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.
Boeing 777-200, Boeing C-17 Globemaster. No damage. No injuries.
Incomplete and incorrect coordination among air traffic controllers was cited by the U.S. National Transportation Safety Board (NTSB) as the probable cause of a near midair collision between the 777 and the C-17 over the North Atlantic the night of Jan. 20, 2011.
In its final report on the incident, the NTSB said that noncompliance with established communications phraseology and incorrect data block displays were contributing factors when the airliner and the lead airplane in the flight of two U.S. Air Force C-17 transports came within 0.38 nm (0.70 km) of each other at the same altitude about 80 nm (148 km) southeast of New York.
The incident occurred at 2235 local time in visual meteorological conditions (VMC) on what was described as a dark night. The 777 was southeast-bound, en route from New York’s John F. Kennedy International Airport on a scheduled passenger flight to São Paulo, Brazil. The C-17s were west-bound, returning to Joint Base McGuire-Dix-Lakehurst in Wrightstown, New Jersey, after completing an aerial-refueling operation with a McDonnell Douglas KC-10. The lead C-17 was about 4,000 ft (1,219 m) ahead of the other transport and about 500 ft (152 m) left.
The airplanes were in the same sector of airspace governed by the New York Air Route Traffic Control Center but were being handled by two different radar controllers. One controller had cleared the 777 flight crew to climb to Flight Level (FL) 230 (approximately 23,000 ft); the other controller had cleared the lead C-17 flight crew to descend from FL 250 to 10,000 ft.
The controller handling the 777 was engaged in clarifying a route clearance with the crew of another airplane in the sector when he received a landline call from the center’s air traffic data controller, who was coordinating the activities of both the 777 controller and the C-17 controller. The 777 controller, focusing on a lengthy clearance readback by the other crew, told the coordinator that he would call back, but the coordinator proceeded to instruct the controller to stop the 777’s climb at FL 210. The 777 controller apparently did not hear that instruction.
“While still on an open line with that controller, the data controller [coordinator] leaned toward the controller working the two C-17s and told him to stop his flight at FL 220,” the report said. “The controller working the 777 overheard the portion of the communication where the [coordinator] said to stop at FL 220 and believed that the instruction was meant for the 777. Therefore, the controller instructed the 777 to climb to FL 220, while at the same time the [other] controller instructed the C-17s to descend to FL 220.”
New York Center’s radar data processing system generated a conflict alert about the same time the 777 crew received a traffic-alert and collision avoidance system (TCAS) resolution advisory to descend. The airplanes were about 7 nm (13 km) apart when the 777 crew reported that they were following a TCAS “descend” instruction. The report noted that the initial TCAS resolution advisory to descend was soon followed by an advisory to increase the descent rate and then by an advisory to climb, but the report did not provide details about the reversal or the crew’s response to the TCAS resolution advisories.
The C-17s also were equipped with TCAS, but the systems were configured to provide only traffic advisories.
“When the controllers noticed the conflict, they instructed both [the 777] and [the C-17s] to turn, in an unsuccessful attempt to maintain separation,” the report said. The 777 crew was instructed to turn left, and the C-17 crews were told to turn right.
The 777 crew also was advised that they had “traffic now one o’clock, four miles southwest, heavy C-17, Flight Level 220.” A few seconds later, the controller asked the 777 crew if they had the traffic in sight. The response was: “No, we do not.”
The crew of the lead C-17 was advised that the “traffic right below you is a Boeing triple-seven that should be leveling at Flight Level 210.” The C-17 crew replied, “Yeah, [we] just came within approximately 2,000 feet of that traffic.”
The 777 crew then radioed, “That guy passed us now, and that was not good.” The controller replied, “I understand that, and I apologize. I am not working that other airplane.”
Investigators found that when the near collision occurred, the data blocks on the controllers’ radar displays did not show the actual altitude assignments — that is, that the 777 and the C-17s had been cleared to FL 220. Instead, “the data block for the 777 indicated that the airplane was cleared to climb to FL 230, and the data block for the C-17s indicated that [they] were cleared to descend to 10,000 ft,” the report said. “Both of these were incorrect.”
Tail Strike During Go-Around
Airbus A321-211. Minor damage. No injuries.
The A321 was en route the evening of Dec. 23, 2011, from Austria with 182 passengers and six crewmembers to Manchester, England, which was reporting surface winds from 320 degrees at 16 to 27 kt, scattered clouds and light rain showers. The aircraft encountered turbulence as it descended through 1,500 ft above ground level (AGL) during the instrument landing system (ILS) approach to Manchester’s Runway 23R.
“The copilot [the pilot flying] disengaged the autothrust system as briefed, and, with turbulence increasing as the aircraft descended, the commander increased the approach speed target by 5 kt,” said the report by the U.K. Air Accidents Investigation Branch (AAIB). “Slightly below 1,000 ft, the copilot disengaged the autopilot.”
Aircraft control became increasingly difficult as the A321 descended below 400 ft, and the copilot had to make nearly continuous roll inputs, occasionally with full sidestick deflection. “By about 100 ft, the situation had become worse, and shortly afterwards, he initiated a go-around,” the report said, noting that recorded flight data showed a wind shear from a 4-kt tailwind component to an 8-kt headwind component.
The crew set TOGA (takeoff/go-around) thrust, and the copilot rotated the aircraft to a 10-degree nose-up pitch attitude. “Almost simultaneously, the crew sensed a severe downdraft which caused the aircraft to sink and the main gear to make contact with the runway,” the report said. Flight data showed that the 8-kt headwind component had sheared to an 8-kt tailwind component as the go-around was initiated.
The crew completed the go-around and then added 10 kt to the target airspeed for the second approach. The aircraft again encountered wind shear, which caused a 10- to 15-kt airspeed loss close to the runway, but the copilot landed the Airbus without further incident.
“During the commander’s external inspection after arriving on stand, he discovered damage to the lower rear fuselage skin and suspected that the aircraft had suffered a tail strike during the go-around manoeuvre,” the report said. “An engineering inspection confirmed that the aircraft would be unable to operate the return sector pending further maintenance action.”
Asleep at the Wheel
Boeing 737-700. Substantial damage. No injuries.
A snowplow operator was clearing snow from the ramp at Denver International Airport the afternoon of Dec. 22, 2011. He had been on duty for 6.5 hours after a six-hour rest break, during which he attempted to sleep in a vehicle following a previous shift from 1730 to 0200 local time. Investigators were unable to determine why he spent the rest period in the vehicle, rather than in the snow-removal company’s bunkhouse.
“Since the vehicle was being operated, he probably did not get uninterrupted sleep and, most likely, got less than six hours of sleep,” the NTSB report said. “The company did not have, and was not required to have, guidance or a policy addressing fatigue management.”
The snowplow operator told investigators that he fell asleep while driving behind the 737, which was being prepared for pushback from the gate. “The snowplow passed the airplane and then initiated a gradual turn to the right,” the report said. “The snowplow continued around 180 degrees and hit the airplane on the left side, near the empennage.”
The impact buckled the auxiliary power unit access door, pierced three 4-in (10-cm) holes in the fuselage skin and broke a stringer. The snowplow cabin also was damaged, but the operator was not hurt.
The report said that the snow-removal company’s “lack of a policy regarding employee fatigue” was a factor in the accident. The company told investigators that its snowplow operators typically worked 12- to 14-hour shifts and that “the responsibility for fatigue and fatigue management comes down to personal responsibility.
Incursion Prompts High-Speed RTO
Airbus A321-231, Boeing 737-800. No damage. No injuries.
Runway 16 was in use at Dublin (Ireland) Airport the afternoon of May 21, 2011, but the A321 flight crew requested, and received, clearance to use the longer runway, Runway 28, for departure. The Airbus was bound for Tenerife, Spain, with 152 passengers and six crewmembers.
As the A321 was taxied from the stand, the ground traffic controller instructed the crew to proceed via Taxiway E1 and hold short of Runway 28. Taxiway E1 leads to an intersection common to the approach end of Runway 28 and the departure end of Runway 16. Although a left turn and a right turn were required to reach the taxiway, the crew mistakenly continued taxiing straight ahead, onto Taxiway A, which is northwest of Taxiway E1.
Meanwhile, the ground controller had instructed the A321 crew to switch to the tower frequency and had diverted her attention to other aircraft. She did not see the A321 enter Taxiway A.
“As they approached the edge of Runway 16, the first officer, or pilot not flying (PNF) questioned their position, so [the commander] stopped the aircraft,” said the report by the Irish Air Accident Investigation Unit. The A321 came to a stop on the runway.
By this time, the tower controller had cleared the flight crew of the 737 to take off on Runway 16. The 737 was bound for Vilnius, Russia, with 145 passengers and six crewmembers. The crew initiated the takeoff as the A321 was taxied onto Taxiway A.
As the 737 accelerated through 80 kt, the commander saw the A321 taxiing toward the end of the runway, and she asked the first officer, “Where’s that guy going?” The first officer replied, “He’s taxiing out in front of us.” The commander called “stop” and initiated a high-speed rejected takeoff (RTO) just before the tower controller instructed the crew to discontinue the takeoff.
Indicated airspeed was 123 kt, or about 4 kt below V1, and the 737 was 820 m (2,690 ft) from the approach end of Runway 16, when the 737 commander applied the wheel brakes and reduced power to initiate the RTO. The Boeing came to a stop about 360 m (1,181 ft) from the Airbus, or about 1,455 m (4,774 ft) from the approach threshold of Runway 16. The 737 crew then taxied the aircraft back to the stand, where maintenance technicians examined the wheel brakes and released the aircraft for departure.
“When asked by investigators if she had carried out an actual RTO before, the  commander said she had not and added that ‘all the simulator training works,’” the report said.
The A321 pilots told investigators that the taxi route from the stand to the runway was short but complicated, and that bright sunlight reflecting off the wet taxiways had made the yellow markings difficult to see.
The report noted that a red stop bar on Taxiway A was used only during low-visibility conditions and, thus, was not illuminated when the incident occurred. Dublin Airport Authority made several changes as the result of the incident, including mandating 24-hour use of the stop bar, installing additional taxiway directional markings and publishing “hot-spot” information on the airport chart.
Braking Action Deteriorates
Gulfstream G200. No damage. No injuries.
TMU values range from 0 [to] 100, where 0 is the lowest friction value and 100 is the maximum friction value,” the NTSB report said. “A MU value of 40 or less is the level at which aircraft braking performance starts to deteriorate and directional control begins to be less responsive.”
The airplane’s departure from Bozeman, Montana, U.S., for a positioning flight to Jackson, Wyoming, the morning of Nov. 22, 2010, was delayed because of adverse weather conditions and reported runway surface friction (MU) values in the 20s at Jackson Hole Airport.
About an hour after the originally planned departure time, a company dispatcher released the G200 for the flight, telling the flight crew that the weather at Jackson had improved and that MU values were in the 40s.
The airplane was about 10 minutes from the destination when air traffic control (ATC) told the crew that the reported MU values on the beginning, middle and end of Runway 19 were 40, 42 and 40, respectively, with patchy thin snow over patchy thin packed snow and ice on the runway surface.
The crew conducted the ILS approach to Runway 19 in weather conditions that included surface winds from 180 degrees at 11 kt, 1/2 mi (800 m) visibility in light blowing snow, a broken ceiling at 500 ft and an overcast at 2,500 ft.
“The landing was made at a time when the runway conditions were deteriorating and the braking performance was becoming less effective,” the report said. “During the landing roll, thrust reversers were deployed, and the crew noted that all of the ground and air slat indication lights were green and that the anti-skid system began to pulse. … Despite the application of maximum thrust reverse, there was no effect on slowing the airplane, and it exited the departure end of the 6,300-ft [1,920-m] runway and came to rest just beyond the blast pad.”
The report noted that MU values were reported as 34, 33 and 23 about seven minutes after the G200’s overrun.
Jammed Door Blocks Gear
Fairchild Dornier SA 227-DC. Minor damage. No injuries.
Night VMC prevailed on Jan. 19, 2010, when the Metroliner, inbound from Brno, Czech Republic, with just the two pilots aboard, was established on final approach to Runway 07 at Stuttgart (Germany) Airport. When the crew attempted to extend the landing gear, they received an indication that the right main landing gear was not down and locked.
After cycling the landing gear and receiving the same indication, the crew initiated a go-around and tried several times to extend the landing gear using the emergency procedure. “All attempts were futile,” said the report by the German Federal Bureau of Aircraft Accident Investigation (BFU). “The indications for the right main landing gear remained red.”
The crew flew the Metroliner past the airport traffic control tower for a visual check by the controllers, who confirmed that the right main landing gear was not extended. The crew then was vectored to an area where they induced positive and negative loads on the aircraft in an attempt to unlock the right main gear. “After nine minutes, the attempts were aborted because they had been in vain,” the report said. “The crew declared an emergency and decided to land with the one remaining main landing gear and the nose landing gear.”
Both engines were shut down, the propellers were feathered, and the electrical system was disengaged before the aircraft touched down. “After the landing, as speed had been reduced and the right wing could no longer be kept in the air, the aircraft was steered toward the right and off the runway into the grass, so that the right wing could be rested on soft ground,” the report said. “After the aircraft had come to a complete stop, the crew left it by way of the passenger door.”
Investigators found that the outer clamshell door on the right main landing gear had jammed against the edge of the wheel well and had prevented the gear from extending. Pre-existing dents and rippling of the door skin were found, but the cause of this damage was not determined.
Fuel Planning Falls Short
Cessna 208 Caravan. Substantial damage. One minor injury.
The Caravan was refueled with 16 gal (61 L) of jet fuel, which the pilot deemed sufficient for two skydiving flights near Mesquite, Nevada, U.S., on Dec. 17, 2011. “During the second skydiving flight, he delayed releasing the skydivers due to traffic in the area,” the NTSB report said. “As he turned the airplane back toward the drop zone, the airplane’s engine experienced a total loss of power.”
The pilot signaled the skydivers to jump and attempted to land the powerless airplane on the runway. The Caravan touched down long, overran the runway and crossed a road before coming to a stop on a golf course.
The report said that the probable cause of the accident was “the pilot’s improper preflight planning, which resulted in a loss of engine power due to fuel exhaustion.”
Asymmetric Reverse Thrust
Dornier 328-100. Minor damage. No injuries.
Two pilots and three technical crewmembers were dispatched from Cairns, Queensland, Australia, to participate in a search-and-rescue mission at Horn Island the afternoon of Jan. 10, 2012. While conducting an NDB (nondirectional beacon) approach, the crew noted that they would have an 8-kt left crosswind on landing.
Shortly after touching down on the runway centerline, the first officer, the pilot flying, moved the power levers into ground idle, then into reverse. “The flight data recorder indicated that the reverse thrust was initially applied evenly,” said the report by the Australian Transport Safety Bureau.
However, when the first officer released back pressure on the power levers as the aircraft decelerated through 48 kt, the reduction of internal spring pressure moved the right lever into ground idle, but the left power lever remained in the reverse position. The resulting asymmetric thrust caused the Dornier to veer left, despite the first officer’s application of full right rudder.
“At the same time, the nosewheel weight-on-wheels sensor showed the nosewheel alternating between ground and air modes, resulting in the nosewheel steering not being operational,” the report said.
The first officer transferred control to the captain shortly before the aircraft veered off the left side of the runway. “The captain brought both power levers back into reverse thrust and recovered the aircraft back onto the runway,” the report said. “Following the incident, an engineering inspection found that the left power lever appeared not to spring as far forward as the right power lever when released from the reverse thrust position.
“Power lever split had been noted on other aircraft within the fleet; however, the operator did not consider that these presented a serviceability issue as the approved technique for bringing the power levers out of reverse thrust back to ground idle required a controlled input and not reliance on the release of spring tension alone.”
Loose Bolt Causes Gear Collapse
Mitsubishi MU-2B-20. Minor damage. No injuries.
The pilot heard a “pop” when he extended the landing gear on approach to Walterboro, South Carolina, U.S., the afternoon of Jan. 16, 2011. “During the landing roll, the nose gear collapsed, resulting in minor damage to the nose gear doors and the skin behind the nose gear area,” the NTSB report said. The pilot and his passenger were not hurt.
Examination of the MU-2 revealed that the bolt holding the downlock drag brace joint link to the airframe was loose and had fractured when the nose gear was extended. The report said that the nose gear rigging had not been adequately checked, as required, during the last maintenance inspection of the airplane.
Mountain Shrouded by Clouds
Piper Navajo. Destroyed. Two fatalities.
Having recently retired from airline operations, the pilot departed from Welshpool (Wales, U.K.) Airport the morning of Jan. 18, 2012, to refamiliarize himself with the Navajo in preparation to fly part-time in business operations. VMC prevailed at the airport, but low broken clouds shrouded the tops of local mountains.
Another pilot familiar with the aircraft and the area accompanied the pilot. They initially flew south for some distance and then returned to land. The pilot flew over the runway, established the aircraft on upwind, crosswind and then left downwind for Runway 22. He flew a wider-than-normal downwind leg, likely to provide clearance from a helicopter ahead on downwind, said the AAIB report.
The report said that the pilots might have thought they were clear of high terrain north of the airport when they began a wide left base and inadvertently descended into clouds. The Navajo struck the tops of trees and crashed in a field on the upper slope of a mountain about 2 nm (4 km) northeast of the airport.
Takeoff on an Empty Tank
Cessna U206G. Substantial damage. One serious injury, three minor injuries.
The single-engine airplane was departing from Matinicus Island, Maine, U.S., for a charter flight to Rockland the afternoon of July 17, 2011, when the engine began to lose power about 200 ft above the ocean. The pilot “immediately advanced the throttle and turned on the auxiliary fuel pump, with no results,” the NTSB report said.
The airplane sank after it was ditched, but the pilot and his three passengers, one of whom was seriously injured on impact, clung to the separated cargo pod for about one hour until they were rescued by the crew of a fishing boat.
The passengers had not received a preflight briefing. “If a piece of wreckage had not been available for the passengers to hold on to, the failure of the pilot to notify the passengers of the availability of life vests could have increased the severity of the accident,” the report said.
Examination of the recovered wreckage showed that the fuel selector was positioned to the right tank, which held about 1 pint (1/4 L) of fuel and 25 gal (95 L) of seawater. The left tank held about 27 gal (102 L) of fuel and 2 gal (8 L) of seawater. The report said that the probable cause of the accident was “the pilot’s improper fuel management, which resulted in a total loss of engine power due to fuel starvation.”
Pressing Ahead in IMC
Piper Twin Comanche. Destroyed. Two fatalities.
The pilot had filed a composite visual/instrument flight rules flight plan from Lucques, Italy, to Troyes, France, but, en route at 2,000 ft the morning of June 17, 2011, he asked a controller at Nice Flight Information Service if he could transition to instrument flight rules earlier than planned. “The controller responded that it was not possible to comply with this request,” said the report by the French Bureau d’Enquêtes et d’Analyses (BEA).
The controller then asked the pilot to navigate via two waypoints that took the Twin Comanche north of the flight-planned route. The pilot complied with the request while continuing under visual flight rules (VFR).
The aircraft was registered in England, and U.K. representatives who participated in the investigation commented that the controller’s request did not comply with standard ATC phraseology and might have been interpreted by the pilot as an instrument flight rules clearance.
About eight minutes after making the request, the controller told the pilot that he had lost radar contact with the aircraft. The pilot acknowledged the advisory about two minutes before the Twin Comanche struck rising terrain at 2,700 ft, killing the pilot and his passenger.
The BEA report concluded that “the accident was due to the pilot’s decision to continue the flight under VFR in instrument meteorological conditions [IMC] and at an altitude that was lower than the high ground in the region.”
Ice Ingestion Causes Flameout
MD Helicopters MD-600N. Destroyed. Two serious injuries, one minor injury.
The flight crew was inspecting the roofs of buildings in central Germany for snow damage and landed the helicopter on a street in Jena to board an employee of a building-supplies store the afternoon of Dec. 28, 2010. “Witnesses observed a big snow cloud being raised by the helicopter and it hovering for a long period of time above the snow cloud before it finally landed,” said the BFU report.
During the subsequent lift-off, the helicopter again raised a large amount of snow and was transitioning to forward flight at about 100 ft AGL when the engine flamed out. Both pilots were seriously injured and the passenger sustained minor injuries when the MD-600 descended rapidly to the street.
The report concluded that “the accident occurred due to a sudden engine failure shortly after takeoff caused by the ingestion of ice at a height and with a speed not sufficient for autorotation.”
Wire Strike Over Highway
Hughes 369D. Substantial damage. No injuries.
Before departing on a positioning flight from Knoxville, Tennessee, U.S., the afternoon of Dec. 21, 2011, the pilot determined that VMC prevailed at Knoxville and at the destination, Blountville, also in Tennessee.
“However, while the pilot was following a highway in cruise flight at 400 ft AGL, the ceiling rapidly became lower, and the pilot encountered IMC,” the NTSB report said. “Moments later, while cruising at an airspeed of 65 kt, the pilot saw marker balls, which indicated that power lines were directly in front of the helicopter.”
The pilot began a right, diving turn in an attempt to avoid the power lines, but a main rotor blade struck a wire. “The rotor speed remained within limits, but the helicopter began to vibrate, so the pilot decided to land in a nearby field,” the report said. Examination of the helicopter revealed substantial damage to the rotor blade.
Settling With Power
Robinson R44. Destroyed. Two fatalities.
The pilot was circling at low altitude and waving at people on the ground when the R44 descended and struck terrain near Centerville, Louisiana, U.S., the morning of Jan. 19, 2012. The pilot and his passenger were killed.
“Examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation,” the NTSB report said. “Impact signatures were consistent with the engine developing power at impact, and it is likely that … the helicopter was in a steep descent consistent with settling with power.