GLOBAL ATTENTION FOCUSES ON SENSORS THAT CAN PITCH AIRCRAFT DOWN.

In the aftermath of two crashes involving Boeing 737 Max 8 aircraft, global attention is centring on an anti-stall system called the Manoeuvring Characteristics Augmentation System (MCAS).

The system was introduced on the aircraft — in service since May 2017 — because of design changes. According to The Air Current online news site, Boeing moved the engine slightly forward and higher up on the Max 8 and extended the nose landing gear by eight inches.

This made the plane 14 per cent more fuel efficient but it also changed how the plane handled — it tended to pitch up.

If a plane pitches up too high it will stall.

To address this, Boeing added the MCAS system which is constantly being fed data from two devices called angle-of-attack sensors located on the plane’s nose. The system is supposed to kick in when it senses the plane is about to stall and make adjustments so that the nose points downward.

But the new Boeing planes, it is feared, are going into emergency mode when there is no emergency.

A preliminary report released by local authorities after the Oct. 29 wreck of Lion Air Flight 610 — which went down off the coast of Indonesia, killing all 189 people on board — notes that the angle-of-attack sensor was sending erroneous readings throughout the short flight that day.

As the aircraft made its initial ascent, the sensor insisted the nose of the plane was too high and the MCAS kicked in, sending the plane downward as the pilots struggled to force it back up.

“Black-box data released by Indonesian investigators showed that the pilots were pulling back on the control column, attempting to raise the plane’s nose, with almost 100 pounds of pressure before they crashed,” the Washington Post reported.

Though the preliminary report stressed that the investigation was ongoing and did not assign blame for what happened, the crash raised questions about whether airlines and pilots had been trained on all the 737 Max’s software features.

The Federal Aviation Administration issued an emergency notice to all airlines that fly the aircraft, warning them that faulty sensor inputs “could cause the flight crew to have difficulty controlling the airplane,” leading to “possible impact with terrain.”

Pilots are trained to use a procedure to halt such dives, but Bloomberg reported that three pilots’ unions in the U.S. highlighted what they said was a lack of information provided by Boeing on the new system on the 737 Max 8.

Boeing is being sued by the families of victims of the Lion Air disaster over the plane’s allegedly faulty software.

The similarities between the Lion Air crash and the Ethiopian Airlines disaster are striking.

Both flights crashed within minutes of takeoff.

Both flights struggled to gain altitude.

Both flights ascended and descended several times before nosediving. In the case of Lion Air’s 12-minute journey, the plane pitched downward more than two dozen times before its final, deadly plunge.

The 737 Max 8 is the newest version of Boeing’s popular single-aisle airliner, which was first introduced in 1967 and has become the world’s most common passenger jet.

The 737 is the bestselling airliner in history and the Max, with its more fuel-efficient engines, is a central part of Chicago-based Boeing’s strategy to compete with European rival Airbus.