Maneuvering Characteristics Augmentation System (MCAS)
The Maneuvering Characteristics Augmentation System (MCAS) prevents stalls in specific flight phases and aircraft configurations.
It was developed and implemented on the Boeing 737 MAX‑8 and ‑9 because these aircraft are equipped with new engines which are attached to the wings higher and further forward than in previous models such as 737‑800. The engines of the MAX series are also heavier, provide more thrust and have a redesigned shape of the nacelles. All the modifications listed above cause an upward pitching moment especially during initial climb with maximum take‑off power. In order to meet the certification requirements, the 737 MAX had to be protected from the effects of such unsafe aircraft behaviour in flight by the introduction of a new MCAS system.