Dennis Muilenburg wanted to be "the world's best aeroplane designer", he once told a reporter. Growing up milking cows on his father's farm in Sioux County, Iowa, he earned a coveted place studying aerospace engineering at Iowa State University, where a scholarship named after a former Boeing chief executive won him an internship with the world's largest passenger aircraft manufacturer. That launched his 34-year one-company career and led to his appointment as CEO in 2015.

But now he stands accused of helping precipitate the biggest crisis in Boeing's 103-year history and of a faltering response which may deepen the company's