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 737-700. Minor damage. No injuries.
The flight crew had completed a leg from Chicago to Denver the morning of April 26, 2011, and were returning early that afternoon to Chicago Midway International Airport. Nearing Midway, the crew was told by an approach controller to expect to hold due to delays caused by weather and traffic on the approaches to Midway and nearby O’Hare International Airport.
“Shortly afterward, the controller advised the crew that aircraft capable of conducting the required navigation performance (RNP) area navigation [RNAV] approach to Runway 13C would be accepted to [land at Midway],” said the U.S. National Transportation Safety Board (NTSB) report. The controller said that a 30-minute hold could be expected before being sequenced for the RNP approach, while an indefinite hold could be expected for all other approaches.
The crew told the controller that they were “RNP capable,” but then mistakenly briefed and programmed the 737’s flight management system (FMS) for the global positioning system (GPS) approach rather than the RNP RNAV approach to Runway 13C, the report said.
After entering the holding pattern, the crew received the latest weather information for Midway and used the on-board performance computer (OPC) to conduct a landing distance assessment for Runway 13C. They also reviewed their fuel status and options for diverting to an alternate airport.
A line of thunderstorms had passed over Midway about 10 minutes earlier. The automatic terminal information service (ATIS), based on an observation taken five minutes earlier, said in part that surface winds were from 190 degrees at 16 kt, gusting to 23 kt; visibility was 6 mi (10 km) in light rain and mist; and the clouds were scattered at 800 ft, broken at 1,400 ft and overcast at 2,200 ft.
The crew’s landing distance assessment was based on OPC inputs that included an estimated landing weight of 126,000 lb (57,154 kg) and the use of speed brakes, reverse thrust and maximum autobraking to land on a wet runway with good braking action reported. The result was a calculated “stop margin” of 720 ft (219 m). “Stop margin is the distance remaining after the aircraft comes to a complete stop, measured from the nose gear to the end of the runway,” said the report, noting that the calculation is based on certain assumptions, such as touching down 1,500 ft (457 m) beyond the approach end of the runway, and includes a 15 percent safety factor.
Runway 13C had an available landing distance of 6,059 ft (1,847 m). “The calculation results showed sufficient runway length for the landing, in accordance with the flight manual procedures,” the report said.
After holding for about 27 minutes, the crew was cleared by air traffic control (ATC) to proceed to the Joliet VHF omnidirectional radio (VOR) and to intercept the initial approach course. Although they acknowledged the clearance, the crew was confused because the VOR was not on the GPS approach procedure that they had briefed and programmed into the FMS. The report said that the ensuing discussion between the pilots, their identification and briefing of the correct procedure, and their reprogramming of the FMS for the RNP approach were distracting and added to their workload.
Additional distractions during the approach included a flap-overspeed warning when the first officer attempted to set flaps 25 at an airspeed above the limit and a discussion of the direction of movement of a rain shower near the threshold of Runway 13C.
The crew also heard a radio transmission by a pilot in a preceding Cessna Citation that braking action while landing on the runway was “fair.” Based on this report, the 737 crew again used the OPC for a landing distance assessment with fair braking action. This resulted in a calculated stop margin of 210 ft (64 m), which also met requirements.
The cockpit voice recording indicated that the crew did not conduct the “Before Landing” checklist or mention the speed brakes. Recorded flight data indicated that the speed brakes were not armed to deploy automatically on touchdown, as required by the checklist. “A lack of speed brake deployment results in severely degraded stopping ability,” the report said. “According to the [airline’s] flight operations manual, braking effectiveness is reduced by as much as 60 percent.”
Shortly after the 737 touched down within 500 ft (152 m) of the runway threshold, the captain perceived that deceleration was inadequate and applied full manual braking, which disengaged the autobrakes. Neither pilot noticed that the speed brakes had not deployed.
“About 16 seconds after touchdown, thrust reversers were manually deployed, which also resulted in speed brake deployment per system design, when the airplane had about 1,500 ft [457 m] of runway remaining,” the report said. “As the airplane neared the end of the runway, the captain attempted to turn onto the connecting taxiway but was unable. The airplane struck a taxiway light and rolled about 200 ft [61 m] into the grass.”
The 737 came to a stop about 180 ft (55 m) from the runway threshold and to the left of the engineered materials arresting system. None of the 134 passengers or five crewmembers was injured. “The right engine sustained damage from ingesting a taxiway light, and the thrust reverser and inlet cowls were damaged,” the report said. “Two fan blades of the left engine were bent. The left and right inboard aft flaps were damaged. The damage did not meet the [NTSB] definition of ‘substantial.’” Thus, the event was categorized as an incident, rather than an accident.
The NTSB determined that the probable cause of the incident was “the flight crew’s delayed deployment of the speed brakes and thrust reversers, resulting in insufficient runway remaining to bring the airplane to a stop.”
Performance studies indicated that, under the existing conditions, the airplane likely would have stopped with about 900 ft (274 m) of runway remaining if the speed brakes had deployed automatically on touchdown, or with about 1,950 ft (594 m) of runway remaining if both the speed brakes and thrust reversers had deployed promptly.
Anomalies Traced to Generator
Airbus A321-231. No damage. No injuries.
The A321 began to experience electrical system anomalies while cruising in instrument meteorological conditions and light turbulence at Flight Level (FL) 360 (approximately 36,000 ft) over northern Sudan during a scheduled flight from Khartoum to Beirut, Lebanon, with 42 passengers and seven crewmembers the night of Aug. 24, 2010.
“The commander [the pilot flying] reported that, without warning, his primary flight display (PFD), navigation display (ND) and the ECAM [electronic centralized aircraft monitor] upper display unit (DU) began to flicker, grey out, show lines or crosses, and go blank,” said the report by the U.K. Air Accidents Investigation Branch (AAIB). At the same time, the flight crew heard a “chattering” sound emanating from the circuit breaker panels behind their seats.
The anomalies initially lasted only briefly. The copilot checked the circuit breaker panels but found none of the circuit breakers open and no signs of overheating. “The commander reviewed the ECAM electrical system page, which showed no abnormalities,” the report said.
Shortly thereafter, the anomalies affecting the commander’s PFD and ND, and the upper ECAM DU resumed, and the cockpit lights began to flicker. The crew disengaged the autopilot, and the commander transferred flight control to the copilot, whose displays initially functioned normally but then began to flicker. The chattering sound from the circuit breaker panels also resumed.
Numerous ECAM messages and master warnings appeared, and the A321’s digital electronic flight control system reverted to alternate law, which provides fewer automatic protections against exceeding specific flight envelope parameters.
In addition, “the aircraft rolled to the left and adopted an approximately 10-degree left-wing-low attitude, without any flight control input from the crew,” the report said. “The flight crew reported that the aircraft did not seem to respond as expected to their control inputs and shuddered and jolted repeatedly. … The ECAM was only sometimes visible and did not identify the root cause of the problem. [The pilots] were not aware of any procedure applicable to the symptoms experienced.”
The commander saw an “ELEC GEN 1 FAULT” message, and the associated checklist items appeared momentarily on the ECAM. He responded by disengaging the no. 1 integrated drive generator and activating the auxiliary power unit. “On doing so, the juddering motion ceased, the chattering noise stopped, and all displays reverted to normal operation, although the aircraft’s left-wing-low attitude persisted,” the report said.
Although the crew had made no trim changes, they noticed that the rudder trim display was several units left of neutral. “When the rudder trim was reset to neutral, the aircraft readopted a wings-level attitude,” the report said. “The aircraft had deviated approximately 20 nm [37 km] to the left of the intended track during the incident.”
The pilots hand flew the aircraft and landed in Beirut without further incident. The no. 1 integrated drive generator was replaced, and no similar anomalies occurred on subsequent flights. Although this indicates that the anomalies likely had resulted from a generator fault, the report said that “it was not possible to determine with any degree of certainty the cause of this incident.”
The commander had verbally reported the incident to the airline and had filed an air safety report, but the airline had not informed the AAIB of the incident until several weeks later. By that time, flight data recorded during the incident had been overwritten. “The operator stated that it had since taken actions to improve its processes for the reporting and tracking of air safety incidents,” the report said.
Early Flare Cited in Overrun
Boeing 737-400. Minor damage. No injuries.
The ATIS at Amsterdam (Netherlands) Schiphol Airport the night of Oct. 2, 2010, indicated that the surface winds were variable at 9 kt, visibility was 2,500 m (about 1 1/2 mi) in rain and there were a few clouds at 400 ft, scattered clouds at 700 ft and a broken ceiling at 1,100 ft.
Inbound from Dalaman, Turkey, on a scheduled flight with 167 passengers and six crewmembers, the flight crew had prepared for an approach to Schiphol’s Runway 18R. “Due to the changing weather conditions, ATC changed the runway for landing to Runway 22” when the 737 was about 15 minutes from the airport, said the report by the Dutch Safety Board.
The report said that the crew had calculated a reference landing speed of 140 kt for Runway 18R and “did not change the reference landing speed for Runway 22,” which, at 2,014 m (6,608 ft), is about 1,786 m (5,860 ft) shorter than Runway 18R.
The crew conducted a stabilized instrument landing system approach to Runway 22, but heavy rain reduced their visibility during the final stage of the approach, the report said. The captain disengaged the autopilot 200 ft above ground level (AGL) and began to flare the aircraft early, at a radio altitude of about 50 ft, rather than at the normal height of 20 ft.
“Because of this pitch manoeuvre, the aircraft’s rate of descent decreased, and this resulted in a touchdown further down the runway,” the report said. “It also gave the crew the feeling that the aircraft was floating over the runway.”
Recorded flight data indicated that the wind was from 110 degrees at 6 kt, resulting in a slight tail wind as the 737 touched down about 860 m (2,822 ft) from the approach threshold of the runway.
The thrust reversers were deployed shortly after touchdown, and maximum brake pressure was applied. However, “the flight data showed that the speed brake handle did not reach full deflection and, as a consequence, the landing distance increased,” the report said. “The partial deployment could not be explained with the information available.”
The 737 came to a stop with the nose landing gear mired in soft ground about 9 m (30 ft) off the end of the runway. There were no injuries and only minor damage to the aircraft’s nosewheel.
Jet Blast Topples Occupied Push Stairs
Boeing 737-800. No damage. One serious injury.
The flight crew was preparing the 737 for a flight from Brisbane, Queensland, Australia, to Denpasar, Indonesia, the morning of Oct. 14, 2011. The first officer calculated the fuel requirements for the flight and then began to exit the 737 via the rear left cabin door to give the calculation to the refueling supervisor on the apron.
Meanwhile, a 747-400 was holding on a taxiway perpendicular to the 737’s gate area. The 737 first officer had stepped onto push stairs placed outside the rear left door when the 747 flight crew received instructions from ATC to continue taxiing and applied power to initiate forward movement, said the report by the Australian Transport Safety Bureau (ATSB).
The exhaust (jet blast) from the 747’s engines toppled the push stairs. “The first officer standing on the stairs fell to the tarmac, sustaining serious injuries,” the report said.
The tail of the 747 was about 71 m (233 ft) from the tail of the 737 when the accident occurred. The push stairs encountered a jet blast velocity of about 30 kt when the 747 crew applied breakaway thrust. “The stairs had been tested at manufacture and demonstrated stability at up to 50-kt wind speeds with locking pads applied,” the report said. “The investigation was not able to establish if the locking pads on the stairs were correctly applied at the time of the accident.”
Undrained Water Disrupts Power
Beech King Air 200. Destroyed. Five fatalities, one serious injury.
Surface winds were from 200 degrees at 3 kt, visibility was 10 mi (16 km), and there was an overcast at 800 ft when the pilot initiated a departure from Runway 30 at Long Beach (California, U.S.) Airport for a business flight the morning of March 16, 2011. Witnesses told investigators that the King Air stopped climbing and yawed left shortly after liftoff. They heard noises similar to propeller-blade pitch changes and saw smoke trailing the airplane.
“A witness, who was an aviation mechanic with extensive experience working on airplanes of the same make and model as the accident airplane, reported hearing two loud ‘pops’ about the time the smoke appeared, which he believed were generated by one of the engines intermittently relighting and extinguishing,” the NTSB report said.
The King Air entered a left skid with a bank angle between 45 and 90 degrees and then descended in a near-vertical attitude. “Just before impact, the airplane’s bank angle and pitch began to flatten out,” the report said. “The airplane had turned left about 100 degrees when it impacted the ground about 1,500 ft [457 m] from the midpoint of the 10,000-ft [3,048-m] runway. A fire then erupted, which consumed the fuselage.” The pilot and four passengers were killed, and one passenger was seriously injured.
Examination of the wreckage revealed no pre-existing anomalies. The nacelle tanks, from which fuel is fed to the engines, had been breached on impact, and no fuel remained in them. Tests of fuel samples taken from the refueling truck showed no sign of contamination. However, investigators concluded that the left engine’s momentary power disruptions during takeoff had been caused by water that had not been drained from the fuel tanks during the pilot’s preflight preparations.
The King Air 200 operating manual states that fuel should be drained from the 12 sumps before every flight. “The investigation revealed that the pilot’s previous employer [a U.S. Federal Aviation Regulations Part 135 charter operator], where he had acquired most of his King Air 200 flight experience, did not have its pilots drain the fuel tank sumps before every flight,” the report said. “Instead, maintenance personnel drained the sumps at some unknown interval.”
The pilot, 43, who had logged 1,113 of his 2,073 flight hours in multiengine airplanes, including 463 hours in type, had been employed as a contract pilot for the past 10 months. “He had been the only pilot of the [accident] airplane for its previous 40 flights,” the report said. “Because the airplane was not on a Part 135 certificate or a continuous maintenance program, it is unlikely that a mechanic was routinely draining the airplane’s fuel sumps.”
NTSB concluded that the probable cause of the accident was “the pilot’s failure to maintain directional control of the airplane during a momentary interruption of power from the left engine during the initial takeoff climb.”
“Given that the airplane’s airspeed was more than 40 kt above the minimum control speed of 86 kt when the left yaw began, the pilot should have been able to maintain directional control during the momentary power interruption,” the report said, noting that this applied despite the airplane being about 650 lb (295 kg) over maximum takeoff weight when the accident occurred.
The pilot had completed a Part 135 pilot-in-command check flight in a King Air five months before the accident. “However, no documentation was found indicating that he had ever received training in a full-motion King Air simulator,” the report said. “Although simulator training was not required, if the pilot had received this type of training, it is likely that he would have been better prepared to maintain directional control in response to the left yaw from asymmetrical power.”
Split Seal Causes Depressurization
Bombardier Q400. Minor damage. No injuries.
En route from Manchester, England, with 49 passengers and four crewmembers, the aircraft was descending from FL 250 to FL 200, in preparation to land in Brussels, Belgium, the morning of Oct. 12, 2011, when the flight crew felt mild inner ear pain and saw indications of cabin depressurization. Cabin altitude was increasing in excess of 3,000 fpm.
“The cabin crew reported by interphone that a loud ‘pop’ had been heard from the rear of the aircraft, followed by the noise of air escaping from the rear left galley area,” the AAIB report said.
The cabin pressure warning light illuminated, and both pilots donned their oxygen masks. The commander, the pilot flying, initiated an emergency descent, and the first officer declared an emergency with ATC.
The commander stopped the descent at FL 80. “After establishing with the cabin crew that the passengers were not in difficulty and observing that the cabin pressurisation system had stabilized the cabin altitude at 2,000 ft, the commander … decided to continue the fight to Brussels Airport, where the aircraft landed without further incident,” the report said.
Maintenance personnel found that the inflatable seal on the aft baggage compartment door had split, causing the compartment to depressurize. “This had caused the ‘blow-out’ panels on the bulkhead dividing the aft baggage compartment from the passenger cabin to open, causing the ‘pop’ noise, and the open blow-out panels then allowed the passenger cabin to depressurize,” the report said.
‘Inadequate Skill’ Led to Overrun
Cessna 208B Caravan. Substantial damage. No injuries.
nbound from Imphal, India, on a charter flight to Lengpui with nine passengers the morning of May 4, 2011, the pilot was told by ATC that visibility at the destination was 4,500 m (about 2 3/4 mi). The pilot requested and received a special visual flight rules clearance into Lengpui’s airspace.
Visibility then decreased to 2,000 m (1 1/4 mi), and ATC approved the pilot’s request to enter a holding pattern at 6,500 ft. “The pilot thereafter, without any communication with ATC, reported downwind for Runway 17 and subsequently reported for final,” said the report by the Indian Directorate General of Civil Aviation (DGCA). “The controller, after sighting the aircraft, gave the landing clearance, with wind as calm and runway surface wet.”
The report said that “it was impossible to stop the aircraft” after it touched down “well beyond” the threshold of the 2,500-m (8,203-ft) runway at high speed. The Caravan overran the runway and descended into a 60-ft (18-m) ravine.
Investigators found that the pilot, who had 1,983 flight hours, had not accumulated the 100 hours as pilot-in-command in type required to conduct single-pilot charter operations and did not meet requirements for operating at airports in mountainous terrain. The DGCA concluded that the cause of the accident was the “inadequate skill level of the pilot to execute a safe landing during marginal weather conditions.”
Water Favored Over Airport
Piper Chieftain. Destroyed. No injuries.
The Chieftain was en route at 9,000 ft from Punta Cana, Dominican Republic, to Aguadilla, Puerto Rico, the afternoon of Oct. 27, 2010, when the pilot noticed high cylinder head and oil temperatures, and a partial loss of power from the right engine. The pilot received clearance from ATC to descend to 2,500 ft and to divert the flight to Borinquen Airport in Puerto Rico.
“Both engines were operating; however, the loss of rpm on the right engine made it hard to maintain altitude,” the NTSB report said. “[The pilot] shut down the right engine before performing the troubleshooting items listed in the POH [pilot’s operating handbook] and continued flying the airplane at 108 kt. He did not declare an emergency.”
The Chieftain was at 2,500 ft and about 4 nm (7 km) from Borinquen Airport when the pilot told the tower controller that he was going to ditch the airplane in the ocean. “When asked why he elected to ditch the airplane instead of continuing to the airport, the pilot stated [that it was] because of poor single-engine performance and windy conditions,” the report said, noting that the surface winds at the airport were from 060 degrees at 6 kt.
The pilot was rescued by a Coast Guard helicopter crew after he ditched the airplane about 3 nm (6 km) east of the airport. The Chieftain sank and was not recovered. NTSB concluded that the pilot’s decision to ditch the airplane was “improper.”
Power Loss Traced to O-Rings
Cessna 402B. Substantial damage. One fatality.
The 402 was on a positioning flight to Portland, Maine, U.S., the evening of April 10, 2011, when the pilot requested and received clearance from ATC to divert the flight to Biddeford, Maine. He gave no reason for the destination change, the NTSB report said.
Investigators determined that a partial loss of power from the right engine occurred on final approach, and the pilot intentionally reduced power from the left engine to prevent the airplane from rolling right. Minimum control speed with one engine inoperative is 82 kt; ATC radar data indicated that the airplane’s groundspeed decreased to 69 kt. The Chieftain descended, struck several trees at 25 ft AGL and came to rest on the roof of a house about 1,500 ft (457 m) from the runway.
Investigators determined that the partial power loss had been caused by improper installation of two O-rings in the right engine’s throttle-control assembly. When the O-rings were replaced, “the engine operated smoothly with no noted anomalies,” the report said.
Control Lost on Circling Approach
Piper Aerostar 601P. Substantial damage. No injuries.
When the Aerostar reached the missed approach point during a GPS approach to Castroville (Texas, U.S.) Municipal Airport on March 24, 2012, the pilot had the runway in sight but determined that the airplane was not in position for a normal landing. “He then decided to circle to land with full flaps, while maintaining an airspeed of 140 mph,” the NTSB report said.
The airplane entered a high sink rate during the turn to final. “The pilot added full power and leveled the wings, but the airplane continued to descend,” the report said. “The airplane impacted the ground off the end of, and to the right of, the runway.” The left wing spar was substantially damaged. The three people aboard the Aerostar were not injured.
Blinded by Landing Light
Bell 47G. Substantial damage. One serious injury.
Visibility was 2 1/2 mi (4,000 m) in mist, and there was a 100-ft overcast when the pilot departed from Salinas (California, U.S.) Municipal Airport the morning of Sept. 3, 2010, on a positioning flight to a nearby work site. The helicopter entered fog when the pilot climbed from 50 ft to 80 ft AGL to avoid power lines.
“The pilot stated that after entering the fog, he turned on the landing light, which blinded him and caused him to become disoriented as he attempted to make a 180-degree turn back to the airport,” the NTSB report said.
The pilot lost control, and the helicopter struck a guardrail and crashed inverted on the highway. “A truck driver who witnessed the accident reported that the forward visibility was about 250 ft [76 m],” the report said.
Water Causes Gearbox Corrosion
Robinson R44 Raven. Substantial damage. No injuries.
About 30 minutes after departing from Darwin for a charter flight to Bamurru Plains, both in Australia’s Northern Territory, the afternoon of July 28, 2011, the helicopter was descending through 650 ft when the pilot felt a minor but persistent vibration. About 30 seconds later, the vibration increased, and the pilot heard a loud “bang” and saw the clutch warning light illuminate.
“The pilot immediately conducted an autorotative descent and landing, resulting in distortion of the skids and minor damage to the tail boom from contact with a main rotor blade,” the ATSB report said. The four people aboard the R44 escaped injury.
Investigators determined that water had entered the main rotor gearbox gear carrier, causing it to corrode over time and fail from fatigue cracking during the accident flight. The gearbox failure caused the loss of main rotor drive.
Methane Chokes Engine
Bell 206L-3 LongRanger. Substantial damage. Three minor injuries.
Shortly after lifting off from a platform in the Gulf of Mexico the afternoon of March 24, 2011, the pilot heard a loud bang, lowered the helicopter’s nose and entered an autorotation.
“As the helicopter descended, the pilot activated the helicopter’s float system,” the NTSB report said. “The floats inflated; however, the helicopter impacted the water and rolled inverted.” The pilot and two passengers exited the helicopter and were rescued by a boat crew.
Examination of the engine revealed nothing that would have precluded normal operation, but recorded engine data indicated that a rapid and momentary increase in turbine outlet temperature and torque had occurred during the takeoff. Investigators determined that a compressor stall had occurred when the engine ingested methane that was being vented from the offshore platform.