The night he became president, Allen jotted a series of resolutions into his diary. In addition to doing daily sit-ups: "Be considerate of my associates' views," "let others talk," and "make a sincere effort to understand labour's viewpoint". 

The company maintains a reputation for betting everything on new aircraft, from the humpbacked 747 to the more advanced, twin-engine 777 in the mid-90s. 

Years ahead of becoming Boeing's latest humbled and contrite CEO, Calhoun co-authors a manual for aspiring business leaders. 

Two plane crashes in Indonesia (2018) and Ethiopia (2019) interrupt decades of Boeing enjoying a reputation as an iconic manufacturer whose name was synonymous with engineering excellence. 

737 Max planes are grounded, and an internal reporting programme introduced to foster positive internal safety culture. 

Surveys showed many Boeing employees didn't trust the Speak Up programme. 

Muilenburg is ousted after downplaying design defects that killed 346 people when the Max's flawed software sent planes into the sea off Indonesia and a field in Ethiopia. 

After a decade on Boeing's board, Calhoun becomes CEO. 

Drawing a bright line between himself and his predecessor, Calhoun frequently emphasises making safety a top priority in the wake of the crashes. 

He claims to have assigned his best leadership team to monitor anomalies in every flight worldwide. 

Within a year, the Max's fuselage manufacturer, Spirit AeroSystems Holdings Inc, reports problems including mis-drilled holes in a cabin component and badly assembled fittings in the tail. 

A gaping hole opens mid-flight on the 737 Max. 

Using manufacturing jargon, Calhoun describes the incident as a "quality escape," which becomes catnip for TV comedians and internet memes. 

An FAA report describes "disconnect" between senior management and workers, some of whom fear retaliation for reporting safety issues. 

"Their priorities have been on production, and not on safety and quality," FAA administrator Michael Whitaker says. 

Boeing says it has responded by, among other things, giving mechanics more time to complete compliance sweeps and rewriting an incentive formula for employee bonuses to focus mainly on safety and quality metrics. 

Former quality control manager and whistleblower John Barnett found dead from a self-inflicted gunshot wound. 

"He was looking forward to having his day in court and hoped that it would force Boeing to change its culture," Barnett's family said. 

In one of the broadest management shakeups in its century-long history, Boeing looks for a new CEO and another chance to fix its culture. 

Alongside Calhoun, chairman Larry Kellner and head of the commercial aircraft unit, Stanley Deal, leave.