The world’s airline safety performance figures for 2018 may compare unfavourably with those for the previous three years. But a glance at the fatal accident totals for the years before 2015 shows that aviation safety trends over the longer term still appear to be heading in the right direction (see graph).

There were 14 fatal airline accidents in the year just ended, and 543 people died in them. That looks terrible, compared with the 2017 figures of 12 and 56 respectively, and compared with the best-ever year – 2015 – in which there were only nine fatal accidents, even if they resulted in 176 casualties.

In an era when the number of serious accidents is small compared with the numbers in earlier decades, a single year can produce a statistical “spike” in either direction just by having one more – or one fewer – crash involving a large aircraft with a high passenger load.

The bad news in 2018 was that six of the fatal accidents involved large passenger jets, which marked a dramatic contrast with 2017 in which all the fatal crashes that occurred involved relatively small turboprop-powered aircraft, or pure freighters, and no passenger jets at all.

But to put these six big-jet fatal accidents into perspective, it is important to point out that in three of them only one passenger was lost in each event. Unfortunately, in the other three, very nearly all on board were killed. To make the 2018 numbers worse, two of the turboprops that crashed catastrophically were also high-capacity aircraft carrying full passenger loads.

The first of the jet disasters was a sad but simple tale, according to the Russian investigators, in which the Saratov Airlines Antonov An-148 crew failed to turn any of the pitot heaters on for a take-off from Moscow in February, leading to loss of airspeed and altitude readings soon after getting airborne, then loss of control.

The Cuban authorities have provided no preliminary information yet about the 18 May Cubana Boeing 737-200 accident near Havana, but video footage shows the aircraft falling out of a high nose-up climb just after take-off. Speculation about an engine failure and stall have not been confirmed.

The third jet disaster involving the Lion Air Boeing 737 Max 8 in late October is complicated, and its implications are examined later in this article. In terms of fatalities, it was by far the worst accident of the year. Lion Air also had a non-fatal but serious accident on 29 April, where a Boeing 737-800 landed at Gorontalo in the rain, ran off the runway into mud, and all the crew’s communications with air traffic control (ATC) and the cabin failed.

The first of the two big turboprop crashes involved an Iran Aseman Airlines ATR72 hitting high ground in snow during an old-fashioned non-directional beacon (NDB) approach to a town in a deep valley surrounded by high mountains.

The unanswered question is why the aircraft’s terrain awareness and warning system (TAWS) did not save the aircraft from an accident that looks like controlled flight into terrain, an accident category that TAWS was supposed to eliminate.

In the second serious turboprop crash, involving a US-Bangla Airlines Bombardier Q400 attempting a landing at Kathmandu, there appears to have been a major misunderstanding between the crew and ATC, followed by loss of control at low level, possibly caused by distraction.

US-Bangla Kathmandu 640 c Narendra Shrestha EPA-EF

US-Bangla Bombardier Q400 crash, Kathmandu

Narendra Shrestha/EPA-EFE/REX/Shutterstock

In the non-fatal accident listings there are as many damaging runway excursions as there seem to be every year, despite industry attempts to persuade pilots to concentrate on stabilising approaches in good time to ensure a stable landing. Meanwhile there have been so many ground collisions during taxiing that they are not listed here, usually very expensive impacts involving wingtips striking the tails or wingtips of other aircraft. Insurers are increasingly refusing to cover these.

Runway incursions and airport navigation errors, too, are back. In August a Jet Airways 737 attempted a take-off at Riyadh from a parallel taxiway instead of the runway, and in September an Air Arabia Airbus A320 was cleared to take off from an intersection on Sharjah’s very long runway 30, but turned the wrong way at line-up and began take-off in the reciprocal direction (12) to that for which the flight was cleared. The captain realised distance was running out and selected full power just in time to clear the approach lights.

By and large this year has been unexceptional, with lots of accidents and incidents caused by the traditional hazards that have always lain in wait for aviators, with no clear theme and virtually no “black swan” total surprises.

The exception to that was the Lion Air accident that happened a little more than 10min after departure from Jakarta on a short domestic flight.

STUNNING EVENT

The greatest shock of 2018 was the total loss, on 29 October, of an almost brand-new Boeing 737 Max 8, operated by Indonesian carrier Lion Air, in which all 189 people on board died when it dived into the sea near Java.

It was a shock because – for many years – there has been complete aviation industry unanimity behind the contention that the dominant factor driving world airline safety performance improvement over the past four decades has been advancing cockpit technology and systems reliability, so when the crew of one of Boeing’s latest-generation narrowbodies appeared to lose control of their aircraft, there was a significantly heightened surprise factor.

The preliminary report from Indonesia’s National Transportation Safety Committee (NTSC) suggests that a factor in the sequence of events leading to the Lion Air crash was a faulty angle-of-attack (AoA) sensor. This device, says the report, sent false signals to a new stall protection system unique to the Max series of 737s, known as the manoeuvring control augmentation system (MCAS).

According to the report, these signals wrongly indicated a very high AoA, and the MCAS triggered the horizontal stabiliser to trim the aircraft nose-down. Boeing points out that the flightcrew operating manual contains a drill to deal with a runaway stabiliser trim, but the crew did not appear to recognise this event as a trim runaway, so did not apply the drill and the nose-down control force generated by the stabiliser seems to have resulted in a dive into the sea.

The NTSC’s preliminary report provides considerable detail about a flight from Denpasar to Jakarta in the same airframe on the previous day (28 October), when almost exactly the same sequence of events occurred, including the signal from the faulty AoA sensor.

But on that occasion the captain selected the STAB TRIM switches to CUT OUT and proceeded successfully to the scheduled destination, despite the checklist advice to divert to the nearest aerodrome. Indeed, the NTSC’s report provides more detail about that flight than the accident flight itself, prompting Boeing to observe: “Unlike as is stated with respect to the prior flight, the report does not state whether the pilots performed the runaway stabiliser procedure or cut out the stabiliser trim switches.”

Indonesia and Lion Air have a poor safety record compared with global averages, and the NTSC’s preliminary report contains a long list of safety actions to be carried out by Lion Air and its aircraft maintenance providers.

The report criticises the crew that survived the 28 October flight from Denpasar to Jakarta for deciding to continue to its destination, despite the fact that the captain’s stick shaker was operating continuously from just after take-off, rendering the aircraft unairworthy. It says Lion Air needs to “improve the safety culture”, the implication presumably being that a crew that can make a decision to continue a flight with an unairworthy aircraft demonstrates the absence of such a culture.

It also remarks that the weight and balance sheets showed five cabin crew on board, whereas there were in fact six of them. The sheer number of repeating faults, flight after flight, in the accident aircraft over the last few days before the crash has driven the investigators to call for more accurate technical reporting by Lion Air crews and better maintenance fault troubleshooting. And there is much more, despite the fact that this report is only the preliminary one.

Lion Air debris 640 c Xinhua News Agency REX Shutt

Lion Air 737 Max 8 crash debris

Xinhua News Agency/REX/Shutterstock

 

COMMUNICATION GAP

An unsettling fact that has emerged since the NTSC published its report is that some pilot associations in the USA whose members operate the Max have professed publicly that there was a widespread ignorance among Max-qualified pilots of the very existence of the MCAS, and also an assumption that a runaway trim would be dealt with in exactly the same way as it was for all the earlier 737 marques – which is not true. Meanwhile, the biggest pilot union, ALPA, has remained tight-lipped on the subject.

The reason for this professed pilot ignorance about the new MCAS system is unclear. Boeing explains the lack of fanfare about MCAS introduction in the Max by pointing out that it is a “variant” of the speed-related automatic stabiliser trim system on the 737NG series, but adds: “MCAS does not control the airplane in normal flight. It augments the stall recovery characteristics of the airplane in a non-normal part of the operating envelope.” The manufacturer also insists it has “discussed MCAS flight control functionality with more than 60 airline operators at several Service Ready Regional Conferences globally since 2016.”

An experienced Southwest Airlines 737 Max captain with whom FlightGlobal has discussed the MCAS issues since publication of the NTSC preliminary report has commented that, in practice, the 737NG and Max feel the same to fly. He did remark, however, that he was surprised that a single-point AoA sensor failure could be allowed to trigger what feels like a stabiliser trim runaway, venturing his individual opinion that this showed poor system redundancy design.

Also, a senior test pilot well known across the industry has spoken to FlightGlobal about issues surrounding the Lion Air loss, although at this stage of the investigation he is not prepared to venture technical opinions. His view – not directed specifically at any one aircraft manufacturer – is that the practice of extending common type ratings right across aircraft marques that have developed dramatically over several decades is due for a serious review. Certification standards relating to trimmable horizontal stabilisers need more scrutiny, he adds.

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It is easy to see why this test pilot raises the issue of thinly stretched common type ratings at this point. Pilots converting from earlier 737 marques to the Max are not required to undergo a new type rating course, because all 737s are deemed to have sufficient commonality to operate under the same type rating.

Pilots rated for the 737 being prepared for the Max are thus required only to undergo a brief “differences course”. Southwest Airlines pilots, for example, do their differences course entirely online, and American Airlines the same, so there is no practice in a flight simulation training device. Southwest expects to receive its first Max full flight simulator (FFS) in March next year.

The type conversion situation appears similar in Europe. Ryanair, which is to take delivery of its first Maxes at its London Stansted base in April 2019, says its differences course will be delivered via computer-based training. The course has been designed using input from Boeing and Ryanair and the airline says it will begin installing its first Max FFS simulator at its London Stansted training base in January.

Whatever additional light the NTSC final report is able to shed once it is published in a year or two from now, there appear to be some generic factors about the Lion Air accident that the industry cannot ignore. In the end, it was yet another loss of control in flight accident, and yet another tale of a mismatch between pilots and highly automated systems.

Work is already under way to make pilots more resistant to the “startle effect”, through selection and training, as well as the inculcation of better technical knowledge and understanding.

But information, and the way it is presented, is key. Crews on modern flightdecks are constantly bombarded with information to the point where quantity can become the problem, rather than the solution, and finding more intuitive ways of presenting the essential information is vital if crews and their aircraft are to operate better together when things go wrong.

World Airline fatal accidents and fatalities 2009-

 

Source: Flight International