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.
Pitot Heat Ineffective
Airbus A321-231. No damage. No injuries.
Icing conditions that rendered the A321’s pitot heating system ineffective are believed to have caused serious fluctuations in indicated airspeed during two separate flights within a couple of months, said a report by the U.K. Air Accidents Investigation Branch (AAIB).
The first, and more serious, incident occurred the afternoon of April 20, 2012, as the aircraft neared London Heathrow Airport during a flight from Stockholm, Sweden, with 182 passengers and seven crewmembers. St. Elmo’s fire was visible, but the flight crew saw no sign of airframe icing as the aircraft descended in light turbulence to Flight Level (FL) 140 (approximately 14,000 ft). Total air temperature at the time was 3 degrees C (37 degrees F).
“Shortly after the aircraft entered cloud tops, there was a white flash of lightning, without any associated noise,” the report said. “Both pilots recalled that about one second after the flash [as the aircraft was descending through 14,800 ft], the airspeed indications on their primary flying displays (PFDs) fluctuated, with both the high- and the low-speed ends of the scale alternately visible.” The standby airspeed indicator also showed fluctuating airspeed indications, and there was a brief disruption of all three sources of altitude data.
“The pilots commenced the procedure for ‘Unreliable Speed Indication’ and turned off the flight directors,” the report said. The fluctuations lasted less than two minutes, but during that time, the master warning horn sounded, the autopilot disconnected and a traffic-alert and collision avoidance system (TCAS) resolution advisory (RA) was generated, calling for a descent. Shortly thereafter, a TCAS “clear of conflict” advisory sounded, and the crew leveled the aircraft at FL 140.
The crew received clearance from air traffic control (ATC) to enter a hold in visual meteorological conditions (VMC). The instrument fluctuations had stopped, and the pilots consulted the pitch-versus-power tables in the quick reference handbook (QRH) to confirm that the airspeed indications, all of which were showing 240 kt, were correct.
The electronic centralized aircraft monitor displayed an “AOA DISCREPANCY” message, indicating that the problem had been caused by a mismatch between the three angle-of-attack (AOA) probes, the report said.
“The crew discussed the implications of the failures and considered various scenarios, utilising the company’s decision-making tool, and decided to divert to London Stansted Airport, which was clear of adverse weather,” the report said. The subsequent landing was uneventful.
The pilots later told investigators that the company training they had received on unreliable airspeed indications had allowed them to handle the incident in a “straightforward” manner.
The second incident occurred on June 16, 2012, as the aircraft was climbing through 26,500 ft in VMC during a flight from Edinburgh, Scotland, to London Heathrow. As the A321 entered the top of what was described as a “dome of cloud,” the airspeed indications on both PFDs decreased to nearly zero twice before returning to normal.
“Disruption to the ASIs [airspeed indicators] ceased on or shortly after the aircraft left cloud,” the report said. The flight crew analyzed the situation and diverted the flight to London Stansted, where the winds were more favorable for landing.
The report said that the first incident occurred while the aircraft was being flown “within the boundary of current icing certification standards, which only consider supercooled water droplets.” The second incident occurred outside the icing-certification altitude/temperature envelope and may have involved an encounter with ice crystals.
Although a flash of lightning was seen shortly before the first incident began, there were no signs that lightning actually struck the aircraft. The erroneous TCAS RA was found to have been caused by the brief disruption of altitude data.
Noting previous events involving erroneous air data, including the accident involving Air France Flight 447, an A330 that stalled and descended into the Atlantic Ocean on June 1, 2009, the report said, “Airbus has conducted studies including investigating reported airspeed-indication problems, icing wind tunnel testing and instrumented flight tests, [and] is in the process of developing expanded envelopes for inclusion in the [icing certification] requirements.”
The report said that, meanwhile, the hazard of unreliable airspeed indications persists and that the A321 incidents discussed above “indicate that training to deal with unreliable air data can be effective.”
Entertainment System Ignites
Boeing 747-400. Minor damage. No injuries.
Inbound from Dallas, Texas, U.S., the 747 was about two hours from London Heathrow Airport the morning of Oct. 14, 2013, when the flight crew and some cabin crewmembers detected an “acrid, electrical burning smell,” said the AAIB report.
The engine indicating and crew alerting system then displayed a “SMOKE LAVATORY” message, indicating that smoke had been detected either in a lavatory or in the cooling duct for the in-flight entertainment (IFE) system.
The commander transferred control to the copilot and consulted the QRH while cabin crewmembers checked the lavatories and galley. Smoke and flames were found to be emerging from an IFE unit in Galley 4. The cabin crew used fire extinguishers, but the fire reignited repeatedly. The flames finally disappeared after five extinguishers were emptied.
The IFE unit was designed to self-extinguish after it was isolated from electrical power. “An internal investigation by the operator concluded that it was likely the [IFE unit] had remained powered during the incident, and this was the reason it continued to re-ignite,” the report said. Although a crewmember believed that he had isolated the IFE, investigators determined that he had completed only part of the isolation procedure.
Standing Water on Runway
Beech 400. Substantial damage. Three minor injuries.
A witness told investigators that there was a heavy downpour shortly before the Beechjet arrived at Macon (Georgia, U.S.) Downtown Airport the morning of Sept. 18, 2012. VMC prevailed, but the rainfall had left standing water on the ungrooved runways at the uncontrolled airport, said the report by the U.S. National Transportation Safety Board (NTSB).
The pilots chose to land on Runway 28, which was 4,694 ft (1,431 m) long, and calculated a reference landing speed (VREF) of 108 kt. The report said, however, that they likely did not consult the airplane’s performance charts, which showed that the required landing distances on a runway contaminated with standing water were 4,800 ft (1,463 m) at a VREF of 110 kt and 6,100 ft (1,859 m) at VREF plus 10 kt.
The copilot attempted to activate the airport’s lights, but the precision approach path indicator (PAPI) lights illuminated only briefly and could not be reactivated. Investigators later found that an open circuit breaker had prevented reactivation of the PAPI lights.
Analysis of recorded radar data indicated that the Beechjet crossed the runway threshold at about 125 to 129 kt and touched down within 1,000 ft (305 m) of the threshold. “Both crewmembers reported that although they used maximum thrust reverse, brakes and ground spoilers, they could feel a ‘pulsation’ in the brake system [and perceived] that the airplane hydroplaned,” the report said.
The airplane overran the wet runway onto a short grassy area, traveled down an embankment and across a highway, and came to a stop in a wooded area. The pilots and their passenger sustained minor injuries.
The investigation concluded that the flight crew “lacked a clear understanding of the actual wet-runway landing distance” and “exhibited poor crew resource management by not using the appropriate chart for the contaminated runway, not recognizing that the runway was too short based on the conditions … and not recognizing and addressing the excessive approach speed.”
Radio Volume Misset
Fairchild Metro, Bell 47G. No damage. No injuries.
A flight instructor and pilot aboard the helicopter were conducting closed-pattern work as the pilot of the Metro prepared to depart for a cargo flight from the uncontrolled airport in Ballina, New South Wales, Australia, the afternoon of Oct. 9, 2013.
The helicopter was landed about two-thirds of the way down Runway 06 and remained stationary while the instructor briefed the pilot for another circuit, said the report by the Australian Transport Safety Bureau.
The Metro pilot had seen the helicopter land and had broadcast on the common traffic advisory frequency (CTAF) that he was taxiing to Runway 06. The pilot made three more calls and, hearing no response on the CTAF, began the takeoff.
“Just prior to rotation, he sighted [the helicopter] stopped on the runway,” the report said. “He elected to continue the takeoff and increased the climb angle to provide separation with [the helicopter].”
The instructor aboard the helicopter told investigators that he had been making “appropriate calls” on the CTAF but had heard no calls from other pilots. After seeing the Metro pass overhead, he attempted to contact the Metro pilot on the CTAF but, after receiving no response, realized that the helicopter’s radio volume was set too low to hear other transmissions.
Faulty Contactor Drains Battery
De Havilland DHC-8-402. No damage. No injuries.
The Dash 8 was at 25,000 ft, en route with 20 passengers and four crewmembers from Edinburgh, Scotland, to Brussels, Belgium, the morning of Oct. 23, 2013, when the flight crew saw a “PUSHER SYSTEM FAIL” on the central warning panel (CWP). The flight crew conducted the appropriate QRH checklist and decided to continue to Brussels, the AAIB report said.
Shortly thereafter, a cabin crewmember told the pilots that the cabin lights were dimming. Eventually, all the lights extinguished, and several more cautions and warnings appeared on the CWP. As the flight crew consulted the QRH, the copilot’s electronic flight displays failed.
As electrical system failures continued to occur, the crew noticed that there was no load on the no. 2 generator. They declared an urgency and diverted to Manchester Airport, where the aircraft was landed safely.
“It is suspected that there had been a failure of the right starter/generator or its generator control unit and that a further latent failure of a contactor had prevented automatic connection of the right DC [direct current] bus to the left DC bus,” the report said. “The services normally powered by the right DC bus would now be powered by the main aircraft battery, which would progressively discharge.”
‘Improper Fuel Planning’
Beech King Air C90. Destroyed. Two fatalities.
The pilot was receiving ATC flight-following service during a visual flight rules (VFR) flight from Pine Bluff to Bentonville, both in Arkansas, U.S., the afternoon of Nov. 1, 2013. During descent, the pilot told ATC that he needed to divert to a closer airport because he was “low on fuel,” the NTSB report said.
Shortly thereafter, while diverting to Fayetteville, Arkansas, about 9 nm (17 km) away, the pilot said that he needed an even closer airport. The approach controller recommended Springdale, which was about 4 nm (7 km) away at his 12 o’clock position.
The pilot said that he had Springdale in sight, and the approach controller provided the airport traffic control tower frequency. When the pilot contacted the tower controller, he reported that he was low on fuel.
The tower controller issued wind conditions and the altimeter setting, and cleared the pilot to land on Runway 36. “Approximately 30 seconds later, the pilot advised that he was not going to make the airport,” the report said.
The pilot apparently attempted to land the King Air on a field. “Three witnesses reported seeing the airplane pull up abruptly and fall from about 300 feet to the ground in a right-wing-low, nose-low attitude,” the report said. Investigators determined that the airplane likely had stalled when the pilot attempted to avoid power lines crossing the field at 311 ft.
There was no sign of fuel spillage and no odor of fuel at the accident site. About 1.0 qt (0.9 L) of fuel remained in each fuel tank, but the fuel totalizer — a fuel quantity indicator that displays the total amount of fuel remaining in all of an aircraft’s fuel tanks — indicated that 123 gal (466 L) remained aboard the King Air.
“The pilot was likely relying on the fuel totalizer instead of the fuel gauges for fuel information,” the report said. “Information in the fuel totalizer is based on pilot inputs, and it is likely the pilot did not update the fuel totalizer properly before the accident flight.”
The NTSB concluded that fuel exhaustion leading to a total loss of power was the probable cause of the accident and that “improper fuel planning” and the “pilot’s reliance on the totalizer rather than the fuel quantity gauges” were contributing factors.
Descent Into the Sea
Piper Aztec. Substantial damage. Three fatalities, one serious injury.
The pilot departed with three passengers from Christiansted, on St. Croix, U.S. Virgin Islands, about 0445 local time the morning of Oct. 13, 2012, to deliver newspapers to Charlotte Amalie, on St. Thomas. Recorded radar data showed that the airplane initially was flown at 1,700 ft above the water before making a gradual descent to 200 ft.
“The airplane continued at 200 ft above the water for another 18 seconds before its radar target disappeared about 5 miles [8 km] from the destination airport,” the NTSB report said.
The surviving passenger told investigators that the pilot had flown progressively lower to “get under the weather.” She remembered seeing lights on the shoreline before the airplane “hit a wall” and filled with water. The pilot broke the left cockpit window and exited through it. The passenger also exited through the broken window.
“Examination of the wreckage revealed damage consistent with a high-speed, shallow-angle impact with the water,” the report said. The two rear-seat passengers were killed. The pilot also is believed to have been killed; his body had not been found when the report was published.
There was no record that the pilot obtained a preflight weather briefing. “Weather data and imagery were consistent with the passenger’s account of flying beneath the outer rain bands associated with a developing tropic storm southeast of the accident site,” the report said.
Heavy and Off-Balance
Britten-Norman Trislander. Minor damage. No injuries.
There were 11 passengers and a company employee aboard for a scenic flight from Pauanui Beach (New Zealand) Aerodrome the afternoon of Oct. 22, 2011. The pilot had conducted only one previous takeoff from the 782-m (2,566-ft) sand-and-grass runway, and that takeoff had been in a light airplane eight years earlier.
“The pilot did not check the expected aeroplane performance at Pauanui because, she said, the airline’s chief executive officer had told her that the runway was adequate for the expected takeoff weight of 4,080 kg [8,995 lb],” said the report by the New Zealand Transport Accident Investigation Commission (TAIC).
Witnesses said that the Trislander accelerated slowly, and the pilot perceived that airspeed “stagnated” at 60 kt. The airplane did not rotate when she pulled the control wheel fully aft. “The pilot then closed the throttles and braked hard,” the report said. “The aeroplane did not stop before the end of the runway and went through a low wooden rail marking the end of the runway.”
TAIC investigators found that neither the pilot nor the airline had performed weight-and-balance calculations before the flight. The actual takeoff weight was within limits, but the investigation concluded that the airplane was too heavy to provide adequate performance for a takeoff from the unimproved runway.
The report said that “the primary reason for the aeroplane’s failure to take off was that its centre of gravity was well forward of the maximum permissible limit,” which prevented rotation.
Robinson R66. Destroyed. One fatality.
The turbine helicopter was en route from Gillette, South Dakota, U.S., to Winner the morning of Oct. 1, 2011, when the main rotor mast separated 8 in (20 cm) below the teeter bolt. The R66 then struck terrain and burned near Philip, South Dakota.
“Examination of the mast revealed fracture features consistent with overload failure and mechanical damage indicative of mast bumping [contact between the rotor hub and rotor mast],” the NTSB report said. “The reason for the mast bumping event could not be determined due to the amount of thermal damage to the wreckage.”
‘Better to Continue’
Bell 206B. Substantial damage. One minor injury.
The JetRanger was in cruise flight at 2,000 ft near Shrewsbury, England, the afternoon of Oct. 4, 2013, when the pilot noticed that engine turbine temperature was near the maximum limit. He prepared to conduct a precautionary landing, but, as power was reduced during the approach, turbine temperature decreased.
Seeing no other abnormal engine indications, the pilot decided to continue to the destination, only a few miles away. “As the helicopter climbed away, the engine failed,” the AAIB report said. “The pilot carried out a forced landing, during which the tail boom struck the ground.
“He candidly commented that, on reflection, it would have been better to continue with the precautionary landing rather than having to attempt a forced landing without power from low altitude.”
Investigators determined that the engine likely failed due to oil starvation that caused a bearing to disintegrate. A foreign object, an O-ring, had entered the oil filter and lodged against a check valve that opens to provide oil to the bearings when the engine is running.
Bell 407. Substantial damage. Two fatalities, one serious injury.
Shortly after departing from Elmira, New York, U.S., for a VFR business flight to White Plains the night of Oct. 9, 2012, the helicopter encountered instrument meteorological conditions. The pilot, who held an instrument rating for airplanes but not for helicopters, decided to divert the flight to Mount Pocono, Pennsylvania.
Vertical visibility was estimated at 200 ft, and visibility was about 1/2 mi (800 m) in fog when witnesses saw the 407 flying very low over a highway in Coolbaugh Township, Pennsylvania. “Minimal ground lighting was present in the heavily wooded area surrounding the interstate,” the NTSB report said.
The helicopter was being flown at about 30 kt when it struck trees and crashed about 200 ft (61 m) off the shoulder of the highway. The pilot and one passenger were killed; another passenger sustained serious injuries.
The NTSB report concluded that the probable cause of the accident was “the pilot’s decision to continue VFR flight into instrument meteorological conditions due to self-imposed pressure to complete the trip