One Aircraft on Final, One on the Runway

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

Clearance Readback Omitted

Boeing 737-900ER, ATR 72-500. Substantial damage. No injuries.

A last-minute evasive maneuver by the pilot landing a 737 at Kualanamu International Airport in Medan, Indonesia, the morning of Aug. 3, 2017, prevented what could have been a much more serious collision with an ATR 72 that had strayed onto the runway centerline. Rather than potentially disastrous fuselage contact, the maneuver led to contact between the 737’s left wing and the ATR’s right wing. Both aircraft were substantially damaged, but none of the 158 people aboard the jet or the 72 people aboard the twin-turboprop was injured.

The investigation by the Indonesian National Transportation Safety Committee (KNKT) concluded that factors contributing to the accident were the ATR flight crew’s lack of awareness that the 737 was on short final approach and their misunderstanding of an airport traffic (tower) controller’s conditional clearance that was meant to instruct the crew to line up for takeoff on the runway after the 737 landed and passed by their taxiway. The clearance did not conform to recommended standards of delivery and phraseology, and the controller did not receive confirmation of the clearance by the ATR flight crew, according to the KNKT report.

Baggage-handling problems had delayed the ATR’s departure, and while taxiing to Runway 23, the crew attempted to expedite their departure by requesting clearance to depart from Delta Intersection, which was about 2,200 ft (671 m) from the approach threshold of Runway 23. The tower controller approved the request and, intending to sequence the ATR’s departure between the 737’s landing and the arrival of another aircraft on approach, asked the ATR crew if they would be ready for an immediate departure. The crew said that they would be ready.

The report said that the controller subsequently issued the following clearance to the ATR crew: “Behind traffic [on] short final landed passing line up behind Runway Two Three from Intersection Delta.” These instructions were immediately followed by an initial route clearance.

The ATR’s copilot, the pilot monitoring (PM), was handling radio communications. “The PM, who [had] relatively low experience (109 flight hours), was unable to receive all the information of the clearance, [which] was delivered faster than required,” the report said. The PM read back only the initial route clearance.

The tower controller did not confirm that the ATR crew had the 737 in sight or that they understood they were to line up on the runway after the 737 landed and passed by Delta Intersection. The report said that the ATR pilots were not aware of the 737; they had been communicating with a ground traffic controller moments earlier, when the tower controller cleared the 737 crew to land. The report noted that Delta Intersection is a rapid-exit taxiway for aircraft landing in the opposite direction, on Runway 05, and is at an acute angle to Runway 23. This orientation would increase the difficulty of a crew holding short on Delta to check for traffic on approach, the report said.

The 737 was 37 ft above the ground when the pilots saw the ATR moving close to the intersection holding line. Although they suspected that the ATR might enter the runway, they did not attempt a go-around. Investigators agreed with this decision. “Taking into account an expected height loss shortly after a go-around is initiated, a go-around executed as the aircraft was descending through 37 feet would most likely not have avoided the collision [and] may have resulted in more severe circumstances,” the report said.

The tower controller was monitoring arriving aircraft on a radar display and did not see the ATR enter the runway. After the 737 touched down, the captain maneuvered to the right of the runway centerline. The collision occurred about two seconds later. “Debris from the impact remained on the runway,” the report said. “Prior to the runway inspection, one aircraft departed and one aircraft landed.”

Hard Landing Follows Computer Failure

Airbus A319. Substantial damage. No injuries.

The A319 was 1,500 ft above the ground during an instrument landing system (ILS) approach to Munich, Germany, on July 3, 2017, when the no. 1 flight management guidance computer failed. “The crew were unable to alter the target approach speed, and the engines began to spool up uncommanded,” said the report by the U.K. Air Accidents Investigation Branch. “The pilot flying [the first officer] disconnected the autopilot and autothrust, and the rest of the approach was flown manually.”

The aircraft was 30 ft above the runway when the first officer reduced the pitch attitude to about 1 degree nose-down. The A319 touched down hard — at 3.01 g (that is, 3.01 times standard gravitational acceleration) — and in a relatively flat attitude. “The commander did not notice the control input because he was looking ahead and did not notice the abnormal landing attitude until it was too late to act effectively,” the report said.

None of the 155 occupants was injured, but the aircraft’s right main landing gear and nose landing gear were substantially damaged in what was classified as a “severe hard landing,” the report said. The aircraft was returned to service after all three landing gear were replaced.

‘Pumping the Brakes’

Eclipse 500. Substantial. Three minor injuries.

Visual meteorological conditions (VMC) prevailed at Danbury (Connecticut, U.S.) Municipal Airport the afternoon of Aug. 21, 2015, as the pilot prepared to land on Runway 26. He said that the landing “required a steeper than normal approach” because of trees on the approach path.

The pilot told investigators that after the airplane touched down near the displaced threshold, brake pedal application felt soft, so he continued “pumping the brakes” during the landing roll. The pilot considered going around but decided there was insufficient runway remaining. The Eclipse ran off the end of the runway, struck a berm and came to rest upright about 200 ft (61 m) from the threshold. The nose landing gear separated and the right main landing gear punctured the right wing during the overrun. The three occupants of the airplane sustained minor injuries.

Investigators determined that the airplane had landed long on the 4,422-ft (1,348-m) runway, which had a 737-ft (225-m) displaced threshold. “Estimated landing distance calculations revealed that the airplane required about 3,063 ft [934 m] when crossing the threshold at 50 ft above ground level,” the report said. “However, the airplane touched down with only 2,048 ft [624 m] of remaining runway, which resulted in the runway overrun.”

Wind Shear Triggers Undershoot

Boeing 737-300F. Substantial damage. No injuries.

During final approach to Runway 15 at Wamena (Indonesia) Airport the afternoon of Aug. 28, 2015, the flight crew was advised that surface winds were from 150 degrees at 15 kt. The KNKT report indicated that the airport controllers did not have access to, or did not provide the pilots with, information on gusts or variations in wind speed and direction, which might have been clues to wind shear on the approach path.

The investigation showed that the approach was stable until the aircraft encountered wind shear about 300 ft above the ground. The headwind increased from 19 kt to 25 kt, causing an increase in the 737’s indicated airspeed. Apparently in reaction to this, the pilot flying (the pilot-in-command) reduced thrust substantially. Indicated airspeed then decreased from 151 kt to 129 kt, and the descent rate increased to 1,320 fpm.

The freighter touched down hard on the left main landing gear about 35 m (115 ft) from the runway threshold. The left main landing gear collapsed and the left engine struck the runway surface before the 737 stopped about 1,500 m (4,922 ft) from the threshold. Neither of the two pilots was injured.

The KNKT determined that the thrust reduction was a contributing factor in the accident. “The large thrust reduction was not in accordance with the FCOM [Flight Crew Operating Manual] for wind shear precaution and resulted in a rapid descent,” the report said. The FCOM says that large thrust reductions should be avoided when a sudden increase in airspeed occurs.

No Warning of Severe Turbulence

Airbus A340-300E. Minor damage. Four serious injuries, 17 minor injuries.

The A340 was cruising at Flight Level 370 (approximately 37,000 ft) over Malaysian airspace during a flight from Kempton Park, South Africa, to Hong Kong the morning of July 27, 2014, when it encountered severe clear air turbulence.

Two passengers and two cabin crewmembers were seriously injured, and 16 passengers and one cabin crewmember sustained minor injuries during the encounter, which lasted about eight seconds. “Damage was caused to overhead stowage panels when some occupants impacted the overhead panels with their heads,” said the report by the South African Civil Aviation Authority (CAA).

The flight crew apparently had received no warning of the turbulence. “The weather radar showed that the weather was clear at the time, with no clouds evident,” the report said.

The pilot-in-command, who was resting in a crew bunk when the turbulence encounter occurred, decided to continue the flight to the scheduled destination. “It is not clear why the crew continued to Hong Kong, when they had injuries on board, instead of landing [in] Malaysia,” the report said. The A340 was landed at Hong Kong about three hours after the turbulence encounter.

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Turboprops

Hydraulic Fluid Feeds Fire

Piper Cheyenne II. Destroyed. Four fatalities.

The Cheyenne was climbing through 14,900 ft in instrument meteorological conditions (IMC) during an emergency medical services (EMS) flight from Crescent City, California, U.S., to Oakland the night of July 29, 2016, when the pilot advised air traffic control (ATC) that he smelled smoke in the cockpit and was returning to Crescent City. The controller cleared the pilot to descend at his discretion to 9,000 ft.

“The pilot replied ‘OK’ and said that it looked like he was going to lose some power shortly,” said the report by the U.S. National Transportation Safety Board (NTSB). “The pilot then stated that he had smoke in the cockpit, declared an emergency and requested that ATC contact the fire department.” Shortly thereafter, the pilot advised that four people were aboard the airplane. This was his last radio transmission to ATC.

The wreckage was located nine hours later in a forest near McKinleyville, California. A debris path leading to the accident site indicated that the Cheyenne had experienced an in-flight breakup. The patient, two medical personnel and the pilot had been killed.

Examination of the wreckage showed that electrical arcing near the main bus tie circuit breaker panel, which is located between the two front seats, had ignited a fire. Nearby landing gear system hydraulic lines melted and released hydraulic fluid that fed the fire.

Investigators found electrical wires and hydraulic lines in direct contact in the same area in six other Cheyennes. “Some of the wires in the exemplar airplanes showed chafing between hydraulic lines and the electrical wires which, if left uncorrected, could have led to electrical arcing and subsequent fire,” the report said.

Strikes Mountain on Approach

Cessna 441. Destroyed. Five fatalities.

The 441 was nearing Cape Town, South Africa, during an EMS flight from Oranjemund, Namibia, the night of Aug. 16, 2015, when the flight crew was advised of a complete ATC radar failure in the area. IMC prevailed at the Cape Town airport. Although the ILS to Runway 19 was available, the approach controller cleared the crew to conduct a VOR (VHF omnidirectional radio) approach to that runway. The clearance for the nonprecision approach was issued to provide separation between the 441 and a departing aircraft, said the report by the South African CAA.

Shortly after establishing radio communication with the airport traffic controller, the crew reported that they were inbound on the VOR approach. The controller issued a clearance to land but received no response from the crew. About 90 minutes later, the crew of a search helicopter found the wreckage of the 441 about 8 nm (15 km) north of the airport. The patient, a passenger, a paramedic and the two pilots had been killed.

Investigators determined that the aircraft had deviated from prescribed courses and altitudes during the approach. “The mountain where the accident took place was covered with low-level clouds at the time of the accident,” the report said.

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Piston Airplanes

Checklists Not Followed

Piper Navajo. Substantial damage. Six fatalities.

The Navajo’s fuel tanks were topped off before the pilot departed with five passengers from Orlando, Florida, U.S., for a personal flight to Oxford, Mississippi, the morning of Aug. 14, 2016. The flight plan showed a fuel endurance of 5 hours and 10 minutes. “The airplane’s outboard tanks contained sufficient fuel for about 1 hour 45 minutes of flight,” the NTSB report said, noting that the airplane flight manual specifies that fuel be used from the outboard tanks for no more than 1 hour and 45 minutes during cruise flight before switching to the inboard tanks.

The Navajo had been in cruise flight at 12,000 ft for about 1 hour and 45 minutes when the pilot told ATC that the right engine fuel pump had failed. He requested, and received, vectors to Tuscaloosa, Alabama, the nearest airport. The airplane was 13 nm (24 km) from Tuscaloosa when the pilot told ATC that both fuel pumps had failed and that both engines had lost power.

“The pilot continued toward the diversion airport, and the airplane descended until it impacted trees about 1,650 ft [503 m] short of the approach end of the runway,” the report said. “Post-accident examination of the airframe and engines revealed no pre-impact failures or malfunctions that would have precluded normal operation.”

Investigators determined that the pilot likely had not switched from the outboard fuel tanks to the inboard tanks before or after the engines lost power. The NTSB concluded that the probable causes of the accident were “a total loss of power in both engines due to fuel starvation as the result of the pilot’s fuel mismanagement and his subsequent failure to follow the emergency checklist.”

An instructor who had flown with the pilot told investigators that the pilot had not received training in the airplane on single-engine operations and emergency procedures. The report said that this lack of training “[contributed] to the pilot’s failure to follow the emergency checklist.”

Disorienting Conditions

Cessna 414A. Destroyed. One fatality.

VMC prevailed when the pilot departed from Destin, Florida, U.S., for a positioning flight to Abbeville, Louisiana, the night of Aug. 2, 2016. The 414 climbed to about 900 ft over the Gulf of Mexico, entered a steep right turn, descended rapidly and struck the water in a nose-down attitude.

Examination of the recovered wreckage revealed no evidence of a pre-impact failure or malfunction. Investigators determined that the pilot likely lost control of the airplane due to spatial disorientation.

“Although the accident pilot was instrument-rated and had recently completed instrument currency training, the dark night conditions present at the time of the accident, combined with a further lack of visual references due to the airplane’s location over a large body of water, presented a situation conducive to the development of spatial disorientation,” the NTSB report said.

Cobbled Rudder Control Fails

Piper Seneca. Minor damage. No injuries.

The pilot was receiving instruction in recovering from flight at minimum control speed near Palm Coast, Florida, U.S., the afternoon of July 17, 2013, when both the pilot and his instructor felt two “kicks” in the rudder system, the NTSB report said. They confirmed to each other that neither had made any rudder-control inputs.

“The pilot receiving instruction then heard a ‘snap,’ and the rudder pedals began to ‘pump’ [with] full deflection right and left,” the report said. The flight instructor took control of the airplane and found that he could not stop the deflections either by using full rudder control or placing both feet on the rudder pedals. “Even with both pilots trying to neutralize the rudders, the deflections continued,” the report said.

The flight instructor landed the airplane at a nearby airport without further incident. Examination of the Seneca revealed that the uncommanded rudder deflections began when the rudder trim tab control rod fractured due to overload. Investigators found that the rudder trim control rod was made of lower-grade steel than specified and was not the correct part for the airplane. “It could not be determined when or by whom the rod was installed on the airplane,” the report said.

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Helicopters

Too Low to Attempt a Restart

Hughes 269C. Substantial damage. One fatality, one serious injury.

The helicopter was about 1,100 ft above the ground in Howe, Texas, U.S., the evening of Aug. 9, 2016, when the flight instructor reduced power to idle to initiate a practice autorotation. The engine subsequently lost power, and the instructor’s attempts to restart the engine were unsuccessful.

“The student provided conflicting statements regarding who was controlling the helicopter during the autorotation and landing but stated that he started the landing flare [at] about 25 ft AGL [above ground level],” the NTSB report said. The helicopter touched down hard and rolled onto its right side. The flight instructor was killed, and the student pilot was seriously injured.

The report said that the flight manual for the 269C says that the fuel boost pump should be activated before a practice autorotation. An examination of the helicopter showed that the fuel boost pump switch was in the “OFF” position. The manual also says that if a power loss occurs below 2,000 ft AGL, the pilot should conduct an autorotative landing and not attempt to restart the engine.

‘Momentary Lapse of Concentration’

Westland Gazelle. Destroyed. One minor injury.

The pilot told investigators that he was attempting to land in a confined area on the bank of a canal next to an inn in Abbeyshrule, Ireland, the evening of July 15, 2015, when he had a “momentary lapse of my concentration” while looking at an obstruction and allowed the helicopter to drift too close to the building.

The main rotor blades struck the building, which “caused the tail of the helicopter to swing rapidly towards the wall and collide with it,” said that report by the Air Accident Investigation Unit of Ireland. “The tail boom separated from the helicopter, broke apart and came to rest in the canal.” The Gazelle rolled right and struck the canal bank.

Neither the pilot nor his passenger was hurt, and they were able to exit from the helicopter through the broken cockpit canopy. However, one person inside the inn sustained minor injuries from debris. “It is the opinion of the investigation that the chosen location was inappropriate and wholly unsuitable for a helicopter landing,” the report said.

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