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 717-200. No damage. No injuries.
The flight crew had been cleared to conduct an instrument landing system approach to Runway 24 at Perth (Western Australia) Airport the morning of July 26, 2014. The automatic terminal information service indicated that visibility was 3 km (2 mi) in rain showers and that the ceiling was at 800 ft. Runway 21 and Runway 24 were in use, and both were reported as wet.
The aerodrome controller had just resumed his position after a 30-minute break when the first officer established radio communication with the airport control tower. The aerodrome controller acknowledged the 717 pilot’s call and then cleared the crew of an Airbus A330 to land on Runway 21.
About the same time, an airport safety officer drove a ground vehicle to a holding point near the approach threshold of Runway 24 to conduct a routine runway inspection. “The safety officer’s vehicle, call-sign ‘Safety Two,’ was bright yellow and fitted with a rotating orange beacon which was switched on,” said the report by the Australian Transport Safety Bureau (ATSB).
The safety officer advised the airport surface movement controller of his position and was cleared to enter Runway 24 and to hold short of Runway 21. The surface controller then wrote “S2” on the console runway strip to indicate that Runway 24 was occupied by the vehicle.
“At that time, NXL [VH-NXL, the 717’s registration number] was on final approach for Runway 24 about 7.5 nm [13.9 km] from the runway,” the report said. “Neither of the flight crew of NXL recalled hearing the vehicle being cleared onto the runway.”
After checking the Runway 24 precision approach path indicator (PAPI) for damage from an earlier rain squall, the safety officer drove the vehicle along the centerline of Runway 24, toward the intersection of Runway 21.
Meanwhile, the A330 crew landed on Runway 21 after having asked that the PAPI for that runway be set to maximum intensity. The aerodrome controller then cleared the crew of a Fokker 100 for takeoff from Runway 21.
“After observing that aircraft [the Fokker] pass through the intersection of Runway 24, the ADC [aerodrome controller] picked up the flight progress strip for NXL, scanned the runway but did not see the vehicle on it,” the report said. “The ADC then moved the strip into the console runway bay without noticing the safety vehicle strip while simultaneously observing the F100 become airborne.”
The ADC then cleared the 717 crew to land on Runway 24. The aircraft was 1,000 ft above the ground and 1.5 nm (2.8 km) from the runway threshold, and the safety vehicle was moving along the centerline, away from the threshold. The airport surface controller later told investigators that he heard NXL being cleared to land but assumed that it was landing on Runway 21.
The safety officer said that he did not hear the 717’s clearance to land on Runway 24 because his attention might have been diverted by “chit chat” on the company radio frequency.
“When cleared to land, NXL was still in cloud, and the first officer sighted the runway when at about 700 feet above the ground,” the report said. The 717, with 105 passengers and five crewmembers aboard, was touching down on the runway when the first officer saw the vehicle’s flashing lights and told the captain, “Go around, car on the runway.”
The captain initiated a go-around, and the aircraft lifted off the runway about six seconds later and about 740 m (2,428 ft) from the approach threshold. The captain later told investigators that it was a “split-second decision to go around” before thrust reverse was activated. He said that if they had activated the engine thrust reversers, they would have been committed to the landing.
At the time, the safety vehicle was 1,180 m (3,871 ft) from the runway approach threshold and facing away from the aircraft. “The [safety officer] did not see the aircraft until it passed about 150 feet over the vehicle,” the report said.
The ATSB concluded that there were two possible reasons the aerodrome controller did not see the vehicle’s runway progress strip when he moved the 717’s flight progress strip into the console bay: “The process of placing the aircraft strip without reconciling with the vehicle strip already there was a muscle memory or automatic process rather than a conscious one; or, the combination of picking up the strip, talking and scanning all at once when issuing a landing clearance meant that the controller was looking outside at the runway, talking and moving the strip without looking at the bay to reconcile the strips.”
Bombardier CRJ200, Airbus A320. No damage. No injuries.
Visual meteorological conditions (VMC) prevailed when the flight crew of the CRJ, with 27 passengers and three crewmembers aboard, conducted a visual approach to Runway 26 at Port Elizabeth (South Africa) Airport the morning of July 20, 2014. The crew reported on a “long final,” and the airport traffic controller told them to “continue approach, landing assured.”
The controller then cleared the crew of an A320, which was holding short of the runway with 133 passengers and seven crewmembers aboard, for an “immediate” takeoff with “no stopping on the runway,” said the report by the South African Civil Aviation Authority.
The CRJ was about 2 nm (3.7 km) from the runway when the pilots saw the Airbus on the runway. “The crew of the [CRJ] elected to do a go-around due to insufficient separation between them and the departing aircraft,” the report said. “This decision was followed almost immediately by an instruction by the controller to go around.”
The pilots of both aircraft received, and complied with, traffic-alert and collision avoidance system (TCAS) resolution advisories. The CRJ pilots conducted a right climbing turn, and the A320 crew turned 30 degrees left.
Recorded air traffic control (ATC) radar data showed that the aircraft passed within 263 ft (80 m) vertically and 1,214 ft (370 m) horizontally. The CRJ subsequently was landed on Runway 26, and the A320 continued its scheduled flight without further incident.
The report said that the airport traffic controller’s workload was high at the time. He was instructing a student controller while handling two arrivals, two departures and a flight-calibration aircraft that was holding south of the airport. He also was preparing for a runway change due to a shift in wind direction.
“He became preoccupied (diverted attention) and most probably did not monitor the aircraft on final approach effectively, resulting in a loss in separation between the approaching and the departing aircraft,” the report said.
Shop Rag Snags Trim Cable
Boeing 737-800. Minor damage. No injuries.
A maintenance engineer conducting a routine visual inspection of the 737’s forward electronics and equipment compartment in Auckland, New Zealand, the night of June 7, 2013, found metal filings near the stabilizer trim system’s cable drum.
Further examination revealed that a shop rag had become trapped between the coils of the stainless steel trim cable and the cable drum. “The rag was causing the steel cable to bulge out from the drum and make contact with the aluminium spacer on the cable guide as the cable drum rotated,” said the report by the New Zealand Transport Accident Investigation Commission (TAIC).
The metal filings were from the aluminum spacer, which was worn through in places. The steel trim cable also had begun to wear.
Investigators determined that the shop rag had either been dropped or left behind during cleaning of the electronics and equipment compartment or the forward cockpit and subsequently had been drawn under the cable windings.
The report cited a similar incident in which a shop rag had become wrapped around the right main landing gear uplock assembly of another 737, causing momentary difficulty in retracting the landing gear during a departure from Melbourne, Australia, on Sept. 22, 2013.
The TAIC said that the key lesson from the incidents is that “all personnel must take care not to leave anything behind inside an aircraft after completing maintenance or cleaning tasks, especially in areas or near systems critical to flight safety.”
Prop Detaches From Hub
CASA 212-200. Substantial damage. No injuries.
The flight crew saw something move forward and away from the aircraft as it was climbing through 6,000 ft while departing from Ternate, Indonesia, for a scheduled passenger flight the afternoon of May 10, 2013. The pilot-in-command corrected for an asymmetric yaw and saw that the left propeller had separated from the engine.
“The pilots shut down the left engine by closing the fuel shut-off valve,” said the report by the Indonesian National Transportation Safety Committee. “The aircraft returned to Ternate and landed safely.” None of the 20 occupants was injured.
Investigators determined that the propeller hub had failed due to fatigue cracks that had developed in a large area of the hub. The report noted that, due to errors by the aircraft operator in data recording and analysis, the aircraft had exceeded by 154 cycles a scheduled inspection of the propeller assemblies; the inspection is required every 300 cycles.
Autopilot Disconnect Suspected
Piper Cheyenne. Destroyed. Two fatalities.
The Cheyenne was in cruise flight at 24,000 ft in VMC the morning of Dec. 15, 2012, when the pilot told ATC that he would “like to leave the frequency for a couple of minutes.” The controller approved the request but received no further radio transmissions from the pilot.
“About 20 seconds after the last transmission, the airplane banked to the right, continued in a spiral while rapidly descending and subsequently broke apart,” said the report by the U.S. National Transportation Safety Board (NTSB). “Portions of the wings, along with the horizontal stabilizers and elevators, separated during the breakup sequence.”
Examination of the wreckage, which was found in a canyon near Ely, Nevada, U.S., revealed no “mechanical malfunctions or failures that would have precluded normal operation,” the report said. “It is likely that the reason the pilot requested [permission] to ‘leave the frequency’ was to leave his seat and attend to something in the airplane. While leaving his seat, it is plausible [that] he inadvertently disconnected the autopilot and was unable to recover by the time he realized the deviation had occurred.”
Aluminum Bracket Fails
Beech King Air C90A. Substantial damage. No injuries.
The flight crew was preparing to land at Blacksburg, Virginia, U.S., the morning of Nov. 20, 2012, when they received an indication that the right main landing gear was not down and locked.
“The flight crew made multiple attempts to get a down-and-locked indication without success, so the pilot decided to abort the landing and divert to another airport with longer runways,” the NTSB report said.
On approach to the alternate airport in Roanoke, Virginia, the pilots again conducted the emergency landing gear extension checklist and then made a low pass near the airport control tower. A controller told the crew that all three landing gear appeared to be down.
“During the landing, the touchdown was normal, and the airplane slowed normally,” the report said. “However, as the airplane exited the runway, the right main landing gear collapsed. Examination of the wreckage revealed that the right wing, right nacelle and right wheel well had received substantial damage and that the right main landing gear, after collapsing, had punctured the right nacelle fuel tank.”
The pilots and their two charter passengers were not injured.
The failure of the right main landing gear was traced to an aluminum bearing actuator support bracket that had fractured and separated from its mounting position. The report noted that Beech Aircraft in December 2003 had issued a mandatory service bulletin calling for the replacement of aluminum brackets with steel brackets “no later than the next scheduled inspection, the next 200 flight hours or 24 months.” The manufacturer had requested that the U.S. Federal Aviation Administration (FAA) issue an airworthiness directive (AD) requiring compliance with the bulletin.
“Review of the airplane’s maintenance records confirmed that the airplane owner and the operator had not had the new steel brackets installed,” the report said. “Further, the FAA has not issued an AD for the main landing gear bearing actuator support brackets.”
Switch Mis-Selection Suspected
Piper Seneca 1. Destroyed. One fatality.
Witnesses heard unusual engine sounds as the Seneca took off from Broome, Western Australia, for a cargo flight to Port Hedland on July 11, 2012. The takeoff was conducted on a dark night toward open water.
“Other witnesses closer to the accident site reported hearing the engine sound suddenly cut out before the aircraft banked left and descended steeply towards the ground,” the ATSB report said. The pilot was killed when the Seneca struck sand dunes about 880 m (2,887 ft) from the runway.
Witness reports and recovered global positioning system (GPS) data indicated a significant reduction of engine power and groundspeed shortly after liftoff. The aircraft climbed for about 23 seconds before descending out of control.
The ATSB was unable to determine conclusively the probable causes for the loss of power from one or both engines, or for the pilot’s loss of aircraft control. “A reduction in engine noise at about the time the aircraft departed controlled flight could be consistent with both engines being inoperative, an attempt by the pilot to confirm an inoperative engine as part of his pre-feathering troubleshooting procedure or a pilot-initiated reduction in engine power in response to a loss of directional control,” the report said.
The report discussed the possibility that the pilot inadvertently turned off the left engine’s magnetos after retracting the landing gear on takeoff. Investigators found the magneto switches for the left engine in the “OFF” position during examination of the wreckage and subsequently learned that the guard cover for the switches was known to not fully close to protect the switches from inadvertent mis-selection.
“The proximity of the switches for the landing lights and auxiliary fuel pumps to the engines’ magnetos on the electrical switch panel increased the possibility of inadvertent switch operation,” the report said.
False Assumption About Fuel
Aero Commander 500S. Substantial damage. No injuries.
The pilot did not monitor the refueling of the Aero Commander or conduct a visual check of the fuel tanks before departing from Ely, Nevada, U.S., for a 4-hour 30-minute flight to coordinate aerial fire-suppression operations the afternoon of July 23, 2012.
“A design peculiarity of the fuel quantity system prevented in-cockpit determination of the actual fuel quantity once the fuel level rose above a value that was 21 gallons [79 liters] below the actual maximum capacity,” the NTSB report said.
The fuel gauges were on empty when the pilot turned back to base after flying for 4 hours and 15 minutes. “The fire [site] was located about 15 minutes (still air) flight time from the base airport, but the return flight would be subject to a headwind of about 10 knots,” the report said.
Shortly after turning back to base, both engines lost power due to fuel exhaustion. “Although the airplane was in the vicinity of a four-lane highway, the pilot opted to land on a two-lane highway due to significantly less vehicular traffic on that highway,” the report said. The Aero Commander’s wing tips were substantially damaged on contact with highway signs, but the pilot and his passenger (the mission coordinator) were not hurt.
Control Lost in Night IMC
Robinson R66. Destroyed. Five fatalities.
Shortly after departing from Endicott, New York, U.S., for a flight to Lehighton, Pennsylvania, the night of July 27, 2013, the pilot, who had a commercial license but no instrument rating, requested and obtained visual flight rules (VFR) flight-following service from ATC.
The NTSB report said that about 28 minutes later, while flying at 3,000 ft over a sparsely populated and heavily wooded area, the pilot radioed that the helicopter had inadvertently encountered instrument meteorological conditions (IMC) and asked, “Can you give us a heading to the nearest airport, please?”
The controller provided a vector to an airport about 8 nm (14.8 km) away, but the pilot did not immediately respond. The controller repeated the information shortly thereafter, and the pilot replied that he was “having trouble maintaining control here.”
The report said that although the pilot turned toward the airport, changes in the helicopter’s altitude and heading, and comments by the pilot were consistent with the known effects of spatial disorientation.
ATC radio and radar contact were lost shortly before the R66 descended into trees near Noxen, Pennsylvania. Investigators found no sign of a pre-impact mechanical failure or abnormality. The NTSB determined that the probable cause of the accident was “the pilot’s decision to continue VFR flight into night IMC, which resulted in spatial disorientation and a loss of control.”
Underestimated Hydraulic Leak
Bell UH-1H. Substantial damage. One fatality.
According to the helicopter operator’s director of maintenance, the pilot and a mechanic who worked on the helicopter were aware of a flight-control system hydraulic leak and had ordered replacement parts.
However, the hydraulic leak had not been fixed before the pilot departed from a staging area near Dove Creek, Colorado, U.S., to conduct a seismic survey flight the morning of July 16, 2013. The director of maintenance said that the pilot and the mechanic “did not expect the leak to cause a significant issue,” the NTSB report said.
The report said that loss of hydraulic fluid from a check valve fitting near the tail rotor servo likely resulted in very high collective control forces and pilot-induced flight oscillations as the helicopter neared the survey site.
The pilot overshot the survey site, and the external load, which was on a 50-ft (15-m) long line, struck the ground. The pilot released the external load, and the helicopter then banked steeply to the right and left before descending to the ground.
The NTSB concluded that the probable cause of the accident was “pilot-induced oscillations caused by the loss of hydraulic assist of the flight controls due to an excessive loss of hydraulic fluid during a critical phase of flight.” A contributing factor was “an inadequate analysis of the hydraulic leak by the pilot and mechanic.”