Blinded by a Light

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.

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Jets

Go-Around Conducted

Boeing 737-800. No damage. No injuries.

The 737, en route from Lille, France, with 160 passengers and six crewmembers the evening of Sept. 5, 2015, was on a nonprecision instrument approach to Porto, Portugal, when the commander was temporarily blinded by a laser light.

Night visual meteorological conditions (VMC), with surface winds variable at 2 kt, prevailed at the airport. The aircraft, of Irish registry, was turning onto final approach and descending to 3,000 ft, the minimum altitude at the initial approach fix for the VOR (VHF omnidirectional radio) approach to Runway 35, when the copilot, the pilot flying (PF), noticed a laser light emanating from the city center.

“The laser was not pointing directly at the aircraft and then disappeared from view, leading the PF to believe that it had been switched off,” said the report by Ireland’s Air Accident Investigation Unit (AAIU). “As it was quite a common occurrence to see laser activity at Porto, the PF did not mention it to the [commander].”

Shortly after the aircraft was established on the final approach course, the laser illuminated the cockpit. The copilot shielded his eyes with his left hand, and his vision was not affected by the laser light.

Seeing the copilot’s hand movement, the commander, who had been monitoring the flight instruments and was not aware of the laser light, looked up and sustained flash blindness, the report said.

Flash blindness is a “temporary visual loss or impairment during and following exposure to a light flash of extremely high intensity,” the report said. “The effects may last for several seconds to a few minutes.”

In this case, the commander told investigators that her eyesight returned to normal after a few seconds. She described the effect on her vision as the environment having become “completely white in front of me.” She said that she reported the laser light attack to the airport traffic controller after her vision cleared.

The laser light strike occurred just before the point at which the commander, as pilot monitoring, would have made a standard callout: “approaching descent.” Due to the copilot’s distraction by the light and the commander’s flash blindness, the callout was not made promptly and the associated actions were not performed.

“Consequently, the PF announced the ‘approaching descent’ call himself and carried out the actions associated with this call in order to set up the [autopilot and autothrottle control] modes required for the aircraft to perform the final approach,” the report said.

Because these actions had been delayed, the aircraft was slightly higher than appropriate for the approach. Airspeed and descent rate then increased as the desired flight profile was reacquired.

When the copilot called for extension of the landing gear and flaps to reduce airspeed, the commander realized that the approach had become unstable and called for a go-around.

The go-around was initiated at about 900 ft. The crew subsequently landed the aircraft without further incident on Runway 17.

“Data [indicate] that the majority (91 percent) of laser attacks on aircraft are from green lasers and that the attacks occur during night operations, when the aircraft are approaching an airport [and the] flight crew will have the cockpit lighting off or dimmed to allow the eye to become dark-adapted,” the report said.

As in the Porto incident, a laser attack can cause pilots to become distracted or suffer temporary flash blindness and lead to spatial disorientation and loss of situational awareness, the report said.

The AAIU noted that some countries have introduced legislation prohibiting the illumination of aircraft by lasers or other bright lights. “In Portugal, at present, it is not an offence to shine a laser light, or similar, at an aircraft,” the report said.

‘Action Slips’

Airbus A320, A319. No damage. No injuries.

Two incidents in which pilots inadvertently retracted the flaps instead of the landing gear on takeoff occurred the same day — Feb. 16, 2016 — at different airports in aircraft operated by the same airline.

The first incident involved an A320 making a morning takeoff from Amsterdam Schiphol Airport in the Netherlands with 167 passengers and six crewmembers aboard. When the copilot, the PF, asked the commander, the pilot monitoring (PM), to retract the landing gear, the commander moved the flap lever from position 1 (10 degrees extension) to position 0 (retracted) instead.

“The PM realised his error immediately, returned the lever to position 1 and told the PF what he had done,” said the report by the U.K. Air Accidents Investigation Branch (AAIB). “The PF reduced the nose attitude of the aircraft, maintained a positive rate of climb, and the airspeed did not decrease below VLS (the lowest selectable indicated airspeed).”

The report noted that the slats did not retract from their 18 degrees of extension in conjunction with the flaps, as designed, because the PM immediately returned the flap lever to position 1.

This event was classified as an incident; the AAIB identified the other event as a serious incident. It occurred at Bristol (England) Airport during an afternoon departure by an A319 with 125 passengers and six crewmembers aboard.

In this case, the PM (the copilot) and the commander did not immediately recognize that the flaps and slats, rather than the landing gear, had been retracted. Instead, the commander noticed that the VLS indication on his primary flight display was increasing rapidly. He lowered the aircraft’s pitch attitude and selected takeoff/go-around thrust.

The aircraft was 393 ft above the ground, descending at 1,300 fpm and 194 kt, when the ground-proximity warning system generated a “don’t sink, don’t sink” warning. Two seconds later, the A319 began to climb.

After both events, the aircraft were flown to their destinations without further incident.

“The operator classified the mis-selection of flap instead of landing gear as a type of ‘action slip’ where ‘an out-of-sequence step (the flap selection) was included in a series of routine, well-learnt behaviours (takeoff procedure),’” the report said.

Trim Disconnect

Cessna Citation 680. Minor damage. No injuries.

The flight crew departed from Wheeling, Illinois, U.S., to conduct an unspecified flight test the afternoon of Jan. 12, 2014. While climbing through 15,000 ft, the autopilot disengaged and an autopilot failure warning was generated. The crew decided to return to the airport.

“The pilot noted that while trying to slow the climb, extra force was required to push the airplane’s nose down,” said the report by the U.S. National Transportation Safety Board (NTSB). “He attempted to apply nose-down trim but felt no change.” The pilot noticed that the elevator was trimmed full-nose-up.

The crew subsequently landed the Citation without further incident. Examination of the airplane revealed that a connecting pin had dislodged, causing the left elevator trim driveshaft to disconnect from the trim actuator.

“The operator stated that it was aware that the elevator trim tab driveshaft pin on the same make and model airplane had dislodged on two previous occasions,” the report said. “The manufacturer is in the process of proposing changes to the drive pin dimensions and the method of securing the pin to prevent the elevator trim tab drive pin from dislodging.”

Misaligned Takeoff

Cessna CJ2. Substantial damage. No injuries.

Night VMC prevailed as the flight crew prepared to depart from Norwich, England, for a charter flight on Jan. 9, 2016. The commander said that he aligned the aircraft with white lights that he believed were the runway centerline lights before beginning the takeoff.

Shortly thereafter, the left main landing gear rolled onto wet grass, causing the aircraft to veer left, the AAIB report said. The commander attempted to regain directional control but rejected the takeoff after he realized what had happened.

The CJ2’s landing gear and fuselage were damaged during the excursion, but the three passengers and the pilots were not hurt.

Investigators determined that the crew had not followed the green turning-circle taxiways light and had inadvertently lined up with the runway’s left edge lights, rather than the centerline lights.

“Due to the extra pavement parallel to the runway, [the commander] did not realise he was lined up on the left edge prior to takeoff,” the report said. “The copilot commented that his attention may have been inside the cockpit too much during the line-up and setting of engine thrust. He added that, had he been more ‘heads up,’ he may have spotted the mistake.”

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Turboprops

Uncommanded Feathering

Beech 1900C. Destroyed. Four fatalities.

The flight crew was conducting a positioning flight from Miami (Florida, U.S.) Executive Airport the afternoon of Feb. 11, 2015. It was the airplane’s first flight following the replacement of the left propeller with an overhauled unit.

“A review of flight data recorder (FDR) data revealed that about two seconds after rotation, the left engine propeller rpm decreased to 60 percent and the left engine torque increased off-scale (beyond 5,000 ft-lb), which is consistent with the left propeller travelling to the feathered position and the engine torque increasing in an attempt to maintain propeller rpm,” the NTSB report said.

The crew applied full-right rudder trim to counter the asymmetric thrust while shutting down the left engine and then attempted to return to the airport. “It is likely that the flight crew did not readjust the trim when the drag was alleviated, which resulted in the airplane being operated in a cross-controlled attitude for about 50 seconds,” the report said.

Although the 1900 should have been able to climb at about 500 fpm, it slowed and stalled at about 300 ft, the report said. The pilots and their two passengers were killed when the airplane struck terrain.

Impact damage precluded a conclusive determination of what caused the uncommanded feathering of the left propeller. The report discussed the possibility that the propeller’s beta valve was not properly adjusted and that this had not been discovered during maintenance or preflight preparations.

The FDR data revealed that the pilots likely had not conducted the “Before Takeoff” checklist, which includes a propeller check that would result in an uncommanded feathering if the beta valve was misrigged.

The NTSB determined that a contributing factor in the accident was “the flight crew’s failure to establish a coordinated climb once the left engine was shut down and the left propeller was in the feathered position.”

Rapid Depressurization

Bombardier Q400. No damage. No injuries.

The aircraft was climbing through 17,000 ft during a flight with 54 passengers and four crewmembers from Birmingham, England, to Aberdeen, Scotland, the afternoon of Feb. 3, 2016, when the flight crew heard a loud noise and the sound of rushing air. They initiated an emergency descent, donned oxygen masks and diverted to Manchester, where the airplane was landed without further incident.

The AAIB report noted that both pilots experienced sensations of light-headedness, tightness of the chest and tingling of the fingers before they began to use supplemental oxygen.

“The aircraft was inspected on the ground, paying particular attention to the condition of the door seals — no defects were found,” the report said. After the cabin pressure controller and the outflow valve were replaced, the pressurization system functioned normally during testing, and the Q400 was returned to service.

During subsequent examination by the manufacturer, the replaced outflow valve “failed a number of tests and was found to have contamination and wear issues,” the report said. “It is considered that the valve … had been responsible for the depressurization.”

Control Lost on Approach

Piper Mirage. Destroyed. One fatality.

Night instrument meteorological conditions (IMC) prevailed when the pilot initiated a global positioning system (GPS) approach to Lubbock, Texas, U.S., on Feb. 4, 2015. He had been advised by the approach controller that a regional jet pilot had reported moderate rime ice at 5,000 ft near the airport.

The single-turboprop airplane was at 5,600 ft, inbound to the intermediate fix, when the controller canceled the approach clearance and told the pilot to make a left turn and to climb to 7,000 ft for resequencing.

The NTSB report explained that the controller had to cancel the approach clearance to provide adequate spacing between the Mirage and a preceding aircraft.

The pilot’s acknowledgement of the controller’s instructions was his last radio transmission. Recorded radar data showed that the airplane continued the left turn past the assigned heading, climbed to 5,800 ft and then began to descend rapidly.

The Mirage struck a television tower guy wire and several power lines before descending onto an open field about 800 ft (244 m) from the airport traffic control tower.

Investigators determined that the airplane’s controllability during the go-around likely had been affected by structural icing and by wind gusts up to 31 kt. The NTSB concluded that the pilot likely became spatially disorientated in the night IMC, resulting in his loss of airplane control.

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Piston Airplanes

‘Scud Running’

Cessna 310H. Destroyed. Three fatalities.

The pilot and two passengers were attempting to return from the Bahamas to Winter Haven, Florida, U.S., the afternoon of Feb. 14, 2013. The weather over Florida was being affected by a cold front producing thunderstorms, marginal VMC and IMC.

The pilot held a private certificate with a multiengine rating, but he was not instrument-rated. The front-seat passenger (the “copilot”) held a commercial license and an instrument rating, but he was not instrument-current and did not have a multiengine rating.

Due to weather conditions not specified by the NTSB report, the pilot had to divert from Fort Pierce, the intended initial landing site, to West Palm Beach to clear U.S. Customs. While on the ground, the copilot contacted a flight service specialist, who advised that visual flight rules (VFR) operations were not recommended due to low cloud ceilings and visibility.

The 310 then proceeded north, toward Winter Haven. While obtaining clearance to fly through Class D airspace at Vero Beach, the copilot told the airport traffic controller that they were “scud-running up the coast” at 500 ft.

During a stop for unspecified reasons in Sanford, the copilot called a flight service specialist, who advised of adverse conditions along the route. He also called his wife, who said that the weather was “bad” in Winter Haven. Nevertheless, “the copilot likely advised the pilot to continue the flight,” the report said.

About 20 minutes after departing from Sanford, the copilot told an Orlando approach controller that they had inadvertently entered IMC. The controller issued a transponder code and told the copilot to establish radio contact with Miami Center. However, there was no further contact with air traffic control.

Recorded radar data showed that the 310 began a circling descent. “The wreckage was located the following day in a heavily wooded, deep-water swamp area [in Yeehaw Junction],” the report said. “No debris path was observed.”

The report noted that toxicological tests showed a high level of diphenhydramine in the pilot’s blood.

The NTSB concluded that the probable cause of the accident was “the non-instrument-rated pilot’s improper decision to continue VFR flight into IMC and his subsequent spatial disorientation.”

Contributing factors were “the copilot’s improper evaluation of weather conditions” and the pilot’s “cognitive and psychomotor impairment due to recent use of an over-the-counter sedating antihistamine, and [his] personal pressure to get home,” the report said.

Taxiway Landing

Beech C55 Baron. Substantial damage. No injuries.

The Baron was on downwind, abeam the runway threshold at Casey, Illinois, U.S., the morning of Feb. 27, 2016, when the right engine “sputtered” and then lost power. The left engine also lost power as the pilot turned toward what he thought was the runway.

“The pilot said he ‘flared, then bounced, floated and bounced again’ [before] the airplane ran off the paved surface, flew over a ditch and touched down in a plowed field, where all three landing gear collapsed,” the NTSB report said.

The pilot had inadvertently landed the Baron on a taxiway, rather than the runway. Damage during the overrun was substantial, but the pilot and his passenger escaped injury.

“The reason for the loss of engine power could not be determined because a postaccident test run of the engines did not reveal any anomalies that would have precluded normal operation,” the report said.

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Helicopters

Rotor Blade Strikes Cabin

Robinson R44. Destroyed. Two fatalities.

The R44 was being flown about 1,200 ft above the floor of a river valley at about 102 kt while returning to Queensland, New Zealand, during an instructional flight the afternoon of Feb. 19, 2015, when a main rotor blade struck the cabin, causing the helicopter to break up in flight. The student pilot and flight instructor were killed.

“The [rotor strike] was caused by a phenomenon known as mast bumping, when the inner part of a main rotor blade or the rotor hub contacts the main rotor driveshaft,” said the report by the New Zealand Transport Accident Investigation Committee (TAIC).

The committee was unable to determine conclusively what caused the mast bumping. “We found that it was unlikely to have been a low main rotor rpm event and could find no mechanical defect or failure that could have contributed to the accident,” the report said.

The report noted that, in addition to low rotor rpm, mast bumping can be caused by turbulence, a low-G condition or large and abrupt control applications.

Although calm weather conditions prevailed, the R44 might have encountered occasional light to moderate turbulence. “Light to moderate turbulence should not on its own cause mast bumping, but when combined with a relatively high speed and a pilot’s control response to any turbulence, there is a high risk of the helicopter entering a low-G condition, rolling rapidly to the right and suffering a mast bump event before the pilot can react,” the report said.

Accidents involving mast bumping usually are fatal, “leaving no one to explain what was happening at the time,” the report said. “There have been many other fatal mast bump accidents involving Robinson helicopters in New Zealand and around the world that have gone largely unexplained.”

The TAIC said that difficulty in learning lessons from such accidents and formulating actions to prevent them is “a serious safety issue that the industry, including pilots, operators, the manufacturer and the regulator, will need to address.”

“The causes and circumstances of helicopter mast bumping accidents are unlikely to be fully understood until a means of recording cockpit imagery and/or other data is made available.”

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