At the centre of the mess was the MCAS which was a software system installed on the Max by Boeing to compensate for the Max having larger engines than its predecessors in the 737 family of airliners. Those larger engines changed the way the aeroplane responded to its controls, requiring a software system to keep it within certifiable limits.

Patrick Ky, chief of EASA, said in a statement: "EASA's review of the 737 MAX began with the MCAS but went far beyond. We took a decision early on to review the entire flight control system and gradually broadened our assessment to include all aspects of design which could influence how the flight controls operated. This led, for example, to a deeper study of the wiring installation, which resulted in a change that is now also mandated in the Proposed Airworthiness Directive."

Ky added: "We also pushed the aircraft to its limits during flight tests, assessed the behavior of the aircraft in failure scenarios, and could confirm that the aircraft is stable and has no tendency to pitch-up even without its MCAS software."

A spokesperson for EASA clarified that the Max's MCAS "is necessary to meet the safety regulation and obtain the necessary safety margins. However, when it is lost (failed and inoperative), an averagely skilled and trained crew can safely fly and land the airplane".