A US government report has found that Boeing purposefully held back information about the automated flight-control system on its re-engineered 737 Max during the aircraft’s certification process, that led to two fatal aircraft crashes that killed 346 people.

In a scathing 52-page report published on 1 July, the Department of Transportation’s (DOT) Inspector General writes that the Chicago-based manufacturer did not share vital information about the new aircraft’s Maneuvering Characteristics Augmentation System (MCAS) during the lengthy process, thus significantly downplaying the risk that it posed. 

The MCAS system as designed on the 737 Max relies on inputs from one angle of attack (AOA) sensor on the exterior of the aircraft. Should this sensor malfunction or deliver faulty information, the system could be triggered erroneously, and cause the aircraft to crash. 

The report says, in essence, that the Federal Aviation Administration (FAA) was kept in the dark about potential dangers of the flawed system, and therefore it was not able to adequately test or otherwise address it.

Boeing 737 Max 8

Source: Max Kingsley-Jones/FlightGlobal

IG report slams Boeing for holding back information on 737 Max

“Early in the process, Boeing included limited information in initial briefings to FAA on the MAX’s flight control software, MCAS, which subsequently has been cited as a contributing or potentially contributing factor in both accidents,” the watchdog report states. “Boeing presented the software as a modification to the existing speed trim system that would only activate under certain limited conditions. As such, MCAS was not an area of emphasis in FAA’s certification efforts and therefore did not receive a more detailed review or discussion between FAA engineers and Boeing.”

“As a result, FAA was not well positioned to mitigate any risks related to MCAS,” the report reads.

The report is rife with examples that show how Boeing downplayed the technical changes on the Max from previous generations of 737 aircraft. The manufacturer’s employees who were authorized by the FAA under the regulator’s “Organization Designation Authorization” (ODA) to act as its representatives during the process, portrayed MCAS “as a modification and not a new function”.

The FAA had created the ODA process in 2005, delegating some of the functions around certification to approved aerospace manufacturers, in order to standardise processes and potentially save time. Critics have described the ODA process as being ripe for abuse, saying that companies can place undue pressure on their employees assigned to ODA units.

During a technical familiarisation meeting in May 2012, for example, the MCAS was included as a “provisional modification to address the plane’s tendency to pitch upwards at high speeds”, but it was not emphasised as an area of focus. Just two lines of text in a set of 500 presentation slides referred to the system, the IG’s report says.

As a result, the FAA required no additional simulator training for pilots who were already qualified to fly previous generation 737NG aircraft even though the system was indeed a significant change from those aircraft. That aligned with Boeing’s and potential customers’ goals to keep training costs down as they integrated the new aircraft into their fleets.

Only after the first crash on 28 October 2018 did the FAA begin to take a closer look at the newly installed stabilisation system. During the short flight of Lion Air 610, MCAS was activated “based on faulty data from the aircraft’s external AOA sensor over 20 times, which led to loss of control of the aircraft.” The aircraft crashed into the Java Sea, killing all 189 aboard.

But even then, a Boeing-issued bulletin to operators - which prompted an FAA Emergency Airworthiness Directive, both in early November - did not specifically mention MCAS as a source of concern.

“This was the first time that FAA’s certification engineers had performed a detailed review of MCAS, and according to several FAA certification engineers, it was also the first time they were presented with a full picture of how MCAS worked,” the report says.

On 10 March 2019, Ethiopian Airlines flight 302 crashed just after take-off from Addis Ababa airport, killing 157, and once again MCAS was determined to be a decisive factor in the accident during which the pilots lost control of the aircraft. 

Two days later, on 12 March 2019, aviation authorities around the world began grounding the aircraft.

Over the past 16 months the grounding has led to a change in the leadership at the top of the world’s biggest aircraft manufacturer, and flushed out embarrassing lapses in judgement by Boeing employees working on the aircraft programme.

A trove of emails published in January contained foul language and disparaging remarks, painting a picture of company culture that was not aligned with its public commitment to safety. They show instances during which Boeing employees openly mocked company management, the US regulator and the ease of which certification was pushed through.

In one set of emails, a Boeing employee had said the aircraft “is designed by clowns who in turn are supervised by monkeys.” They called the design of the aircraft “piss poor”. Another complained about the FAA’s “whining”, as well as internal processes which slowed development of the aircraft.

For its part, Boeing says on 1 July that the company has made “substantial changes… to further enhance our commitment to safety [and] to improve our support to the regulatory process”.

“We have made robust improvements to the 737 Max flight control software, including ensuring MCAS cannot be activated based on signals from a single sensor and cannot be activated repeatedly,” Boeing says. “We have dedicated all resources necessary to ensure that the improvements to the 737 Max are comprehensive and thoroughly tested. We have also taken a number of actions to further improve the safety culture of our company.”

“When the Max returns to service, it will be one of the most thoroughly scrutinised aircraft in history, and we have full confidence in its safety,” Boeing adds.

The FAA has started recertification flights with the 737 Max earlier this week. These flights are among the final step prior to the FAA issuing an AD lifting the grounding. The AD will specify measures operators must take before returning the jets to revenue service.

Boeing has said it expects the AD will come in time to permit it to resume 737 Max deliveries in the third quarter of the year.

But the FAA warns that though this is an important step in the process, there are still numerous hurdles for the aircraft before it can return to transporting passengers.