from Wuxi at 0900 when an airport traffic controller advised the crew to expect the ILS approach to Runway 03 and that surface winds were from 040 degrees at 11 kph (6 kt) and visibility was 2,400 m (1.5 mi) in a “light thunderstorm” and light fog. However, “strong lightning” was observed west of the field.
Subsequent updates indicated that the weather conditions deteriorated rapidly as the thunderstorm producing the strong lightning moved over the airport. The controller advised the crew that the terminal area was “covered by thunderstorm” and that “some planes ahead of you diverted to Nanjing.” Nevertheless, the crew requested and received radar vectors to intercept the ILS localizer at 2,140 ft.
The A319 encountered severe turbulence as it descended through 1,680 ft. “Under the influence of microburst and the following wind shear, the aircraft attitude changed significantly,” the report said. The aircraft encountered a strong downdraft, and the autopilot continuously increased angle-of-attack (AOA) to keep the A319 on the glideslope.
Indicated airspeed decreased below the selected 126 kt. A “LOW ENERGY” warning activated, and the crew reacted by changing the selected airspeed to 131 kt, rather than manually applying full power as required by standard operating procedure.
The change in the selected airspeed resulted in a slow increase in thrust. Meanwhile, the aircraft’s AOA continued to increase, causing airspeed to decrease at a rate of 7 kt per second. When AOA neared the stall value, the EFCS “alpha protection” mode activated; it disengaged the autopilot, applied maximum thrust and trimmed the tail control surfaces to reduce the AOA, which was nearing 23 degrees.
The report indicates that the EFCS was nearly overwhelmed by the forces imposed on the aircraft by the thunderstorm. Despite the application of maximum thrust and nose-down pitch, the A319 stalled, rolled right and began to sink at 3,924 fpm. The EFCS kept the bank angle from exceeding 44 degrees and eventually recovered the aircraft from the stall at about 884 ft. The crew conducted a go-around and landed the aircraft at Ningbo about 30 minutes later.
The English translation of the CAAC report did not specify how many people were aboard the A319 or whether there were any injuries or damage during the thunderstorm encounter. The report indicated that the aircraft was inspected at Ningbo and subsequently released for service.
Based on the findings of the investigation, the CAAC recommended that airlines “strengthen training on safety awareness and skills, preventing flight crews from reckless flight in severe weather conditions.”
Ice Blocks Windshield
Learjet 35A. Minor damage. No injuries.
The first officer was the pilot flying during a medevac flight conducted in instrument meteorological conditions from Kenai, Alaska, U.S., to Ted Stevens Anchorage International Airport the night of March 5, 2012. The bleed air windshield-deicing system was engaged, but the first officer found that her windshield was covered with ice after the Learjet descended below the clouds during a global positioning system (GPS) approach.
“Although the captain’s windscreen was partially covered with ice, he could still see the runway, so he took control of the airplane and continued the approach,” said the report by the U.S. National Transportation Safety Board (NTSB).
The captain confirmed that the windshield bleed air deicing system was engaged and also activated the alcohol windshield-deicing system. Nevertheless, his windshield abruptly iced over as the Learjet touched down on the runway.
“Unable to see the runway ahead and with limited visibility to each side, the flight crew attempted to activate the engine thrust reversers to slow the landing roll, but the airplane subsequently veered to the right of the runway centerline, and the right wing collided with a snow berm,” the report said. The Learjet then veered off the right side of the runway and came to a stop embedded in a snowbank. Damage was minor, and none of the six people aboard was hurt.
Investigators determined that the airplane had encountered severe icing conditions that exceeded the capabilities of its ice-protection systems.
The report noted that 15 minutes prior to the incident, an airport traffic controller at nearby Elmendorf Air Force Base had advised the approach control facility, which is shared by the base and the international airport, that the pilot of a General Dynamics F-16 had conducted a go-around due to severe icing of his canopy on approach.
There was no record that this pilot report of severe icing was relayed to the pilots of the Learjet or another airplane operating near the international airport. The report said that the approach controller’s failure to relay the report to the Learjet crew was a contributing factor in the incident.
Runaway Baggage Tug
Boeing 737-300. Substantial damage. No injuries.
The operator of a baggage-cart tug stopped on the ramp at Los Angeles International Airport to pick up two bags the night of April 9, 2010. “He exited the tug without setting its parking brake, turning off its engine or placing the gear selector in neutral or park, which was not in accordance with the tug company’s ground equipment general driving rules,” the NTSB report said.
The tug operator placed one bag on the tug’s passenger seat, which also was against the rules. While he was handling the other bag, the bag that had been placed on the passenger seat fell off the seat, onto the accelerator pedal.
The unoccupied tug moved forward about 30 ft (9 m), struck a hydrant fuel cart and continued toward a 737 about 130 ft (40 m) away. The airplane was being pushed back from a gate for a departure with 109 people aboard. The tug operator ran after the tug, boarded it and tried to apply the brakes, but jumped clear as the tug neared the 737.
The tug struck the airplane’s left engine and lower fuselage, and came to a stop after striking the right engine. Damage was substantial, but there were no injuries.
The report noted that the tug has a backup system activated by a switch below the operator’s seat that disengages the engine, if necessary, when the operator leaves the seat. Investigators found that this backup system was inoperative.
Brakes Overheat During Taxi
Shorts 360. Substantial damage. No injuries.
The cargo airplane was about 60 lb (27 kg) over the certified maximum weight for takeoff from Houston the morning of May 17, 2012. The flight crew decided to reduce the takeoff weight by using higher-than-normal power settings to consume fuel and to use the wheel brakes to control the freighter’s speed during the long taxi to the departure runway, the NTSB report said.
While the 360 was being taxied to the runway, the fusible plugs in the wheels on both main landing gear melted, causing the tires to deflate, as designed, when the wheels overheated. The pilots felt the airplane yaw at the same time they received a radio message that the right wheel was on fire. They shut down the airplane on the taxiway and attempted to put out the fire with handheld extinguishers. The fire eventually was extinguished by airport firefighting personnel, using foam suppressant.
“The fire caused severe damage to the right main gear housing, which was part of the stub wing assembly structure and incorporates the attachment fitting for the wing strut,” the report said. “The operator’s maintenance department believed that the fire caused substantial structural damage to the extent that repair was not practical.”
The operator told investigators that the pilots had been trained not to “ride the brakes” while taxiing. “The captain stated that he did not realize that he was in danger of blowing the tires, much less causing a fire; otherwise, he would not have attempted to burn off excess fuel while taxiing,” the report said.
‘Fixation’ Leads to Flameout
Pilatus Turbo Porter. Substantial damage. Two fatalities.
The aircraft had sufficient fuel for seven hours of flight when it departed from Balikpapan, Indonesia, with the pilot and a passenger aboard for a six-hour aerial survey flight the afternoon of April 25, 2012. About 4.5 hours later, the passenger sent a text message to his employer, stating: “Run out of fuel, landing on road.”
The wreckage was found the next day on a slope near a mining road. The Turbo Porter had been in a descending right turn toward the road when it crashed, and both occupants had been killed. Examination of the aircraft showed that the engine had flamed out and the propeller had been feathered, with no sign of rotation on impact, said the report by the National Transportation Safety Committee of Indonesia.
“Both of the main fuel tanks were empty, with no evidence of fuel leak and smell at the site,” the report said.
The two main tanks are in the wings and hold 170 gal (643 L) of fuel. The aircraft also had two auxiliary tanks mounted on pylons beneath the wings. The auxiliary tanks hold 126 gal (477 L) of fuel, which is transferred to the main tanks by manually activated electric pumps.
“The transfer of fuel from the underwing auxiliary tanks to the main tanks should be performed when the main tanks are less than three-quarters but not less than half full,” the report said.
The pilot, who had fewer than 100 flight hours in type and was conducting only his third survey flight, likely was experiencing an elevated level of stress exacerbated by the “highly demanding survey operator,” the report said.
Noting that aerial surveys typically are flown between 1,500 and 2,500 ft above the ground, the report said, “The pilot likely fixated on the survey-flight execution and lost awareness of his fuel situation. The transfer of fuel from the auxiliary tanks was not performed during the flight, as required.”
Propeller Blade Fractures
ATR 72. Substantial damage. No injuries.
The aircraft was departing from Taipei, Taiwan, for a scheduled flight with 72 passengers and four crewmembers the evening of May 2, 2012, when the left engine fire-warning light illuminated. The flight crew requested radar vectors from ATC to return to the airport.
The report by the Aviation Safety Council of Taiwan (ASC) indicated that the crew had some difficulty while returning to the airport. The aircraft deviated from assigned headings, and the crew received several enhanced ground-proximity warning system (EGPWS) warnings and then several stall warnings while climbing. The crew subsequently was able to complete an ILS approach and land the aircraft without further incident.
Investigators found that an oil-scavenge pipe on the left engine had been damaged by debris from a fractured propeller blade and had leaked oil onto an exhaust pipe, causing the fire. ASC determined that the propeller blade fracture had resulted from a molding defect introduced during the manufacture of the blade.
Porous Fuel Caps
Beech 58 Baron. Substantial damage. One fatality.
Investigators determined that the left engine lost power shortly after the Baron departed from a private airstrip in Calhoun, Kentucky, U.S., the afternoon of April 1, 2012, to refuel at a nearby airport. The airplane rolled left and struck wooded terrain in an inverted attitude, killing the pilot.
Tests of the engines revealed no mechanical discrepancies. However, examination of the fuel system showed signs of “long-term water contamination,” the NTSB report said. The condition of the outer O-rings on both fuel caps had deteriorated. Rust-colored water was found in various fuel system components, and the lines to the fuel system drains were blocked by rust particles.
NTSB concluded that the probable cause of the accident was “the failure of the pilot to maintain airplane control after experiencing a loss of power from the left engine due to water contamination of the fuel system.” The pilot’s inadequate preflight inspection of the airplane and an inadequate annual inspection five months before the accident were contributing factors.
The report noted that Beech Aircraft had revised the maintenance manuals for some 55- and 58-series Barons to require periodic fuel-cap overhauls. This action followed the findings of an investigation of an accident involving fuel contamination that occurred in Canada in September 2008. However, the serial number of the Baron that crashed in Calhoun was not included among those requiring fuel-cap overhauls.
“Since this accident, the manufacturer has revised its Beech 55 and 58 maintenance manuals to include the fuel cap overhaul requirement for all potentially affected airplanes,” the report said.
Faulty Fuel Gauge
Aero Commander 500B. Substantial damage. Two minor injuries.
Before taking off from Broomfield, Colorado, U.S., the afternoon of March 1, 2013, for a test flight following installation of a new left engine, the pilot checked the fuel gauge, which indicated 65 gal (246 L). “Due to the design of the fuel system, it is not possible to visually check the fuel level to confirm that the fuel gauge is accurate,” the NTSB report said.
Shortly after takeoff, the pilot was reducing power for the climb when the left engine surged and lost power. “He immediately turned left back toward the airport and contacted the control tower to advise that he was making a single-engine, straight-in approach to land,” the report said.
After the landing gear was extended, the right engine surged and lost power. The pilot declared an emergency, retracted the gear and landed the Aero Commander on a nearby golf-course fairway. The airplane’s fuselage, left wing and left-engine propeller blades were damaged during the forced landing, and both occupants sustained minor injuries.
Investigators determined that the loss of power had been caused by fuel exhaustion. “Post-accident application of battery power to the airplane confirmed that the fuel gauge indicated 65 gallons,” the report said. “However, when the airplane’s fuel system was drained, only about 1/2 gallon [2 L] of fuel was recovered.”
Inexperience Cited in Control Loss
Bell 206B JetRanger. Destroyed. One fatality, four minor injuries.
The JetRanger struck a steep slope near Loder Peak, Alberta, Canada, about 13 minutes after departing from Kananaskis for an aerial tour the morning of March 30, 2012. The four passengers sustained minor injuries, and the pilot died of head and neck injuries about five hours after the crash.
The pilot’s inexperience in mountain flying was a factor in the accident, according to the report by the Transportation Safety Board of Canada. He had no previous mountain-flying training or experience and had logged only 2.6 flight hours, in a Robinson R44, in the 21 months before being hired by the tour operator in February 2012.
“Based on the pilot’s self-reports of having approximately 500 hours of helicopter flight experience in British Columbia and no accidents, the company considered the pilot to have adequate knowledge, skill and experience to safely conduct mountain tour flights with minimal recurrent flight training and check-out,” the report said.
“The pilot had demonstrated a strong reluctance to fly in close proximity to mountain slopes during the [company] training flights,” the report said. However, after departing on the tour flight, he flew very close to mountainous terrain and “attempted to cross a mountain ridge at an altitude that did not provide safe terrain clearance.” A visual illusion associated with the absence of a horizon likely caused the pilot to make inappropriate control inputs while attempting to turn away from the slope.
“The helicopter either sustained a tail-rotor strike on terrain or, more likely, entered a condition of aerodynamic loss of tail-rotor effectiveness, resulting in an uncontrolled rotation, loss of control and collision with terrain,” the report said. The wreckage was found 600 ft (183 m) below the crest of a 7,300-ft (2,225-m) ridge.
Fueling Mat Neglected
Robinson R44. Substantial damage. No injuries.
A line technician neglected to remove a rubber mat from the fuselage after refueling the R44, and the pilot did not notice the mat before departing from Tulsa, Oklahoma, U.S., for a short business flight the night of Feb. 6, 2012.
The helicopter was climbing through 150 ft when the pilot heard a loud bang and lost control of the tail rotor. The fueling mat had been blown off the fuselage and had struck the tail rotor, resulting in the fracture of both tail rotor blades, the NTSB report said. The pilot subsequently conducted an autorotative landing on an airport ramp without further incident.