Skyward International Aviation Fokker 50, Nairobi, 2 July 2014

Kenyan investigators report the crew of a cargo flight (5Y-CET) continued a night take-off despite multiple warnings of engine problems and crashed some 50s after becoming airborne. The report said the crew of the Skyward International Aviation Fokker 50 departing Nairobi’s main international airport for Mogadishu, Somalia, would have heard 27 triple-chime alerts beginning just 8s after the take-off was initiated. But although the turboprop was well below the V1 decision speed, the crew did not abort the take-off. Flight-data recorder information indicates the left-hand Pratt & Whitney Canada PW125 engine showed increasing torque but declining propeller speed compared with the right-hand engine. The Kenyan investigator reported the aircraft lifted off from the high-elevation airport at about 100kt (185km/h) but was “barely climbing”, reaching no more than 50ft above the ground after about 20s while continually turning left off the extended centreline. The aircraft subsequently collided with a building 2,100m (6,890ft) north-north-east of the runway end, killing all four crew on board. Investigators also found that the aircraft was loaded more than 500kg (1,100lb) above its maximum take-off weight. Analysis of recordings from the previous positioning flight by the aircraft showed a “three-chime” alert had occurred, and that the crew spent time trying to diagnose the problem, but investigators could not find any evidence of it in the technical log, nor that any rectification was conducted. The captain, the pilot flying, had logged over 6,800h in command of Fokker 50s, but the inquiry says it was “unable to determine” whether either pilot had received valid training in flying with one engine inoperative. Although the accident occurred in 2014, the inquiry was only signed off at the end of November 2019 and published by the transport ministry in January.

ACT Airlines Boeing 747-400, Bishkek, Kyrgyzstan, 16 January 2017

Investigators have shed more light on why the freighter (TC-MCL), crashed at Bishkek airport, Kyrgyzstan, was far too high early in its approach to the airport, leading to the aircraft capturing a false glideslope signal on final approach. The inquiry into the night-time accident had already established that the ACT Airlines Boeing 747-400 had been too high when nearing its final approach, leaving it susceptible to encountering the false glideslope while aiming to intercept the instrument landing system (ILS) for runway 26. During its early descent, the aircraft had been at 18,000ft over waypoint RAXAT, and was cleared to cross waypoint TOPKA at 6,000ft, but these two waypoints were just 27nm (50km) apart and the airline’s standard descent procedure would only have enabled the 747 to lose 9,000ft, whereas it needed to descend 12,000ft to reach 6,000ft by TOPKA. “They left us high again,” the captain remarked, one of several comments indicating the crew had been hoping for earlier clearances to a lower altitude. The aircraft was operating in “flight level change” mode and the crew selected 6,000ft with an airspeed of 262kt. Despite the requirement for a more aggressive loss of altitude, the inquiry says the initial descent was conducted without the use of speed brakes. Some 1min 40s into the descent the crew changed to “vertical speed” mode and increased the descent rate to 2,400ft/min (12m/s). The airspeed continued to rise, reaching a maximum of 317kt. Speed brakes were deployed manually at 12,200ft – initially to 30° and then to 36° – and the “flight level change” mode was re-engaged. The aircraft continued to descend but had reached only 9,200ft by the time it passed TOPKA. It was also travelling at 270kt, 20kt above the 250kt limit set in ACT standard operating procedures for flight below 10,000ft. “The chart requirements [for passing TOPKA] were not formally violated,” says the inquiry, “but the aircraft was too high to continue the approach in accordance with the chart” without additional manoeuvring to lose height. As it was, the aircraft remained above the approach profile, and inadvertently captured a false 9° glideslope from the ILS to runway 26. Owing to the very steep descent, it arrived over the airport too high and fast and landed beyond the runway end in a residential area, resulting in the loss of all four crew members, as well as 35 fatalities on the ground.

Indonesia AirAsia Airbus A320, Perth, 24 November 2017

The pilot of the Indonesia AirAsia Airbus A320 (PK-AZE), preparing for departure from Perth, Australia for Denpasar, Indonesia, assumed the departure runway would be the same as the arrival runway (03) and entered the wrong data into the flight management guidance system (FMGS). The Australian Transport Safety Bureau (ATSB) reports that the first officer – the pilot flying – had not listened to the automatic terminal information service (ATIS) until after he had entered the data for runway 03. Later, having heard that the runway in use was 21, he failed to correct the FMGS. The report notes that the captain had not listened to the ATIS either. As a result, after take-off from runway 21 as directed by air traffic control (ATC), the aircraft made a low left turn, and deviated from the cleared flightpath. The ATSB states: “Despite the various cues available to the flightcrew, including several ATC instructions for using runway 21, airport signage, and the flightcrew reporting feelings of unease about the flight preparations, the incorrect programming of the FMGS was not detected.” So shortly after taking off from runway 21, the aircraft flight director indicated a left turn, as the next programmed waypoint was behind the aircraft and in the opposite direction. Perth ATC noticed the deviation and corrected the crew’s heading several times. The aircraft, carrying 145 passengers and six crew, finally intercepted its flight-planned track and continued to Denpasar without further incident.

AirAsia A320 PK-AZE

Source: Wikimedia Commons/SabungDOThamster

Australian regulator found that Indonesia AirAsia A320 departed Perth on the wrong heading after a data entry error made by flightcrew

Air Astana Embraer 190, Alverca do Ribatejo, Portugal, 11 November 2018 

Portuguese engineering company OGMA has challenged accident investigator GPIAAF’s findings after a serious incident following major maintenance. The Air Astana Embraer 190 departed Alverca do Ribatejo air base bound for Minsk and Almaty with cross-rigged aileron cables, almost leading to the loss of the jet. The cross-rigging of the ailerons made it difficult to control the aircraft in roll. At one point, the pilots sought to head for the sea to ditch before they managed to regain a degree of control. The inquiry determined the improper aileron cable installation to be the probable cause of the incident, identifying a lack of an effective safety management system at OGMA. The E190’s aileron cables had been replaced, but testing was delayed and personnel without relevant experience, who found the maintenance instructions difficult to follow, connected the new cables. GPIAAF states that the crossover error went undetected during subsequent troubleshooting and testing. OGMA cites “weaknesses” in the aircraft’s design – which made it easy for the cables to be inverted – and flaws in the presentation of the cable routing in maintenance publications. It also points out that the pilots had not detected the improper aileron functioning during pre-flight checks, which they should have done. OGMA’s complaint is that it is singled out as the only agency at fault. OGMA claims the report makes too much of the fact that it has not completed its implementation of a safety management system, noting that this requirement is still subject to a rulemaking process that is unlikely to be mandated until around 2022-2023. It also argues that a maintenance release to service is “not a certificate” for the aircraft’s airworthiness, and that the operator is responsible for ensuring the aircraft is in flying condition – with the crew briefed to be particularly alert given that the jet had just come out of heavy maintenance. GPIAAF says its task is not to assign blame or liability, but has included OGMA’s comments to “ensure transparency”.

China Airlines Boeing 747-400F, Taipei, 13 December 2018

The Taiwan Transportation Safety Board (TTSB) has found that the captain of a China Airlines Boeing 747-400F (B-18717) that undershot a runway at Taipei Taoyuan International airport had inadequate rest because of a crying baby at home. His diminished alertness meant that he was slow to notice that the co-pilot, who was flying the aircraft, was not managing the final approach path well. The pilot flying had disengaged the autopilot after the aircraft descended through 1,800ft and as the freighter approached runway 05L it first tracked above the approach glidepath. When the co-pilot increased the rate of descent to correct this, on short final approach the aircraft sank through the glidepath and touched down hard about 27m short of the runway threshold, striking several approach lights. The hard landing also caused minor damage to the main landing gear tyres. The investigation found that two days before the incident, the 44-year-old captain had disturbed sleep after returning from a late night flight, because of a crying baby in his home. Then, the night before the incident, his sleep was interrupted for the same reason and the TTSB judged this to be the reason why he did not intervene effectively during the poorly flown approach.

China Air Lines 747-400F

Source: AirTeamImages

China Airlines 747F captain had interrupted sleep before hard landing at Taipei, TTSB found

Conquest Air Convair C-131B, Miami, Florida, 8 February 2019

A captain’s decision to continue a flight despite engine trouble caused a Conquest Air Convair C-131B (N145GT) to crash into the Atlantic Ocean off the Florida coast, according the US National Transportation Safety Board (NTSB). The accident occurred during a cargo flight from Nassau’s Lynden Pindling International airport in the Bahamas to Miami-Opa Locka Executive airport. The NTSB’s report says that during the outbound flight to Nassau that day “the power [on the left engine] was stuck at 2,400rpm”, and the first officer’s attempts to use the left engine propeller control to change its rotation rate had no effect. The aircraft is powered by two Pratt & Whitney R-2800CB3 radial piston engines. After landing at Nassau, the pilots tried unsuccessfully to notify the Miami maintenance department about the problem via text message, and then decided they would try to reset the engine control upon engine restart and call maintenance if unsuccessful. The pilots were indeed able to reset the control, and they took off normally on the return flight from Nassau to Miami. However, as the aircraft climbed through 4,000ft the left engine rpm increased to 2,700, says the report. The captain took control from the first officer, levelled the aircraft at 4,500ft and decided to continue the roughly 160nm flight, nearly all of it over open water. The report says the first officer suggested that they return to Nassau, but the captain elected to continue. When the aircraft started descending, the right engine “began to surge and lose power”, leading the captain to shut it down and feather the propeller. The left engine then also surged and lost power. The aircraft ditched in the sea about 32nm east of Opa-Locka. The NTSB reports: “The captain was unresponsive after the impact and the first officer was unable to lift the him from his seat.” Then, because the cockpit was filling rapidly with water, the first officer grabbed the life raft and exited via a breach in the hull. A US Coast Guard helicopter rescued the first officer. The first officer reported he did not know why the engines failed. The NTSB reports that the aircraft sank and was not recovered and attributes the accident to “the captain’s decision to continue with the flight with a malfunctioning left engine propeller control and the subsequent loss of engine power on both engines for undetermined reasons”. The captain had logged 23,000h of flight time, while the first officer had 650h of experience, says the investigatory board.

Conquest Air Convair

Source: AirTeamImages

Conquest Air Convair C-131B crashed after captain continued Nassau-Miami flight with malfunctioning propeller control

Aeroflot Sukhoi Superjet 100, Moscow, 5 May 2019

Russian investigators probing the SSJ100 crash at Moscow Sheremetyevo airport are still awaiting results of fire and structural analyses before releasing their final report. The aircraft had returned to Sheremetyevo after suffering electrical system failures believed to have been associated with lightning strikes. The inquiry has yet to complete research into the risk of fire after a crash-landing, which is being carried out by St Petersburg university for the state fire service, and it is also awaiting the results of undercarriage load modelling being performed by French aerospace manufacturer Safran. While returning to Sheremetyevo after a lightning strike, the aircraft bounced high on landing. Its landing-gear failed during the impact and the subsequent damage to the engines and fuel tanks led to a severe fire as the jet came to a halt, resulting in 41 fatalities. Structural lightning-strike analysis has been carried out in co-operation with Aeroflot, federal air transport regulator Rosaviatsia and Sukhoi and research has also been undertaken into the avionics, electronic engine management system, flight controls, fuel controls, power supplies, radio equipment, shut-off valves and weather radar.

Biman Bangladesh Bombardier Q400, Yangon, 8 May 2019

Myanmar investigators have determined that a Biman Bangladesh Bombardier Q400 crew engaged reverse thrust before final touchdown following an unstable approach to runway 21 at Yangon. The Q400 (S2-AGQ) struck the runway hard and broke up. The aircraft had been inbound from Dhaka’s Shahjalal airport, with 28 passengers and six crew, and they had already abandoned the first attempt at an approach because airport operations were suspended for 30min, owing to heavy rain and lightning. The glideslope was out of service and only the localiser was available. Once the airport reopened, the Q400 crew commenced a localiser-only approach to runway 21. Meteorological data shows variable winds at 10kt gusting to 20kt with 1.6nm visibility and broken cloud at 1,000ft. The captain reported that the aircraft encountered rain on the final approach at 1,500ft. The aircraft was on the centreline, reported the captain, but above the normal 3° descent path, as revealed by the precision approach path indicator. The first officer, who was flying, said the runway was visible, despite the rain. But the inquiry says the aircraft’s airspeed had dropped below the target 135kt at about 450ft before increasing again on short final approach. The flight-data recorder indicates both pilots, at this point, were making pitch inputs to their control columns, in opposite directions – the captain pushing nose-down and the first officer pulling nose-up. The main landing-gear touched down and bounced, providing “several” weight-on-wheels recordings, before the pitch increased and the aircraft became airborne again, rising to a height of 44ft. Power levers were retarded to the point where the propellers entered the fine-pitch beta range, essentially engaging reverse thrust while airborne. The report comments: “Activation of beta range would reduce the lift production of the wing significantly and cause a nose-down pitching moment.” The Q400’s airspeed dropped and, 13s after the initial touchdown, the aircraft struck the ground and exited the runway, suffering a landing-gear collapse and breaking into three sections. There were no fatalities but 12 of the 34 occupants were seriously injured.

S2-AGQ_Biman_Bangladesh Q400 c Wikimedia Commons_Shadman Samee

Source: Wikimedia Commons/Shadman Samee

Biman Bangladesh Q400 crew broke up on landing after crew used reverse thrust on approach

British Airways Boeing 747-400, London, 9 June 2019 

On reaching a cruising altitude of flight level 330 (33,000ft) having departed London Heathrow airport bound for Phoenix, Arizona, a British Airways Boeing 747-400 (G-BNLN) experienced unreliable airspeed indications resulting in overspeed warnings and activation of the stall warning system. In this incident, according to the UK Air Accident Investigation Branch (AAIB), the engine indication and crew alerting system showed a host of alerts: red overspeed warning, altitude disagree, indicated airspeed (IAS) disagree, rudder ratio single, airspeed low and altitude alert. The crew also remarked that a line appeared through the vertical navigation path on the flight mode annunciator. The auto-thrust reduced power and the autopilot was disconnected. The crew declared a pan emergency, the co-pilot (pilot flying) carried out a recall drill adopting a pitch attitude of 4° nose up and power at 80% N1, but later adjusted these to 3.5° and 87.5%, having run through the quick reference handbook (QRH) drill. While doing this the stickshaker activated, and the crew decided it must carry out the stall recovery drill. The co-pilot accordingly selected a nose-down attitude of 1°, and the stall warning stopped, which caused the crew to believe the stall had been real. Gradually the co-pilot tried transitioning back to the QRH datums, but the stall warning recurred and the pilot put the nose down again until the warning ceased. The crew went through this cycle several times until the QRH datums were reached, and the stall warnings ceased. This had caused a loss of height of about 2,800ft, for which ATC had cleared them. Investigators found that, after initially adopting the airspeed unreliable attitude and power, the aircraft’s engineering quick access recorder confirmed that the IAS was 266 and the Mach number 0.73. Completing the rest of the QRH airspeed unreliable drill involved changing from the right air data computer (ADC) to the centre one, and this allowed the autopilot and autothrust to be re-engaged. Radio communication with the engineering department allowed the fault to be confirmed as a failure of the right ADC. Having checked minimum equipment lists, the crew decided to continue to their destination. The AAIB concurred that the probable cause was a fault with the right ADC, although this could not be replicated in tests. As a result of this incident, the aircraft manufacturer is providing additional information as part of its published unreliable airspeed procedure.

Delta Air Lines Boeing 757-200, Azores, 18 August 2019

Portuguese investigators believe a failure to control the derotation of a Delta Air Lines Boeing 757-200 resulted in a heavy nose-gear impact that was severe enough to buckle the fuselage. The aircraft (N543US), arriving in the Azores from New York JFK airport, had touched down normally with its main landing-gear on Ponta Delgada’s runway 12. Portuguese accident investigation authority GPIAAF says the first officer’s piloting technique – which demonstrated “excessive corrections” of attitude and thrust, possibly in response to a variable crosswind – resulted in a heavy nose-down elevator input after the main gear contact. Flight-data recordings indicate a 1.53g main-gear contact followed by a nose-gear impact of 1.88g, says GPIAAF. The aircraft had been operating at just 1% below its maximum landing weight of 89.8t and the inquiry believes this contributed to the extent of structural damage. Several fuselage areas suffered deformation from compression stresses, with stringers cracking and skin wrinkling evident on the upper central and lower forward fuselage consistent with nose-gear overload. The flight data reveals several control column pitch movements of “increasing amplitude” in the moments before landing, says the inquiry, followed by a sharp nose-down input after main-gear touchdown and then a sudden nose-up correction after the nose-gear impact. Boeing had previously detailed the risk of damage from hard nose-gear contacts on the 757 and 767 resulting from full or nearly-full forward control-column input after main-gear touchdown. “Enough nose-down elevator authority exists to damage the airframe structure if the [aircraft] is rapidly de-rotated following main-gear touchdown,” it stated in an April 2002 analysis. Boeing adds that aircraft damage from such accidents is typically “significant” and results in “lengthy and expensive repairs”.

EasyJet Airbus A319, Nice, 29 August 2019

During their initial pre-flight preparation, the crew of an EasyJet Airbus A319 (G-EZBI) chose to calculate take-off performance based on the most limiting intersection available, Bravo 3, on runway 04R at Nice Cote d’Azur airport. The aircraft actually departed from intersection Alpha 3 where the runway length available was 316m greater than from Bravo 3. But at lift-off, the commander noted that the departure end of the runway was closer than he would have expected, but he did not perceive any other performance issues. Subsequent analysis indicated that both pilots had inadvertently used performance figures for a departure from intersection Quebec 3, from which the available runway is 701m greater than from Bravo 3. Since both pilots made the same mis-selection, the take-off performance cross-check was invalid, and the error went undetected. In fact, the cross-check of their independent performance calculations revealed a 1kt discrepancy between take-off speeds, which the pilots considered acceptable. As they approached the runway, the flightcrew were offered a departure from Alpha 3, and believing that they had the more-limiting Bravo 3 performance figures entered into the flight management computer, the crew accepted this clearance and did not change any settings. On reaching V1, the aircraft commander considered that the runway remaining was less than he would have expected, but not alarmingly so. The procedure of choosing to calculate take-off performance according to the most limiting likely clearance is adopted because revising take-off calculations after engine start typically requires aircraft data entry modifications and possible changes to aircraft configuration during the taxi phase. This presents an additional opportunity for error at a critical stage of the flight.

Aeroflot Boeing 777-300ER, 18 December 2019

Russian investigators have reported on a serious incident involving an Aeroflot Boeing 777-300ER that captured a false glideslope below the correct one on approach to the new runway 24R at Moscow Sheremetyevo airport, descending to low altitude before executing a go-around. The crew initiated a go-around after the ground-proximity warning system sounded, according to a communication from Rosaviatsia. In December, a local campaign group publicly highlighted an incident in which an aircraft had been observed below the sixth floor of a high-rise accommodation block, descending through fog while still 2.7nm from the airport. Rosaviatsia has confirmed that an Aeroflot 777 was involved. It says the descent below the correct approach path to 24R occurred as a result of aircraft systems capturing a false glideslope – but has not elaborated on this claim. Rosaviatsia adds that the Russian state air traffic management corporation carried out further analysis of the 777 flight – the SU209 service from Shanghai – with the aim of providing crews with effective information about deviations from approach paths.


Airline safety review January-June 2020