Boeing made “extensive efforts to cut costs” in the 737 Max programme which “jeopardised the safety of the flying public” while under “tremendous financial pressure” to compete with the Airbus A320neo, an official report found.

The US aircraft manufacturing giant withheld crucial safety information from regulators and pilots, including details about a new flight control system that contributed to two 737 Max crashes which killed 346 people, according to the US congressional transportation committee investigation.

Both Boeing and the Federal Aviation Administration are both heavily criticised in the 238-page report which found a series of failures in the design of the Max.

The new generation aircraft, which has been ordered by European airlines such as British Airways, Ryanair and Tui, has been grounded since March 2019 after the crashes in Indonesia and Ethiopia.

The report, following an 18-month probe, said that both Boeing and the FAA share responsibility for the development and ultimate certification of an aircraft that was “unsafe”.

“Despite the promise of a technically improved, energy efficient, and financially competitive aircraft that could compete with the Airbus A320neo aircraft, there was trouble on the 737 Max from the very start. Boeing’s 737 Max aircraft had technical and operational issues that should have served as an early warning sign of bigger troubles yet to come.”

The investigation revealed “multiple missed opportunities” that could have turned the trajectory of the Max’s design and development toward a safer course “due to flawed technical design criteria, faulty assumptions about pilot response times, and production pressures”.

The FAA “also missed its own opportunities to change the direction of the 737 Max based on its aviation safety mission.

“Boeing failed in its design and development of the Max, and the FAA failed in its oversight of Boeing and its certification of the aircraft.

“The fact that a compliant airplane suffered from two deadly crashes in less than five months is clear evidence that the current regulatory system is fundamentally flawed and needs to be repaired.”

The two crashes “were the horrific culmination of a series of faulty technical assumptions by Boeing’s engineers, a lack of transparency on the part of Boeing’s management, and grossly insufficient oversight by the FAA – the pernicious result of regulatory capture on the part of the FAA with respect to its responsibilities to perform robust oversight of Boeing and to ensure the safety of the flying public.”

It added: “Both must learn critical lessons from these tragic accidents to improve the certification process, and the FAA must dramatically amplify and improve its oversight of Boeing.

“While the changes that the FAA and Boeing have proposed will be the start of a long process, changing the fundamental cultural issues that led to an environment that permitted Boeing to build, and FAA to certify, a technologically faulty aircraft will take much longer.

“This report’s main investigative findings point to a company culture that is in serious need of a safety reset. Boeing has gone from being a great engineering company to being a big business focused on financial success.

“Continuing on the same path it followed with the 737 Max, where safety was sacrificed to production pressures, exposes the company to potentially repeating those mistakes and to additional reputational damage and financial losses.

“One of the first steps on a new path is understanding and acknowledging the problems that did occur, the technical mistakes that were made, and the management missteps that led to the 737 Max tragedies and the preventable death of 346 people.

“However, the committee’s investigation leaves open the question of Boeing’s willingness to admit to and learn from the company’s mistakes.”

The committee was critical of news media suggestions that Boeing was trying to change the name of the aircraft from the 737 Max to the 737-8 “in an effort to combat the indelible image problems now surrounding the aircraft”.

It added: “If the committee’s investigation offers any lessons for Boeing, it is that a name change and a public relations effort will not address the cultural issues at Boeing that hampered the safety of the 737 Max in the first place and ultimately led to two fatal accidents and the death of 346 people.

“A name change may help confront a public relations problem, but only a genuine, holistic, and assertive commitment to changing the cultural issues unearthed in the committee’s investigation at both Boeing and the FAA can enhance aviation safety and truly help both Boeing and the FAA learn from the dire lessons of the 737 Max tragedies.”

Turning to the regulator, the report said: “The Max crashes show that the FAA must develop a more aggressive certification and oversight structure to ensure safe aircraft designs.

“Traditionally, the FAA has been the primary leader of the world’s civilian aviation authorities, but questions raised about the FAA’s role in the 737 Max crisis have punctured its reputation as the gold standard in aviation safety and international civil aviation authorities have clashed with the FAA over the 737 Max.

“As regulators have historically presented a united front in public, the reported disagreements between foreign authorities and the FAA provides insight into the reputational damage suffered by the agency in the wake of the 737 Max crashes.”

In response to the findings, Boeing said: “We have learned many hard lessons as a company from the accidents of Lion Air Flight 610 and Ethiopian Airlines Flight 302, and from the mistakes we have made.

“As this report recognises, we have made fundamental changes to our company as a result, and continue to look for ways to improve.

“Change is always hard and requires daily commitment, but we as a company are dedicated to doing the work.”

The FAA said it would work to “implement improvements identified in the report”.

The European Union Aviation Safety Agency (EASA) started its own testing programme earlier this month after the FAA began test flights in June.

EASA has maintained that clearance by the FAA will not automatically mean the plane is considered airworthy in Europe.

“Once the FAA and other regulators have determined the Max can safely return to service, it will be one of the most thoroughly scrutinised aircraft in history, and we have full confidence in its safety,” Boeing said.