The US Federal Aviation Administration (FAA) has issued an 'emergency airworthiness directive' on about 250 Boeing 737 Max aircraft in the aftermath of a deadly Lion Air crash.
The late October crash off the coast of Indonesia killed all 189 on board.
The FAA directive follows a bulletin from Boeing to airlines stating investigators probing the crash had found that one of the "angle of attack" sensors on the brand-new Boeing 737 MAX jet had provided erroneous data.
"We are issuing this airworthiness directive because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design," says the FAA.
Experts say the angle of attack is a crucial parameter that helps the aircraft's computers understand whether its nose is too high, relative to the current of air - a phenomenon that can throw the plane into an aerodynamic stall and make it fall.
Some modern aircraft have systems designed to correct the posture of the aircraft automatically to keep flying safely.
Erroneous readings can in some circumstances cause 737 Max aircraft to point the nose down sharply to keep air under the wings and avoid a stall, a person briefed on the matter told Reuters.
The FAA said the order is effective immediately and covers 45 aircraft in the US operated by carriers including Southwest Airlines, United Airlines and American Airlines Group.
Newshub. / Reuters