Six-Second Float

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

Six-Knot Tailwind

Boeing 737-900ER. Serious damage. No injuries.

The runway at Yogyakarta, Indonesia, was reported as wet, but there was no braking action report available. In addition, although the flight crew was told that surface winds were calm, there actually was a 6-kt tailwind on final approach. Investigators for the Indonesian National Transportation Safety Committee (KNKT) determined that braking action likely was either good or medium and that, even with the tailwind, the aircraft could have been landed safely if properly flown.

The KNKT determined that the aircraft was not properly flown. The flight crew did not conduct a stabilized approach or consider a go-around. Airspeed was 13 kt above the target speed when the 737 touched down after a long float. Deceleration on the wet runway was mishandled, and the aircraft ended up off the departure threshold.

The accident occurred on Nov. 6, 2015, during a flight from Jakarta with 161 passengers and seven crewmembers. The Yogyakarta airport was reporting visual meteorological conditions (VMC) with surface winds from 210 degrees at 10 kt. The pilots planned to conduct the instrument landing system approach to Runway 09, which was 2,200 m (7,218 ft) long.

As the aircraft neared the airport, the weather radar system displayed a precipitation level corresponding with cumulonimbus activity over the field. The crew decided that, rather than using the maximum flap setting (flaps 40) for the landing, they would use flaps 30, which was recommended when wind shear is possible. However, there were other factors to consider: “This change of landing flap configuration would increase the landing speed and the landing distance,” the report said. “There was no recalculation of the required landing distance following the landing configuration change.”

Although the lower flap setting, by itself, would not have precluded a landing, the knowledge of the longer landing distance with that configuration might have prompted the pilots to conduct a go-around when the approach became unstable, the report said.

During the approach, the airport traffic controller confirmed that the runway was wet but advised the pilots that the winds were calm. The captain flew the approach manually. Airspeed was more than 10 kt above reference speed, but the first officer (the pilot monitoring) made no airspeed callouts, and there was no discussion of going around. During the flare, the aircraft floated for six seconds and then touched down 730 m (2,395 ft) from the approach threshold. Airspeed on touchdown was 13 kt above reference speed.

Maximum reverse thrust initially was applied, but the thrust reversers subsequently were stowed about 16 kt above the recommended airspeed, which reduced deceleration. The captain also applied manual braking, overriding the autobrakes, in an attempt to slow the aircraft, but this action actually reduced braking performance. The nose landing gear collapsed, and the aircraft was substantially damaged when it overran the runway. None of the occupants was injured.

Escape Slide Malfunctions

McDonnell Douglas MD-11F. No damage. One serious injury.

The freighter was en route from Memphis, Tennessee, U.S., to Minneapolis, Minnesota, the morning of Feb. 24, 2015, when the flight crew observed an indication that the fire-suppression system in the cargo compartment had activated. They decided to divert to St. Louis, Missouri, where the airplane was landed without further incident.

“After exiting the runway and bringing the airplane to a stop in a safe area, the crew initiated an emergency evacuation using the left forward door,” said the report by the U.S. National Transportation Safety Board (NTSB). “The door opened; however, the escape slide/raft did not fully deploy, appearing to be hung up on a strap.” During attempts by the first officer and airport fire/rescue personnel to free the slide, it appeared to inflate.

“However, because the slide inflation sequence had been interrupted, it was significantly underinflated and unable to support the weight of [the first crewmember who attempted to evacuate],” the report said. The crewmember was seriously injured on contact with the ground. The other three occupants subsequently deplaned without injury.

The indication that the fire suppression system had activated was found to have been a false alarm.

Collision With Deicing Vehicles

Airbus A320-216. Minor damage. No injuries.

The A320 had 110 passengers and six crewmembers aboard for a flight from Munich to Madrid the morning of Jan. 20, 2016. The first officer was reading the current automatic terminal information system report to the captain when the aircraft was taxied at about 20 kt past the entrance to the deicing stand. The ground controller noticed this, advised the crew of the situation and cleared them to turn around at a taxiway intersection, said the report by the German Federal Bureau of Accident Investigation.

Upon reaching the deicing stand, the pilots began to conduct the Before Deicing checklist. One of the items on the checklist was to select the DITCHING switch to the ON position to close a cabin pressure outflow valve. However, the co-pilot inadvertently activated the forward cargo compartment fire-extinguishing system instead. The crew radioed the deicing team leader, “We need to go back to parking. … We have one problem.”

The team leader replied, “You have technical problems. We will wait.” The report said that he apparently did not understand that the crew needed to taxi the aircraft back to the parking stand and believed they would hold position while attending to the technical problem. The two deicing vehicles maintained their positions on both sides of the airplane, about 4 to 5 m (13 to 16 ft) in front of the wings.

The pilots apparently believed they had clearly communicated their intentions to the deicing team leader. The first officer told the ground controller that they needed to return to the parking stand. The controller instructed the crew to hold position and monitor the tower control frequency. About three minutes later, the tower controller cleared the crew to return to the stand.

The crew apparently did not communicate with the deicing team leader or ensure that the deicing vehicles were clear of the aircraft before releasing the parking brake and increasing thrust to begin taxiing. Seeing this, the team leader radioed, “What are you doing? … Please stop now.”

The crew immediately stopped the aircraft. However, the wings had struck the booms on the deicing vehicles and had tipped the vehicles about 20 degrees. The collision caused minor damage to the aircraft but substantial damage to the deicing vehicles. No one was hurt.

Caught in the Wake of a Heavy

Cessna Citation 550. Substantial damage. One minor injury.

The Citation, operated by the U.S. Customs Service, was returning to land at Oklahoma City, Oklahoma, U.S., after a training flight the morning of Dec. 21, 2012. The tower controller told the flight crew to extend their downwind leg. “The controller then called out the landing traffic on final, which was an Airbus A300-600 heavy airplane,” the NTSB report said. “The flight crew replied that they had the traffic in sight, and the controller cleared the flight to land behind the Airbus and to be cautious of wake turbulence.”

The Citation pilots planned to add 10 to 15 kt to their landing reference speed, conduct a steeper-than-normal approach and land beyond the A300’s touchdown point. However, investigators determined that the Citation was flown too closely behind the Airbus.

The Citation was about 150 ft above the ground on final approach when it encountered the vortex produced by the A300’s right wing. The airplane rolled left and pitched nose-down. The left bank angle had reached 60 degrees when the co-pilot applied full power while the pilot used both hands on the yoke attempting to recover control.

“He managed to get the airplane nearly back to level when the right main gear struck the ground short of the threshold and left of the runway,” the report said. “The airplane collided with a small drainage ditch and a dirt service road, causing the right main gear and the nose gear to collapse.” The Citation came to a stop in a grassy area between the runway and a taxiway. The pilot escaped injury, but the co-pilot was taken to a hospital and treated for back pain.

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Turboprops

‘Plan Continuation Bias’

De Havilland DHC-8-102. Substantial damage. No injuries.

VMC with visibilities temporarily decreasing to 3 mi (4,800 m) in light snow showers were forecast for the Dash 8’s destination — Sault Ste. Marie Airport in Ontario, Canada — the night of Feb. 24, 2015. Surface winds were from 310 degrees at 22 kt, gusting to 29 kt. The flight crew decided to conduct the VOR/DME (VHF omnidirectional range/distance measuring equipment) approach to Runway 30.

The aircraft was descending through 3,000 ft when the pilots acquired visual contact with the airport. However, they also observed that a snow shower was moving rapidly toward the runway from the west. “They reported these conditions to the controller, who cleared the flight for a visual approach, instructing them to deviate as necessary from the VOR approach,” said the report by the Transport Safety Board of Canada (TSB).

The aircraft was 5 nm (9 km) from the runway when the controller advised the crew that “a line of weather currently [was] rolling across the runway” and that runway visual range had decreased to 1,000 m (3,000 ft). “The [pilot monitoring] replied that they could see the approaching weather,” the report said.

“At some point below 200 feet, the flight crew lost visual reference to the ground due to the approaching weather system of blowing snow,” the report said. “The [visual] approach was continued.”

The aircraft touched down in deep snow about 450 ft (137 m) short of the runway threshold, struck an approach light and came to a stop on the runway. The nose landing gear collapsed, causing substantial damage to the aircraft, but none of the 18 occupants was hurt.

The TSB concluded that among the causes of the accident was that “the loss of visual reference required a go-around, [but] the crew continued the approach to land as a result of plan continuation bias.” The report said, “Plan continuation bias can be described as a ‘deep-rooted tendency of individuals to continue their original plan of action even when changing circumstances require a new plan.’”

Stall on Final Approach

Cessna 441 Conquest. Substantial damage. One fatality.

The pilot was conducting a global positioning system approach to Denton, Texas, U.S., where instrument meteorological conditions (IMC) with light to moderate turbulence prevailed on the night of Feb. 4, 2015. “While receiving radar vectors to the final approach course, the pilot did not always immediately comply with assigned headings and, on several occasions, allowed the airplane to descend below assigned altitudes,” the NTSB report said.

The airplane was 500 ft below the published minimum altitude as it neared the final approach fix. “The tower controller subsequently alerted the pilot of the airplane’s low altitude, and the pilot replied that he would climb,” the report said. At this time, the 441’s airspeed had decreased from 162 kt to 75 kt.

“The pilot made an abrupt elevator-up input that further decreased airspeed, and the airplane entered an aerodynamic stall,” the report said. “A witness saw the airplane abruptly transition from a straight-and-level flight attitude to a nose-down, steep left bank [and enter] a vertical descent toward the ground.” The pilot was killed when the 441 struck terrain about 6 nm (11 km) from the runway.

“A post-accident examination of the airplane did not reveal any anomalies that would have precluded normal operation during the accident flight,” the report said.

A Question of Control

ATR 72-600. Substantial damage. No injuries.

The first officer, who was receiving line training, was the pilot flying on a scheduled flight to Lombok, Indonesia, the morning of Feb. 3, 2015. VMC prevailed at the airport, with surface winds from 210 degrees at 12 kt. The flight crew conducted a visual approach to Lombok’s Runway 13. During the approach briefing, the captain emphasized that the landing would be made with a crosswind, according to the KNKT report.

The report said that the captain assisted the first officer in aligning the aircraft with the runway centerline twice during the approach. “Further, at below 500 ft, the [captain] took over control and instructed the [first officer] to follow in controlling the aircraft,” the report said. The captain then cautioned the first officer that the aircraft was below the proper flight path and that the descent rate was excessive. This indicates that the captain transferred control back to the first officer, with no specific verbal communication.

“It can be concluded that transfer of control occurred two times on short final, which is a critical phase of flight,” the report said, adding that the absence of required verbal communication of the transfer of control may have resulted in the first officer not being “fully aware” of who was in control.

The ATR touched down about 700 m (2,297 ft) from the approach threshold, bounced twice and then veered off the right side of the runway. The aircraft’s landing gear collapsed during the excursion, but none of the 34 occupants was injured during the excursion and subsequent evacuation.

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Piston Airplanes

Refueled With Jet-A

Piper Malibu. Destroyed. One fatality.

En route from Canada, the pilot landed at Spokane, Washington, U.S., the afternoon of Feb. 22, 2015, to clear U.S. Customs and to refuel his airplane. The pilot did not specify that the Malibu was to be refueled with aviation gasoline (avgas). “The refueler mistakenly identified the airplane as requiring Jet-A fuel, even though the fuel filler ports were placarded ‘AVGAS ONLY,’” said the NTSB report. “The refueler subsequently fueled the airplane with Jet-A instead of aviation gasoline.”

A contributing factor to the misfueling was that the fixed-base operator’s Jet-A fuel truck was equipped with the wrong nozzle. “Jet-A and avgas fueling nozzles are different designs in order to prevent refueling an airplane with the wrong type of fuel,” the report said. The fuel truck had an avgas nozzle, and 52 gal (197 L) of Jet-A were added to the Malibu’s tanks.

The pilot did not observe the refueling and subsequently, while signing the receipt, did not notice a notation that the airplane had been serviced with Jet-A. “It is unknown if the pilot visually inspected or obtained a fuel sample before takeoff,” the report said. “Had the pilot done this, it would have been apparent that the airplane had been improperly fueled.”

The Malibu was on initial climb when the engine lost power. The airplane was destroyed, and the pilot was killed, during the subsequent forced landing in a railroad yard.

Full Flaps Foil a Go-Around

Piper Seneca III. Substantial damage. No injuries.

The pilot told investigators that he did not conduct a full preflight check before departing from Senai, Malaysia, for a flight to Seletar, Singapore, the afternoon of Jan. 1, 2016. “The items that he omitted checking included the flap system,” said the report by the Transport Safety Investigation Bureau of Singapore.

The aircraft’s flap system includes a floor-mounted control lever. “Flap selection [is] made by depressing a button (plunger plug) on the end of the flap control lever and shifting the lever to the desired flap position,” the report said.

The pilot said that when he selected full flaps for the landing at Seletar, he felt a “sticky resistance” when he attempted to depress the button on the lever. However, he was able to extend the flaps to the full 40 degrees.

The Seneca bounced on touchdown, and the pilot decided to conduct a go-around. “The pilot did not execute the go-around in accordance with the procedure prescribed in the flight manual,” the report said. He applied full power and attempted to raise the flaps but was unable to depress the button on the lever. “[He] then raised the landing gear without first checking that the aircraft had achieved a positive climb,” the report said.

With the flaps fully extended, the Seneca began to descend. It touched down with the landing gear retracted and slid to a stop on the runway. “The propellers of both engines had curled, and the belly area of the aircraft was damaged,” the report said. The pilot was not injured.

Examination of the flap system indicated that it was operating normally. “Nevertheless, if, as the pilot said, the button had some stickiness problem, then this would likely have been discovered before taking the aircraft to the air had he carried out the preflight check thoroughly,” the report said.

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Helicopters

‘Unrecognized Descent’

Bell 206B. Destroyed. One fatality, two serious injuries.

An air taxi flight from an oil tanker anchored in a bay near Galveston, Texas, U.S., had been delayed more than two hours by low visibility the evening of Feb. 6, 2017. However, the pilot said that visibility was more than 6 mi (10 km) when he departed from the ship with two passengers for the flight to Santa Fe, Texas.

The pilot told investigators that he initially flew between 700 and 800 ft. “He added that as the flight approached the shore at 500 feet, he could see the city lights and lights off the water,” the NTSB report said. “The next thing he remembered was being in the water.” During the impact, one passenger was killed, and the other passenger and the pilot were seriously injured. They were rescued by the Coast Guard about an hour later.

The report said that the nearest weather station, 8 nm (15 km) from the accident site, was reporting 5 mi (8 km) visibility and a 400-ft overcast. NTSB concluded that the probable cause of the accident was “the pilot’s failure to recognize the flight had encountered [IMC] at night, which resulted in an unrecognized descent and collision with water.”

No One at the Controls

Robinson R22. Substantial damage. No injuries.

After conducting a reconnaissance flight in preparation for a goat-mustering flight the morning of Feb. 11, 2015, the pilot landed the R22 near Kalibarri, Western Australia, where his passenger disembarked. The pilot then realized that before beginning the mustering operation, he needed to resolve some confusion about some landmarks the passenger had pointed out.

“Rather than shut down the engine, the pilot elected to leave the helicopter running,” said the report by the Australian Transport Safety Bureau. “After applying cyclic and collective control friction, he disembarked [from] the helicopter to follow the passenger.”

The pilot said that he talked with the passenger for about two minutes. “Just as the pilot and passenger had concluded their conversation, the pilot heard the helicopter’s engine rpm increase and almost simultaneously noticed that the helicopter was lifting clear of the ground,” the report said.

The R22 climbed about 13 ft, yawed about 80 degrees left, traveled backward about 8 m (26 ft) and descended in a nose-high attitude. The tail rotor blades separated when they struck the ground, and the left skid collapsed. “The helicopter settled upright; but during the accident sequence, the main rotor blades struck the ground and stopped abruptly,” the report said. “When the pilot was satisfied that it was safe to approach the helicopter, he moved forward and shut the engine down.”

The pilot told investigators he believed that, despite the application of the control friction systems, vibrations in the helicopter caused the collective to move upward and engine power to increase. “He also commented that he was surprised at how quickly the accident happened,” the report said. “From the moment he heard the engine rpm begin to increase to the collision with terrain was only a few seconds.”