In late 2018 and early 2019, two aircraft were lost in near identical accidents, off the coast of Indonesia and outside the Ethiopian capital Addis Ababa.
A total of 346 people were killed. Both crashes were caused by flawed flight control software, which ultimately forced the planes into catastrophic dives, despite the best efforts of the pilots.
Getty Images Ethiopian Airlines Boeing 737 Max 8 plane crashed in March 2019Getty Images
All passengers and crew perished after the Ethiopian Airlines Boeing 737 Max 8 flight crashed in 2019
Those incidents led to the grounding of the global 737 Max fleet for more than 18 months while the problem was rectified and further safety checks were carried out. The head of the FAA subsequently described the design as "the most scrutinised transport aircraft in history".
However, since the 737 Max came back into service, there have been a number of high profile problems with the programme, including electrical faults and quality control issues.
Safety campaigners have also expressed concern about the number of reported malfunctions aboard aircraft that have gone into service.
In December, Boeing called on airlines to inspect rudders on their aeroplanes, after a bolt was found to be missing on one aircraft. It said it was acting "out of an abundance of caution".
