On November 5,the Indonesian transportation-safety committee called on Boeing and the US National Transportation and Safety Board"to take necessary steps to prevent similar incidents,especially on the Boeing 737 Max,which number 200 aircraft all over the world,"according to a statement.

Boeing has delivered 219 Max planes – the latest and most advanced 737 jets – since the new models made their commercial debut last year with a Lion Air subsidiary. Boeing has more than 4500 orders for the airliners,which feature larger engines,more aerodynamic wings and an upgraded cockpit with larger glass displays. The single-aisle family is Boeing's biggest source of profit.

Aircraft and engine manufacturers routinely send bulletins to air carriers noting safety measures and maintenance actions they should take,most of them relatively routine. But the urgency of a fatal accident can trigger a flurry of such notices.

After an engine on a Southwest Airlines plane fractured earlier this year over Pennsylvania,killing a passenger,CFM International issued multiple bulletins to operators of its CFM56-7B power plants.

Aviation regulators such as the US Federal Aviation Administration and the European Aviation Safety Agency often follow such actions by mandating that carriers follow the bulletins.

Pilots raise and lower the nose of Boeing jetliners by pushing and pulling on a yoke in the cockpit,which controls panels at the tail known as elevators. In addition,a system known as elevator trim can be changed to prompt nose-up or nose-down movement.

The angle of attack readings are fed into a computer that in some cases will attempt to push down the nose using the elevator trim system. In the early days of the jet age,the elevator trim system was linked to several accidents. If pilots aren't careful,they can cause severe nose-down trim settings that make it impossible to level a plane.

Such an issue arose in 2016 at Rostov-on-Don Airport in Russia when a FlyDubai 737-800 nosed over and slammed into the runway at a steep angle,according to an interim report by Russian investigators. That case didn't involve the angle-of-attack system. One of the pilots had trimmed the plane to push the nose down while trying to climb after aborting a landing,the report said. All 62 people on board died.

Bloomberg with Reuters