Originally Posted by
Less Hair
What possible legal consequences concerning certification would it have to call MCAS some "anti stall" device? It feels like all that spin doctoring concerning the fine print wording might somehow be legally motivated?
The phrase "anti-stall" falls into the much the same category as "unstable." It is not a defined term for the purposes of the aircraft certification. While we can use it generically for any system or device that helps in the prevention of or recovery from stalls, it does not correspond to any particular certification requirement. There
are requirements for stall warning devices and handling characteristics approaching and during a stall that are spelled out in detail in FAR Part 25, and it is those requirements that Boeing will point to when they explain why MCAS was needed.
In particular, FAR Part 25 make frequent references for the requirement that "the stick force curve must have a stable slope" in various flight regimes and that approaching a stall the "longitudinal control force must be positive up to and throughout the stall." The requirement for a "stable slope" in particular is what drove the need for MCAS.