How fatal lapses impacted airline safety in 2021

In 2021 the airline world saw only one fatal passenger jet crash, but many accidents involving small and medium-sized turboprops. This demonstrates yet again how close the global airline industry is to achieving a zero fatal accident rate for mainline jet operations, stymied usually by a mishap in one of a few nations whose safety performance stubbornly remains below the world average.

Altogether last year there were 15 fatal airline accidents, which caused a total of 134 crew and passenger deaths. Comparing these numbers to those in 2019 – the last year of pre-pandemic normal operations – the figures then were respectively 22 and 297.

In the first full year of operations affected by the Covid-19 crisis – 2020 – there were 12 fatal accidents and 332 fatalities, but flight numbers were down by more than 70% compared with pre-pandemic years. In 2021 commercial air transport had begun to recover, but traffic was still well short of normal levels.

Approach and landing accidents caused the largest proportion of fatal crashes in 2021, specifically nine out of the total 15 fatal mishaps. All of these involved turboprop aircraft, most of them on non-precision approaches.

The only fatal accident involving a passenger jet last year – on 9 January – involved Indonesia’s Sriwijaya Air. The Boeing 737-500 crew, during the climb-out from Jakarta International airport, somehow managed to ignore a slowly developing power asymmetry, according to Indonesian investigator KNKT’s preliminary report. The left engine was throttling back, the right remaining as set for the climb. The situation should have been manageable had it been monitored, but the power disparity continued to increase until the asymmetric thrust affected control of the aircraft.

At that point, the autopilot and auto-thrust tripped out, and the left wing dropped. The crew then seemed unable to regain control in the instrument meteorological conditions that prevailed. All 62 people on board lost their lives.

There was a similarly badly handled jet crash reported in FlightGlobal’s airline accident review of the previous year, involving a Pakistan International Airlines Airbus A320 approaching Karachi airport in March 2020.

CREW BEHAVIOUR

Having consulted the Pakistan investigator’s preliminary report on the accident, the FlightGlobal analysis for that year commented: “The Pakistan International Airlines fatal accident at Karachi seems to be a case of a crew breaking every rule that applies to the safe conduct of a final approach to land, leaving the reader of the initial report wide-eyed with disbelief at the crew’s behaviour. The inquiry needs to establish not only what happened, but what state of mind the crew was in, and why.”

The same challenge exists for the investigators of the Sriwijaya accident, and for the aviation authorities in the two nations in which these aircraft were registered and the crews selected and trained.

The year’s second-deadliest accident happened on 6 July, when an Antonov An-26 operated by Kamchatka Aviation Enterprise crashed into a cliff while on approach to Palana, Russia. All six crew members and 22 passengers were killed.

Among the non-fatal incidents listed in 2021 there were two serious uncontained engine failures: on 20 February, a United Airlines 777 suffered an uncontained failure and fire of its right Pratt & Whitney PW4000 engine as it climbed out of Denver airport, so the crew returned there to land. And on 11 March, a Transcarga International Airways A300F suffered a turbine disc failure of its left GE Aviation CF6 during the take-off run at Maiquetia, Venezuela, so the crew aborted the departure.

The forced ditching of a 46-year-old Transair 737-200F shortly after take-off from Honolulu, Hawaii on 2 July was an example of how much damage even a controlled touchdown on water causes. The crew reported trouble with the left engine and said that they could not maintain height on power from the other.

A return to the airport was not possible, so the crew ditched the 737 a few miles off the coast of Oahu Island. The airframe broke up, but the two pilots, wounded and clinging to wreckage, were rescued.

Russian carrier S7 Airlines provided another variation on what can happen if de-icing is not carried out completely over the whole airframe. Early studies by Russian accident investigator Rosaviatsia indicate that the problems the crew faced when climbing away from Magadan in freezing conditions on 2 December were the result of unreliable static and dynamic pressure feed to its air data computers, caused by ice ridges ahead of the pitot/static sensors at the nose that disturbed the airflow. These ridges were generated, believes Rosaviatsia, when the crew of an A321neo had turned on the windscreen heaters, melted the snow and ice on the screens, and water flowed down the sides of the nose and froze in the -9°C (16°F) temperature.

Director of Safety at Ascend by Cirium, Paul Hayes, sums up 2021: “As in many of the previous years, all the accidents were suffered by small domestic or regional carriers which are probably little known – or totally unknown – outside the markets they serve, many of them happening in remote areas with limited support structures, few navigation aids, and limited weather reporting.

“That said, I think the level of safety improvement globally, if measured by the fatal accident rate, may have slowed in the last few years. However, using global figures is probably misleading, as the large airlines that carry most of the passengers and freight hardly ever suffer fatal accidents. It is the small local carriers, mainly in the developing world, that do – although, even here, things have improved considerably from 10 or 20 years ago.”

The lack of recent flying experience for pilots is a problem worrying the entire industry at present, after many flights were cancelled and aircraft and crews grounded as a result of the pandemic. Embry-Riddle Aeronautical University has published the results of a study on the subject. The study’s principal investigator, adjunct professor Dr Rajee Olaganathan, reports finding a 50% increase in pilot errors following the pandemic-related shutdown in the summer of 2020.

“What surprised me was the level of skills deterioration over such a short duration. Skill knowledge is acquired slowly through related experience and practice. When flying hours are reduced, it will have an effect on the pilots’ skills,” Olaganathan says.

She adds that the biggest reduction in global airline flight operations during the pandemic occurred in May 2020, when services reduced by 70.6% compared to the level of service one year prior. In the USA alone, that translated to a total of 532,834 fewer flights than in May 2019.

“The current Covid-19 scenario made it difficult for pilots to achieve federal requirements. It also placed a burden on pilots to maintain their currency and proficiency, due to lack of access to aircraft following industry-wide furloughs and layoffs,” Olaganathan says. “Because of that, the number of safety incidents related to pilot proficiency increased tremendously during this pandemic period.”

REDUCED FLYING

In order to maintain safety certifications, pilots are required to perform at least three take-offs and landings per 90-day period – but due to shutdowns, that was impossible for many. This has led to some airlines practicing work-sharing: a schedule in which flights are assigned evenly among all on-staff pilots to ensure equal practice opportunities.

Meanwhile, Olaganathan recommends flexible training programmes and webinars for pilots re-entering work, ranging from theory refreshers to multiple simulator sessions, as well as supervised in-flight checks, depending on the length of absence. She says: “Pilots also need to make an honest assessment of their skills and confidence upon returning to work. They may need to turn down offers like shorter landing approaches from air traffic control, if they do not feel ready.”

An example on 13 September of an incident suspected to be related to flying recency for the crew is under investigation by the UK Air Accidents Investigation Branch (AAIB), although no crew or passengers were injured and the aircraft – a TUI Airways 737-800 – was undamaged.

The incident occurred on approach to Aberdeen airport, Scotland. A late demand by air traffic control for the aircraft to abandon its approach because a search and rescue helicopter had been scrambled from the airport presented the crew with a high-workload situation that they would probably have managed well in a year of normal operations.

Following the order to go around, the crew selected take-off/go-around power on the throttles and initially had problems with height management as the power surged and they aimed for their allocated height, but quickly got the aircraft back on its cleared trajectory and landed safely.

The AAIB notes that both the crew, but particularly the co-pilot, had flown little in the past year, although they had been provided with simulator practice. The investigation continues and will report further.

Meanwhile, during 2021, an extraordinary anomaly in the history of commercial aviation safety – the grounding of the 737 Max series – was slowly being consigned to history. The Max has been cleared to operate again in almost all the world’s countries. Its original grounding in March 2019 was reversed in November 2020 by the US Federal Aviation Administration (FAA), then by the European Union Aviation Safety Agency early in 2021, and since then gradually by almost all the rest of the world.

Indonesia’s approval came in late December, and China has issued an airworthiness directive that paves the way for its own approval.

The two fatal Max crashes in 2018 and 2019 had a distorting effect on the world’s civil aviation safety figures in those years. It was these disasters, involving Indonesia’s Lion Air and Ethiopian Airlines, that precipitated the grounding, because they revealed a systems design failure in the aircraft’s manoeuvring characteristics augmentation system (MCAS); a function unique to the Max variant in the 737 series.

Now, however, following extensive systems redesign involving both the hardware and software of the notorious MCAS and its sensor inputs, the Max’s technical problems – and the calamitous failures of oversight at Boeing and the FAA that allowed the faults to enter airline operations – should finally now be history.

RESUMING OPERATIONS

Ethiopian Airlines says it anticipates starting Max operations again in February 2022. The carrier has four examples in storage currently.

World airline safety performance in the year just ended was not exceptional in any way, but because of the effects of the Covid-19 pandemic on operations, neither can it be considered normal.

Safety forums around the world continue to call for vigilance in the face of uncertainty, particularly regarding the wellbeing of safety-critical employees like engineers and pilots who may have been furloughed, but also because of the care needed to bring long-parked aircraft back into service.

So far it seems largely to be working, but as the interruptions to normal service continue, the continuing stresses imposed on the industry may cause unnoticed fatigue cracks in the human infrastructure.