> MCAS is quite safe
A few hundred people who died as a result of MCAS would disagree. MCAS is not safe as currently implemented, or the 737 Max would still be flying.
A few hundred people who died as a result of MCAS would disagree. MCAS is not safe as currently implemented, or the 737 Max would still be flying.
MCAS on the other hand is basically a bad hack that was necessary for business reasons. It's a serious step backwards in safety from previous iterations, which has not happened with modern nukes.
Airplane certification is expensive for both manufacturer and airlines that might want to fly it. So there is a quicker process if you just make minor revisions, a reasonable compromise on the surface. Certification is so expensive and not having to retrain pilots is such a huge selling feature it creates a pressure to make planes that meet the same type requirements rather than design new airframes.
Boeing is all set to design a new airframe to replace the 737 that will be more fuel efficient and be built for today's point to point flights. Along comes airbus with the a320neo (new engine option) that kills the 737-800 on fuel efficiency and Boeing panics. They scrap 2020 plans for a 737 replacement and design the MAX. Now the problems mount. Fuel efficiency needs turbines that spin slower but have more surface area and are therefore larger. 737 is a low slung plane, dating back to hub and spoke flight concepts where the 737 might land places that don't have jetways. Since the plane is so close to the ground, Boeing has to move the engines forward so they can raise them. This generates more lift than previous 737s, but to meet same type requirements the plan has to be the same. Not meeting same type means they can't sell to airlines like southwest who only fly a single type and any airlines who do commit will have to spend training dollars, raising the total cost of operation without adding anything to the bill of materials.
Enter MCAS, a system designed to meet the same type regulation with disastrous unintended side effects. Side effects made much worse by the fact pilots don't know the system even exists since this plane is the same as every other 737 as far as they know.
I don't think the same type regulation should be scrapped since it would stop things like fuel efficiency gains during an airframe's lifespan, but there needs to be a same type minimum training and documentation that has to be done even if the only thing you change is thickness of the paint. If anything the definition of what meets same type should be slightly expanded allowing more flexibility in what can be changed. Combined with mandatory training for all subtypes (but still much shorter than different type training) the perverse incentive to make the plane behave exactly the same is removed. That leaves room for the better technical fix to win the day rather than the one that will meet the regulation. Training costs will go up some, but less than full different type certification.
There's a nasty rumor that Boeing agreed to pay Southwest $1 million per plane if additional training was required. That's a lot of money just on the Southwest contract. If any other airlines (e.g. Ryanair) demanded similar that's a huge chunk of money.
I see this entirely differently -- the FAA was being way too lenient/cozy with Boeing, and took their word that the airplane operated exactly the same (even if it didn't). This to me indicates that harsher regulations are needed, not less harsh ones! In what other industry do manufacturers self-certify such safety-critical machines?!
Relax regulations and we'll just start seeing more of those crashes that have killed so many airline passengers previously. It's a proven fact across all industries since time immemorial; companies don't make things safe out of the good of their hearts, and are OK with shockingly high body counts. Governments have routinely needed to rein in companies that were playing fast and loose with safety.
Place a random passenger into the cockpit of a modern commercial airliner without training and ask them to fly the thing safely and you'd probably have a 100% loss rate.
It retains no memory of being overridden by pilot input but will keep pitching down until cut-out of the loop or the aircraft exits what it thinks is the dangerous corner of the envelope. Unfortunately it often lacks the information to make that determination correctly, due to the poorly-designed sensor integration.
That sounds like something right out of the 'Catastrophic Failures' books we studied in uni.
This ultimately is not a training issue. Why was a system that can potentially plow the aircraft's nose into the ground utilizing only a single sensor without any redundancy in place? Boeing screwed up. Now both sensors will be used. Great, but sometimes 2 sensors fail. If pilots that operate these aircrafts are trusted with the lives of 150+ passengers, they should have an "easy button" to take complete manual control of the aircraft. My human sensors should trump any mechanical sensor(s) when my life is on the line.
Activating those switches cuts off electric trim and would completely deactivate MCAS. It can be done in seconds.
Are there other feedback mechanisms present that can interrupt that determination?
That appears to be the case in these scenarios. The MCAS doesn't perform the incorrect action continuously, it looks like initial corrective measures fix the problem until they suddenly don't.
And then what? How much longer will it take to manually move the stabilizer to a suitable position? How much time do the pilots have at under 7,000 ft AGL? Will the elevator have to be moved nose down to unload the stab before the stab can be retrimmed?
That's great...if they'd understood that the system was malfunctioning...but they had no such indication because their airline didn't pay for the optional "feature."