‘Underestimation of Weather Conditions’

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

Long, Fast Touchdown

Boeing MD-83. Substantial damage. No injuries.

The flight crew’s “underestimation of the degradation of weather conditions … and failure to initiate a missed approach” led to a runway excursion at Port Harcourt International Airport, said the Nigerian Accident Investigation Bureau (AIB). The MD-83 was substantially damaged, but none of the 48 occupants was hurt in the accident, which occurred during a scheduled flight from Abuja the night of Feb. 20, 2018.

Convective activity prevailed at Port Harcourt. As the aircraft neared the airport, weather conditions were reported as 600 m (3/8 mi) visibility in heavy rain, a broken ceiling at 180 m (about 590 ft) and surface winds from 360 degrees at 22 kt. The weather report indicated that visibility was deteriorating.

A precision instrument approach was available only for Runway 21; however, the instrument landing system (ILS) glideslope was out of service. Rather than conducting an approach to Runway 30 with a headwind, the crew chose the localizer approach to Runway 21.

The first officer was the pilot flying, but the captain assumed control because he felt that the workload during the approach would be “too much” for the relatively inexperienced first officer, the AIB report said.

The approach controller advised the crew that there were thunderstorms along the approach path to Runway 21 and that the crew of another air carrier aircraft had conducted a missed approach to Runway 30 after encountering wind shear. The controller asked the MD-83 crew to state their intentions. “For various reasons, the crew decided to continue the approach” to Runway 21, the report said.

During the approach, the pilots did not ask for, and the airport traffic controller did not provide, an update on the weather conditions or runway braking action. As rainfall intensity increased, the captain told the first officer to watch for the runway. The aircraft was nearing the minimum descent altitude when the captain said that he had the runway in sight.

Indicated airspeed was 10 kt higher than the appropriate landing reference speed when the MD-83 crossed the runway threshold with a 19-kt tailwind. After an extended flare, the aircraft touched down with 1,871 ft (570 m) of the 9,843-ft (3,000-m) runway remaining. The report said the touchdown was “smooth” and that “the tyres did not firmly contact the wet runway.” The aircraft skidded on the centerline before veering off the left side of the runway about 200 ft (61 m) from the departure end.

“The public address system did not work; therefore, the lead [cabin crewmember] had to open the cockpit door to obtain emergency evacuation instructions from the captain,” the report said. “Emergency evacuation was carried out using the left forward main door only, and the escape slide on this door did not deploy. Airport rescue and fire fighting services arrived during the evacuation, and all persons on board were evacuated unhurt.”

Icing Triggers Stall

Embraer Phenom. Substantially damaged. No injuries.

The flight crew was conducting a charter flight the morning of Feb. 15, 2013, to Berlin-Schönefelt (Germany) Airport, which had 4,800 m (3 mi) visibility in mist and a 1,400-ft overcast. The pilots were advised by air traffic control (ATC) that moderate icing conditions had been reported below 3,000 ft near the airport.

The crew conducted the ILS approach to Runway 07L. “At about 3,000 ft, the aircraft entered the clouds and, approximately three minutes later, left them again at about 1,400 ft,” said the report by the German Federal Bureau of Aircraft Accident Investigation. The pilots activated the engine and windshield anti-ice systems but did not activate the wing and horizontal stabilizer deice systems. The report said they did not notice ice accumulating on the wings while descending through the clouds.

The Phenom was about 30 ft above the runway and being flared for landing when it stalled and rolled left and then right. The right wing and right main landing gear struck the runway. “The landing gear fractured, and the aircraft slid along the runway toward the right runway edge and came to a stop there,” the report said. Damage was substantial, but the pilots and their passenger were not hurt.

Ice-Covered Runway

Raytheon Hawker 400A. Substantial damage. No injuries.

Based on their preflight planning, the flight crew expected runway conditions at the destination — Burke Lakefront Airport in Cleveland, Ohio, U.S. — to be good, but as the airplane neared the airport the evening of Feb. 4, 2018, they found that light freezing rain was falling. Visibility was 4 mi (6 km), the ceiling was overcast at 700 ft and the surface winds were from 340 degrees at 17 kt, gusting to 25 kt.

The crew was cleared to conduct the ILS approach to Runway 24R and circle to land on Runway 06L. During their approach briefing, the captain told the first officer that the runway would be wet and they would have a 25-kt crosswind, the Hawker’s limit, while landing on Runway 06L.

“During the circling approach to Runway 06L, the airplane got too close to obstacles, and the crew elected to conduct a missed approach,” said the report by the U.S. National Transportation Safety Board (NTSB). The airport traffic controller advised that the surface winds now were from 010 degrees at 25 kt. The crew requested and received clearance to conduct another ILS approach to a landing on Runway 24R, which was 6,604 ft (2,013 m) long.

“After touchdown, the crew reported they applied maximum braking, but the airplane did not slow and skidded off the end of the runway, into the engineered material arresting system (EMAS),” the report said. The nose landing gear collapsed, and the fuselage was substantially damaged, but the pilots and their two passengers were not injured.

NTSB concluded that the probable cause of the accident was “the airplane’s reduced braking performance due to an ice-covered runway” and that a contributing factor was “the crew’s selection of a runway with a [16-kt] tailwind.”

Near Collision on Go-Around

Airbus A320, Saab 340B. No damage. No injuries.

The A320 was slightly above the glideslope during an ILS approach to Runway 22 at London Stansted Airport the evening of Feb. 12, 2019, and the commander advised the copilot, the pilot flying, to use the autopilot vertical speed mode to increase the descent rate. However, the copilot inadvertently initiated a climb. “Recognising there was no prospect of a stable approach, the commander ordered a go-around,” said the report by the U.K. Air Accidents Investigation Branch.

The copilot disengaged the autopilot, and the commander set the flight director for the missed approach procedure, which called for an initial climb on runway heading, 220 degrees, to 3,000 ft. “There was some confusion between the pilots over speed and flap selections, [and the commander] took control of the aircraft,” the report said.

ATC told the crew to climb to 4,000 ft and turn left to a heading of 090 degrees. There was a delay in the crew’s response to the instructions. “The flight director was still giving directions to fly the aircraft along the planned navigation path for the published go-around, so the commander did not engage the [autopilot],” the report said. “He made a slight turn to the right and then immediately corrected to the left and ordered the copilot to set heading 090 degrees.”

Meanwhile, the flight crew of the Saab had been cleared for takeoff from Runway 22. “As the aircraft passed approximately 1,000 ft, the crew were advised by ATC that an aircraft on approach had initiated a go-around,” the report said. “Shortly after this, ATC instructed the crew to turn onto a heading of 290 degrees … and to stop climb at 3,000 ft.”

The Saab was climbing through 2,500 ft when the crew received a traffic-alert and collision avoidance system (TCAS) traffic advisory. Shortly thereafter, the TCAS issued a resolution advisory instructing the crew to level off at 2,700 ft.

Investigators determined that the aircraft passed within 285 ft (87 m) laterally and 600 ft vertically before the conflict was resolved. The report said that the Saab crew’s adherence to the TCAS resolution advisory “prevented a further degradation of separation.” There were 187 people aboard the A320 and 21 people aboard the Saab.

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Turboprops

‘A Little out of Control’

Cessna 441. Destroyed. Three fatalities.

Instrument meteorological conditions (IMC) prevailed when the 441 departed from Eagle Creek Airpark in Indianapolis, Indiana, U.S., on a business flight the night of Feb. 22, 2018. The departure controller noticed that the airplane was deviating from its assigned altitude and heading and queried the pilot about the deviations.

The NTSB report said the pilot replied that the airplane was “a little out of control.” He later said that he had a “trim problem” and was having difficulty controlling the airplane but had returned to straight-and-level flight. The departure controller issued a vector to get the airplane back on course, cleared the pilot to climb to 13,000 ft and switch to an air route traffic control center frequency.

When the pilot established radio communication with the center controller, he was cleared to climb to Flight Level 230 (approximately 23,000 ft). “The pilot then transmitted that he needed to get control of the airplane and [said] ‘my trim is kind of going out on me,'” the report said. “Communications and radar contract were then lost.”

“It is likely that the pilot was unable to maintain control of the airplane as he attempted to address the trim issues that he reported to air traffic control,” the report said. The 441 crashed in a field in Rossville, Indiana, at high speed and in a relatively level attitude, killing the pilot and his two passengers. Partly due to the fragmented wreckage, investigators were unable to determine what caused the trim problem.

Crossed Controls

ATR 72. Substantial damage. One serious injury.

The ATR 72 encountered a strong wind shear while descending through 8,500 ft to land in Sydney, New South Wales, Australia, the afternoon of Feb. 20, 2014. The encounter caused a rapid decrease in the tailwind component and an increase in indicated airspeed. “The airspeed trend vector (displaying predicted speed on the primary flight display) likely indicated well above the maximum operating speed (V_mo) of the aircraft of 250 kt,” said the report by the Australian Transport Safety Bureau. “The first officer [the pilot flying] reduced engine power and made nose-up control inputs in an attempt to slow the aircraft.”

“The captain took hold of the controls and made nose-up pitch control inputs without immediately following the specified takeover procedure and alerting the first officer of his intent,” the report said. “The first officer (unaware that the captain was also making control inputs) reversed his control input.” The differential forces reached an intensity that caused activation of the pitch-uncoupling mechanism, disconnecting the linkage between the left and right pitch control systems.

The subsequent asymmetric elevator deflections resulted in an in-flight upset that caused an exceedance of the limit load on the horizontal stabilizer and substantial damage to the stabilizer. The senior cabin crewmember suffered a fractured leg when she was thrown from her seat. None of the other occupants was hurt.

The flight crew landed the ATR 72 in Sydney without further incident. The damage to the stabilizer was not detected by maintenance engineers during a post-flight inspection, and the aircraft was released to service. “During the next five days, the aircraft was operated on 13 flights,” the report said. “No one identified any anomalies until a flight crew observed some damage after a suspected bird strike. The aircraft was grounded and subjected to extensive maintenance that included replacement of the horizontal and vertical stabilisers.”

Control Lost in a Winter Storm

Socata TBM 700A. Destroyed. Two fatalities.

A winter storm warning had been issued for the destination in Evanston, Wyoming, U.S., on Feb. 18, 2018. As the TBM 700 neared the airport after 3.5 hours of flight, the automated surface observing system (ASOS) was reporting 2 mi (3,200 m) visibility in light snow and mist, an 800-ft broken ceiling and surface winds from 290 degrees at 17 kt.

The pilot requested and was cleared to conduct the ILS approach to Runway 23. When the airplane crossed the final approach fix, the ASOS was reporting 1/4 mi (400 m) visibility in snow and freezing fog.

“About 1.6 miles [2.6 km] from the runway threshold, the airplane began a climb consistent with the published missed approach procedure,” the NTSB report said. “However, rather than completing the slight left climbing turn toward the designated holding point, the airplane continued in an approximate 270-degree left turn, during which the airplane’s altitude varied, before entering a descending right turn and impacting terrain. Tree and ground impact signatures were consistent with a 60-degree nose-low attitude at the time of impact.” The pilot and his passenger were killed, and the TBM 700 was destroyed by the impact and subsequent fire.

NTSB concluded that the pilot likely lost control of the airplane while experiencing spatial disorientation in restricted visibility and turbulence encountered during the approach.

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Piston Airplanes

‘Self-Induced Pressure’

Cessna T310Q. Destroyed. Four fatalities, one serious injury.

A witness said that the pilot appeared to be rushed and his four passengers anxious to depart from Riverside (California, U.S.) Municipal Airport for a flight to San Jose the afternoon of Feb. 27, 2017.

The pilot was unsuccessful in his first attempt to start the 310’s engines. “The occupants deplaned and waited for some time,” the NTSB report said. “During a second attempt to begin the flight, a ground controller informed the pilot that he was required to file an instrument flight rules (IFR) flight plan before departure.” IMC, with 2 mi visibility in light rain and mist, prevailed at the airport.

The pilot sought help from a flight school employee in filing the IFR flight plan. The 83-year-old pilot had 9,600 flight hours and held an instrument rating, but investigators were unable to determine when he had last flown in IMC or completed an instrument competency check.

“However, it is likely that the pilot was not instrument-current, as he was unfamiliar with basic instrument flight planning procedures and had to be coached through the readback of his IFR clearance,” the report said. “The pilot’s decision to complete the flight despite the IFR weather conditions was likely driven by his own self-induced pressure, influenced by the passengers’ need to return home.”

Shortly after takeoff, the 310 entered clouds at 900 ft and began a turn. The airplane then stalled and descended into several residences. The pilot and three passengers were killed, and one passenger was seriously injured. No one on the ground was hurt.

Fuel Exhaustion

Piper Seneca III. Substantial damage. One serious injury.

Before departing from Galliano, Louisiana, U.S., to photograph an offshore oil rig 185 nm (343 km) south on the afternoon of Feb. 6, 2018, the pilot told a passenger that the fuel tanks had not been topped off but contained about 80 gal (303 L) of fuel.

The Seneca’s aft cabin door had been removed to facilitate the aerial photography, and airspeed consequently was limited to a maximum of 130 kt. “The flight arrived at the oil rig about 1 hour 20 minutes after takeoff, and the pilot proceeded to circle for about 30 minutes,” the NTSB report said.

The pilot then noticed that the fuel gauges indicated about 20 gal (76 L) remaining — less than he expected for the return flight to Galliano. “With concern about the amount of fuel remaining, he leaned the engine mixtures as much as possible,” the report said. The pilot also diverted the flight to Patterson, Louisiana, which was closer than Galliano. According to the airplane flight manual, fuel flow at the economy cruise power setting was 20 gal per hour.

The right engine lost power due to fuel exhaustion about 24 nm (44 km) from Patterson. Shortly thereafter, the left engine lost power. The pilot conducted a forced landing in a canal. Damage to the Seneca was substantial, and one passenger sustained serious injuries; the other two passengers and the pilot were not hurt.

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Helicopters

Directional Gyro Mis-Set

Sikorsky S76C. Substantial damage. No injuries.

About 15 minutes after departing from an offshore platform for the return flight to Lagos, Nigeria, the morning of Feb. 3, 2016, the flight crew saw the “TRIM FAIL” warning light illuminate several times. The autopilot disengaged, and the first officer, the pilot flying, felt the flight control forces become heavy and unresponsive. The S76C then entered a rapid descent.

The first officer regained control about 1,000 ft above the water. “The instrument readings were inaccurate and inconsistent, and the aircraft started drifting to the right,” said the report by the Nigerian AIB. The captain assumed control of the helicopter and declared an emergency. The report said she decided that the helicopter could not be flown safely to a landing in Lagos, and told ATC and her passengers that they would have to ditch the helicopter.

The crew activated the helicopter’s emergency flotation devices and ditched the S76 in the Atlantic Ocean about 77 nm (143 km) from Lagos. The helicopter rolled over and sank shortly after the nine passengers and the two pilots evacuated without injury into life rafts. They were rescued by the crew of a boat.

Investigators found that the flight crew had switched the helicopter’s directional gyro to the “FREE” mode while landing on the offshore platform and had not returned it to the “SLAVE” mode before takeoff. The resulting unsynchronized heading inputs caused the trim failure and disengagement of the autopilot, the report said.

Control Lost on Landing

Bell 206L-4. Substantial damage. One serious injury.

The pilot was conducting the third leg of a charter flight in Papua, Indonesia, the morning of Feb. 3, 2016. The LongRanger was in a right turn while approaching a helipad in Bayabiru at 30 ft and an airspeed between 10 and 15 kt when it entered a spin to the right.

“The pilot pushed the cyclic stick with intention to gain speed and applied left rudder pedal to recover [from] the spin,” said the report by the Indonesian National Transportation Safety Committee (KNKT).

However, the pilot was unable to recover from the spin before the helicopter struck the roofs of two houses. The pilot sustained serious injury, but his three passengers were not hurt. No one on the ground was injured. The KNKT concluded that the accident was caused by “a loss of tail rotor effectiveness at a height too low to the terrain to complete a successful recovery.”

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