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Boeing: crashed and grounded

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Two crashes of Boeing’s popular 737 MAX aircraft minutes within take-off raise questions about safety and control systems.

The story so far

The crash of an Ethiopian Airlines plane, five months after the Lion Air crash in Indonesia, has forced Boeing to ground all its 737 MAX aircraft.

What is 737 MAX?

The Boeing 737 MAX series is a single aisle aircraft fitted with high-bypass twin-turbofan engines. It is the fourth generation variant of the Boeing 737 aircraft, a base model which has been in production since the 1960s. In the commercial aviation business, it is locked in competition with the Airbus A320, another single aisle and newer aircraft family, manufactured by Boeing’s European rival, Airbus SE, in the high stakes and crucial short-haul aircraft market.

For Boeing, this model is the fastest-selling aircraft in its history — it cites about 5,000 orders from over 100 customers. Currently, there are four commercial variants (MAX 7, 8, 9, 10), with a seating capacity that varies between 172 and 230. With its CFM-manufactured LEAP engines, the 737 MAX family has, depending on the variant, a flying range of up to 7,130 km. The suffix MAX is a coinage meant to highlight the potential of the aircraft in offering the “maximum competitive advantage” to customers.

The flight deck and cabin have had several enhancements, which include more flight control software, some automated controls and touches such as better lighting and overhead storage. The engines, which have composite components in some stages, offer significantly better fuel efficiency — a key draw for customers — compared to earlier engines on the third generation 737 variants.

What led to the global grounding?

On October 29 last year, a two-month-old Boeing 737 MAX 8, operated by low-cost airline Lion Air of Indonesia, crashed approximately 12 minutes after being airborne, killing its 189 passengers and crew. The pilot, with more than 6,000 flight hours and the co-pilot, with more than 5,000 hours, formed an experienced team. Last Sunday, on March 10, another flight by a four-month-old 737 MAX 8, operated by Ethiopian Airlines, crashed approximately six minutes after takeoff. All 157 passengers and crew were killed.

The disparity in the flight hours of the crew, about 8,000 for the pilot, and just 200 hours for the co-pilot, has led to some scrutiny. Similarities between the two events, of the flight crew reporting certain technical difficulties, requesting a return to base, the scientific tracking of an unstable flight trajectory and airspeeds and also the ‘gathering of some technical evidence’ (in Ethiopia), have led analysts to conclude that there could be an issue with one of the aircraft’s key control systems. It may take time for data from the black boxes to be analysed and acted upon.

How did India react?

It was in two quick stages, which impacted the operations of the country’s two 737 MAX operators, private airlines Jet Airways and SpiceJet, with a fleet of 5 and 12 aircraft respectively (according to data from the Directorate-General of Civil Aviation, the country’s nodal aviation agency). Another aircraft data site puts the fleet composition at 9 and 14 respectively. The DGCA initially permitted operations to continue, with key directives that kicked in from March 12.

In a notice, dated March 11 (now withdrawn), taking into account “compliance of all manufacturer Standard Operating Procedures/operations circulars and Federal Aviation Administration [FAA] emergency Airworthiness Directives,” it advised additional actions for airline engineers and maintenance crew such as “no minimum equipment list (MEL) release” — a list which allows aircraft operation, under specified conditions — if there were control system red flags. It also mandated key checks during aircraft transit. Finally, flight operations departments were to ensure, among other things, that the minimum experience levels of the two pilots were “1,000 and 500 hours” respectively.

The DGCA said these were “interim safety measures” and there was communication with the manufacturer and the FAA. On March 13, it issued a follow-up notice, deciding that “the operation of B-737 MAX aircraft would not take place from/to Indian airports and transit or enter into Indian airspace effective from March 13 till further notice.” All operations ceased by 4 p.m. local time.

How was it overseas?

The ban was rolled out in phases. In the Asia-Pacific region, the grounding, on March 11, by the Civil Aviation Administration of China, which took the global lead, has hit the largest 737 MAX fleet in operation. Figures (compiled in early March 2018) from a leading fleet data site show that of the estimated 371 MAX aircraft in operation, a quarter, or close to 97 planes, are used by a raft of China-based airlines. With over 50 operators based in 34 countries, the Asia-Pacific region is the base for close to 37% of the worldwide fleet. The U.S. follows next with 30.2%. The situation was a bit different in the U.S., with the FAA playing outlier and then announcing a grounding.

Is the aircraft flawed?

We don’t now as yet. Some media reports cite the huge financial impact of the global grounding per day and potential damage to an order book estimated to be several billions — there is even a figure of “half-a-trillion dollars” floating around. Even worse are signs of a loss in airline confidence: some affected airlines are contemplating demanding compensation (low-cost carrier Norwegian Air has been quite vocal about this, highlighting a “1% loss of its seat capacity”), while other carriers, such as Lion Air, are trying to up the ante by making veiled threats of order cancellations and buying Airbus aircraft. Kenya Airways, though not a 737 MAX operator, says it could re-consider a potential order. Some others still are considering scouting around for third generation and “safer” 737 variants.

But the main attention is now on a control system in the plane. Preliminary analysis of both crashes has focussed on the “anti-stalling system” called the Manoeuvering Characteristics Augmentation System (MCAS). It was introduced after the newer and more fuel efficient engines for this aircraft type, which have a much larger diameter and heavier weight than earlier ones, have had to be fixed higher and more forward on the wings than done previously for the earlier 737 models, consequently making changes to the aircraft’s flight profile. As a result, there has been a possibility of the aircraft, while in flight, pitching a bit more higher than intended. In certain stages of flight, this could lead to what is called a stall which can have dangerous consequences.

The automated MCAS comes in here. With the Angle of Attack (AoA) sensors, it detects when the aircraft is at risk and initiates corrective manoeuvres using the stabilisers. A senior Boeing 737 pilot told The Hindu that the MCAS is supposed “to work quietly in the background.” The MCAS could force the aircraft into a dive if there are erroneous inputs from the AoA sensors (An FAA emergency airworthiness directive highlighted this). After the Indonesia crash, some pilot unions, especially in the U.S., flagged it as being a nasty surprise and there having been inadequate exposure to, information about and training for this feature. There is some commentary on this putting it down to the manufacturer not thinking of creating awareness of this feature to be a necessity.

Are safety issues new to aviation?

No. Aviation incidents have led to a review of every aspect of the aviation ecosystem. For example, Airbus SE faced a crisis when its Airbus A320 aircraft suffered accidents just after its introduction (1988 onwards); there was one incident in India (1990). Its “fly-by wire” controls were deemed too advanced and complex but the aircraft flies on, ticking many boxes for several airlines. More recently, Airbus had a significant technical issue with an engine type (the manufacturer is sorting it out) on its Airbus A320 Neo aircraft. In 2013, Boeing rode out a crisis, but with the cost of compensation, affecting its composite-built aircraft, the Boeing 787 ‘Dreamliner’, and involving its lithium-ion batteries.

Where does this leave Boeing?

An extended grounding — which some experts estimate could be till May or beyond — could hit its bottom line. The Ethiopian crash even caused it to drastically tone down the unveiling of a newer model of its flagship Boeing 777 family, with its unique feature of partially folding wings. Given the reported conflict of interest in certification of aircraft, Boeing will have to work fast and transparently.

It will have to look at tackling the issue from three angles, as aviation experts like Diogenis Papiomytis of consulting firm Frost and Sullivan have suggested: if it is a software issue, it could be sorted out in the planned battery of software upgrades — this could be soon. If it is about better pilot training, it will have to work out revamped and comprehensive training modules across the world and additional type certification. Aviation authorities will also have to maintain vigil as passenger safety is paramount.

This could affect some airlines in terms of costs. Finally, if it is traced to a structural issue, the American aerospace giant could be hitting an air pocket, with ripple effects down the aviation global supply chain. The 737 is a cash cow, but there are already those who accuse Boeing of pushing its 52-year-old plane model too far. It’s over to Renton now.

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Printable version | Jan 24, 2020 10:25:01 AM | https://www.thehindu.com/business/boeing-crashed-and-grounded/article26555309.ece

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