737MAX: Ground or not to ground?

March 12, 2019

The fallout from the tragic crash of an Ethiopian Airlines three months old Boeing 737-8MAX continues to divide opinion over whether the type is safe or not.   The loss of flight ET302 on March 10 resulted in the death of all 157 passengers and crew on board.  It followed the crash of Lion Air flight 610 four and a half months earlier, in which 189 passengers lost their lives.  Observers noted some similarities between the two flights, with both accidents taking place shortly after departure and both trajectories appearing to be erratic based on un-verified data recordings from FlightRadar24.com.  With the new MCAS - Maneuvering Characteristics Augmentation System - Boeing installed on the 737MAX to counter aerodynamic deficiencies being implicated as a factor in the loss of Lion Air 610 (see KJM Today November 19, 2018 - Flying Blind), there is no shortage of 'experts' calling for the type to be grounded.

 

Indeed, a significant number of aviation authorities and airlines have grounded the 737MAX, possibly until such a time as the details of what happened to ET302 start to emerge.

 

Countries / operators that have grounded Boeing 737MAX aircraft include:

  • Argentina (5)

  • Australia (0)

  • Brazil (7)

  • Cayman Islands (2)

  • China (96)

  • Ethiopia (4)

  • Fiji (2)

  • Indonesia (13)

  • Korea (2)

  • Malaysia (0)

  • Mexico (6)

  • Mongolia (1)

  • Morocco (2)

  • Norway (18)

  • Oman (5)

  • Singapore (5)

  • South Africa (1)

  • United Kingdom (5)

Meanwhile, other authorities including the US Federal Aviation Authority (FAA) and the European Aviation Safety Agency (EASA), as well as the agencies responsible for certification and airworthiness in Canada, Iceland, India, Panama and Turkey have not intervened.  However, getting on for half of the in-service fleet is now grounded.

The list of countries in which the 737MAX is grounded is growing (Aka The Beav)

 

Southwest Airlines (31 aircraft) and flyDubai (14) say they remain "confident" in the Boeing planes after Ethiopia crash.  American Airlines (22) and United Airlines (12) in the US have adopted a similar stance.

 

A spokesman for TUI Airways in Europe (11 aircraft) has said "TUI Airways remain in close contact with the manufacturer and regulatory authorities and we have no indication that we cannot safely operate our 737 MAX aircraft. The safety and well being of our customers and staff remains our primary concern."

 

However, events subsequently overtook TUI's position when the UK Civil Aviation Authority (CAA) banned 737MAX aircraft from UK airspace.  A spokesperson said: "Our thoughts go out to everyone affected by the tragic incident in Ethiopia on Sunday.  The UK Civil Aviation Authority has been closely monitoring the situation, however, as we do not currently have sufficient information from the flight data recorder we have, as a precautionary measure, issued instructions to stop any commercial passenger flights from any operator arriving, departing or overflying UK airspace."

 

Norwegian has also followed and has grounded its MAX8s.  Many passengers have already shared that view, and have vowed not to travel on Boeing 737MAXs until the authorities investigating both accidents have provided further clarity over whether the aircraft is safe.

 

Ground or not to ground?

So which side is right: to ground or not to ground?  Firstly its important to point out that there is yet no direct evidence that the 737MAX is an unsafe design - would that be the case, there is no doubt that authorities such as the FAA and EASA would have issued unequivocal guidance on the matter.  The FAA has, however, already issued clarification of 737MAX operators, detailing how a malfunction of the aircraft's MCAS or the associated air data probes can be dealt with.  Questions are also being asked about whether the design of the link between the air data probes and the MCAS, which uses a 'single source of truth' is appropriate for air transport.

 

We do not ground aircraft types following a single accident - or even two involving the same type over a relatively short period of time.  Only when a trend is established that points to ongoing airworthiness questions will action be taken.   

 

US and European operators are continuing to fly the MAX.  (Anna Zvereva)

 

Grounding the 737MAX without quantifiable evidence that there is an intrinsic deficiency in the design would cause economic chaos for some of the type's operators.  However, human lives are worth more than the losses airlines would incur during a grounding.  

 

Its important to go back though to the impression provided by unofficial data sources that both 737MAX losses occurred under fairly similar circumstances.  The industry certifies on the basis that an aircraft must be 'proven' safe before it is allowed to carry passengers - it depends on demonstration that - as far as is reasonably possible - a type is safe.  Would the 737MAX be carrying passengers today had accidents similar to JT610 and ET302 occurred during test flying?  It would seem extremely unlikely, at least until the crash investigations were completed.  On that basis, why is the type carrying commercial passengers now?

 

The 737MAX has known and inherent stability issues which Boeing addressed using MCAS software.  It acts to ensure excessive high angles of attack (nose up attitudes) do not cause the aircraft to stall.  Such aerodynamics are normally reserved for fighter jets, where agility is paramount but the 737MAX's larger engines resulted in a reduction in the stability normally associated with airliners.  Software can never be proven to be 100% fault free - like aeroplanes it is exhaustively tested to expose any bugs and reduce the risk of failures / errors as much as possible.  But if a software error does arise, it has to be shut down / stopped until a fix is applied.  Similar action should be taken when problems arise with aircraft.  And even if other deficiencies are identified - such as pilot training or actions - accident investigation involves addressing ALL of the causes, not just the first or most obvious ones.

 

It is still entirely possible that JT610 and ET302 crashed for unrelated reasons, or that the aircraft design is not implicated or only played a subsidiary role in the tragedies.  Human lives are always worth more than the financial challengers operators and the manufacturer would face as a result of a grounding.  Until we know fore sure what caused these two aircraft to be lost, should the 737MAX not be grounded?

 

PS: Despite suggesting the 737MAX should be grounded pending the ongoing investigations, The Aviation Oracle would have no qualms about travelling on one as the chances of being involved in another incident are very remote.

Text © The Aviation Oracle

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