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The MAX had the MCAS installed to make it so that pilots could operate it under the type certificate of a 737. Otherwise, the plane would behave differently and
by wheaties 6y ago
The MAX had the MCAS installed to make it so that pilots could operate it under the type certificate of a 737. Otherwise, the plane would behave differently and would require retraining. What he's probably saying is there is nothing wrong with the plane's design without the MCAS. Financially, the 737 MAX wouldn't be a success that way.
- phkahler 6y ago>> What he's probably saying is there is nothing wrong with the plane's design without the MCAS. That is a common IMHO misconception. Since the new version with "fixed" MCAS requires additional training, it does not follow that MCAS exists simply to avoid retraining and non certifying it the same. In that case, Boeing should have simply dropped MCAS and did the certification and training. Instead they opted for the near financial disaster and disruption to their supply chain AND failure to avoid additional training. I suspect MCAS is covering for a very bad corner case in the flight dynamics.
- weaksauce 6y ago> I suspect MCAS is covering for a very bad corner case in the flight dynamics. yeah, much larger, stronger, and more forward positioned engines so the thrust leads to pitch up stalls in worst case scenarios.
- AnssiH 6y ago> I suspect MCAS is covering for a very bad corner case in the flight dynamics. I cannot judge the severity, but it covers for rule 14CFR §25.203(a) "Stall characteristics", see http://www.b737.org.uk/mcas.htm#background http://www.b737.org.uk/mcas.htm#background
- phire 6y agoYour suspicion is correct. FAA rules require on all planes that the control stick takes more and more pressure to pull back as the plane approaches stall. The 737 MAX doesn't meet this requirement, apparently it gets easier to pull the stick back as it approaches stall due to engine nacelles. This is what MCAS fixes, as the plane approaches stall, it adjusts trim to provide that extra back-pressure on the stick. No amount of additional pilot training will allow the plane to fly without MCAS, because this is a hard rule and it's not certifiable without it.
- cmurf 6y agoThe idea this deficiency can be masked by software is perverse. These parts of the regulations need to be true without electrical power. They're supposed to be a function of aerodynamics. This is only superseded in absurdity by the fact there are two switches to disable the stabilizer trim motors, thereby making the airplane no longer airworthy while in flight.
- msl 6y ago> These parts of the regulations need to be true without electrical power. How would you make that happen in a fly-by-wire airplane? In fact, how would you implement it at all in a digital fly-by-wire system without software? If you feel that using software to control an airplane is perverse, you might want to avoid flying.
- cmurf 6y agoThe 737 is not fly by wire. Airbus fly-by-wire have an alternate law mode where yoke input has matching control surface deflection, just like cable or hydraulic planes. I did not say no software anywhere ever. I said using it to mask aerodynamic deficiency is wrong. These are transport category aircraft. Not fighter jets. Positive static and dynamic stability is required. All of this is reviewable. Is the software?
- phkahler 6y agoThanks! That's the first I've heard what the actual problem was. Reducing pressure instead of increasing would make the controls inherently unstable.
- phire 6y agoIt's only right at the edge a stall condition, under most normal situations the controls are stable.
- cashsterling 6y agoIt is important to note that the MCAS was implemented on the MAX because the larger engines, and larger possible thrust vector further away from the planes center of mass, make it much easier to flip the plane over. The MAX is a bad aeronautical design that Boeing made more "controllable" through additional control system engineering. Problem is, the additional control system engineering was pretty bad.
- Judgmentality 6y ago> The MAX is a bad aeronautical design that Boeing made more "controllable" through additional control system engineering. Problem is, the additional control system engineering was pretty bad. Yeah, it's really frustrating that the solution was already a band-aid, and they didn't even bother to do that properly so they covered up what was questionably fraud (the lazy way of not getting a new certification) with what was unquestionably fraud (lying about the MCAS system). What's really sad though is it exposes just how defanged the FAA has become over the years, so now who the hell do we rely on to tell us what's safe for aviation?
- lamontcg 6y agoYeah the 737MAX should have been an entirely new airframe and not been a 737 at all.
- dboreham 6y ago757
- CydeWeys 6y agoThe 757 is long dead. They stopped manufacturing it in 2004. The real answer was the 797, which Boeing scrapped in favor of the 737 MAX.
- dboreham 6y agoMy point is that the 757 was the replacement for the 737, to accommodate high bypass engines. So we are a very long way down this road.
- rurban 6y agoWithout the MCAS the plane would stall. Which would lead to much more accidents than without MCAS or with the broken MCAS as we have now.
- marshmallow_12 6y agoI understand MCAS is only necessary when performing the most extreme, emergency maneuvers. Even then a good pilot would cope without it.
- rurban 6y agoNot as I understand it. It was installed because of the Airbus accident in the South Atlantic. An extreme case, yes. But with the engines moved back, the plane has the natural tendency to stall. Which is very common.