Ryanair Boeing 737-800 (EI-CSV), marked Nykoping, takes off from London Luton Airport, England. The 737 horizontal stabilizer is the subject of an FAA inspection order. Wikicommons/Adrian ...

When activated, it makes small automatic adjustments to the horizontal stabilizer to counter pitch-up tendencies.

Boeing and Shanghai Aircraft Manufacturing Company (SAMC) signed a 10-year contract to manufacture 737 horizontal stabilizers on Sept 21. This is the largest and longest contract agreement between ...

Another issue was that the MCAS system was originally reported to the FAA as being capable of moving the rear horizontal stabilizer in increments a maximum of 0.6 degrees.

Regulators grounded the global Boeing 737 MAX fleet in March 2019 after two crashes in less than five months—Indonesia’s Lion Air Flight 610 and Ethiopian Airlines Flight 302—took 346 lives.

Like the original flaw that led to the plane's grounding, the new issue involves the uncommanded movement of the horizontal stabilizer, the little wing near the tail that moves the plane up or down.

MCAS controls the large horizontal wing on the plane’s tail known as the stabilizer, while the pilot controls smaller flaps or “elevators” on the stabilizer.

Boeing 737 MAX requires MCAS to achieve required feel forces. MCAS is not an anti-stall measure in primary as widely portrayed.

A minor change in Boeing’s 737 MAX manufacturing process that was insufficiently vetted caused an electrical system problem that on Friday temporarily grounded more than 60 of the aircraft ...