[mchristen]

> The problem with the Max is that Boeing favoured the major airlines that wanted 2010s technology in a 60s airframe. But guess what, that doesn't work, in the same way you can't turn a Thunderbird into a Tesla by "just plugging a new engine".

No, the problem with the plane was that Boeing engineered a crappy solution to a problem they had.

There were 3 major problems that I am aware of.

1) A powerful(flight control wise) automated system that relied on one source of sensor data when multiple are available.

2) The switches that disabled the automated system also disabled all electronic control for the elevator trim, making it much harder for the pilots to recover from an out of trim condition.

3) The normal elevator controls are not enough for the pilot to overcome the out of trim condition so pulling back on the yoke as far as possible would not pitch the plane up enough to regain altitude.

The only way to recover from this type of situation is to momentarily pitch the plane further downwards to take stress off of the elevator trim so the manual controls are easier to operate with your hand. You would have to do that enough times to get the plane back into a stable position, this is not always possible when the plane is already at a low altitude.

[p_l]

Those problems started with Boeing wanting to keep 737NG type rating as a selling point.

Keeping the type rating means that they needed to avoid making completely new wings or significant fuselage changes, which would require a new type rating as well.

All of that led to fitting engines in a way that caused a bunch of aerodynamics problems, which led to crappy solutions.

The economic incentives started it.

[raverbashing]

You're looking at the first why, not at the deeper issues.

Why did they have issues with MCAS? Why did they even need MCAS again?

Because they tried to fit bigger engines onto a 60s airframe that is not fly-by-wire.

If the plane was FBW, no MCAS needed.

If the plane had a bigger ground clearance, no MCAS needed.

> The normal elevator controls are not enough for the pilot to overcome the out of trim condition

I don't think there is a plane where they are, they also move more slowly than the elevators.

[salawat]

This is incorrect. Fly-by-Wire makes minimal difference when the basic aerodynamics are flawed and non-compliant. Airframe certifiability is behavior based. You must meet a prescribed set of behaviors, while lacking any prescriptive misbehaviors. The idea is an airframe in it's minimally "assisted" state should demonstrate basic airworthy characteristics.

A plane should be airworthy even if the majority of it's automation has suffered a casualty.

[raverbashing]

> Fly-by-Wire makes minimal difference when the basic aerodynamics are flawed and non-compliant.

Yes, but you wouldn't need MCAS for maintaining longitudinal stability

> in it's (sic) minimally "assisted" state should demonstrate basic airworthy characteristics.

If that was the case the Max would not be certifiable, MCAS or not

[Aloha]

The 737MAX is airworthy without MCAS, it just flies differently than a 737 NG, hence why they added MCAS.

[msbarnett]

False. The MCAS exists to prevent stick forces from inverting as the nose pitches up towards the stall angle. If the stick forces invert, it becomes easier to continue into a stall angle than to move away from it. Commercial airframes are required to never exhibit this characteristic as a condition of certification.

MCAS was Boeing’s idea of a solution to this; command the stabilizers down to provide counter force against the stick, making it harder for the pilot to pull into the stall than pull away from it at every point.

Even if the 737NG had never existed and the 737MAX as it exists today were for some reason an all new design, it would need the MCAS counter-force to get certified as air worthy no matter how much new training pilots got. It (claims to) solve a fundamental airworthiness requirement; it is not a “737NG emulation feature” as some mistakenly believe.

[weaksauce]

They should be able to override the trim via thumb switch and then cut out the trim system once it’s trammed in. Mcas cuts out when the thumb switch is applied.