Regulators knew before crashes that 737 MAX trim control was confusing in some conditions: document

A Boeing 737 MAX 8 takes off during a flight test in Renton, Washington, January 29, 2016.

US and European regulators knew at least two years before a Lion Air crash that the usual method for controlling the Boeing 737 MAX’s nose angle might not work in conditions similar to those in two recent disasters, a document shows.

The European Union Aviation Safety Agency (EASA) certified the plane as safe in part because it said additional procedures and training would “clearly explain” to pilots the “unusual” situations in which they would need to manipulate a rarely used manual wheel to control, or “trim,” the plane’s angle.