How bad is the handling with that system inoperative? The need for this came from adding bigger engines to a small airframe, which required putting them too far forward so they'd clear the ground.
My limited, layman understanding from the assorted coverage and posts by people who seem to understand this thing is that almost all the time the bigger, more forward engines do not cause a problem and MCAS doesn't have to do anything. It is just that on those very rare occasions when you get into a situation where it does make difference, MCAS helps you recover safely.
So, if the system can detect a problem with the AoA data and lock out MCAS, and tell the pilots that MCAS is disabled (and the pilots understand that this means some protection is gone), they should be able to finish the flight safely with at most a need to avoid pushing any limits that might get it into a situation where they do need MCAS.
Only those very very rare situations where the plane both gets into a situation where it needs MCAS and it simultaneously has an AoA sensor problem would be a problem.
I think this is why they can get away without triple redundancy and majority voting on the AoA sensors for MCAS. Losing MCAS is not an "Oh my god we are going to die!" situation. It's a "fly more conservatively for the rest of the flight" situation.
MCAS was designed to trim the stabiliser down in a high AOA situation, to give the pilots a bit of extra downwards control authority and help them recover from a stall.
To compensate for flying with MCAS inoperative, pilots will need to manually trim down when recovering from a stall. I assume they will just train the pilots to always trim forwards when recovering.
The scales are too often tipped in favor of coddling pilots (handling too much for them), with the trade-off being that emergency checklists multiply and become longer - to handle situations where plane systems and sensors fail.
Just because I can handle a car, prefer manual shifting and electronic helpers rather irritate than help me, I would never dare to demand we shift control back to the drivers. In effect, I am /safer/ when oncoming traffic manages to stay in it's lane...
Agreed, that kind of computer control is helpful and good. The problem comes when either (a) those secondary/contingent systems aren’t built to the same standards (redundancy, fault tolerance, etc.) as the primary systems; or (b) their reasons for existence are to artificially alter the flight characteristics of the plane, for no other reason than to make the plane fly “like another plane” or in a more familiar way — so the perceived aviation experience is effectively an abstraction, and a leaky one at that.
I’m not against abstracting away some of the flight characteristics, given that in doing so, proper due diligence is done to make the resulting system reliable and fault-tolerant.
Sounds like the expense they were trying to avoid if the plane were reclassified. Is the plane now going to fall under a reclassification?
It makes me wonder... if all planes had 2 Angle of Attack sensors, why was the disagree indication an extra option?
Was it almost pure price discrimination on the part of Boeing? A $4 light/buzzer for equipment, wiring and firmware already present, but only wired in for clients willing to pay an extra $10k per plane for the safe version?
A $4 light/buzzer for equipment, wiring and firmware already present, but only wired in for clients willing to pay an extra $10k per plane for the safe version?
Nope, EICAS literally a warning message which is just text on the LCD.
In at least one other case I vaguely recall, monitoring two sensors required bus bandwidth that was unavailable without a physical refit of cabling or electronics, so that could well have been the issue with AOA sensors and MCAS. I have no knowledge either way.
But my question was more like this: If it cost, say, $10k to buy the option, how much did it cost Boeing to actually enable it? If it was $8k, ok, but if it was $8 or $80, then they're more culpable.
After a careful look it turned out it was cheaper for the company to put a bigger screen in both models, but as a plastic cover on top to make it look small.
It didn't compromise the safety though.
Overclocking brings up similar circumstances: The market may have been 50/50 for the low-speed and the high-speed versions of a chip, but the yield may have been 70, 80 or even 100% for the high-speed, but the manufacturers still wanted to create a low-end and a high-end market.
Oh please, they're not being scrapped. But a working airport is not a proper place to store large jets.
Which is what I said.
But a working airport is not a proper place to store large jets.
Short-term it's fine. If the expectation is that the MAX will be allowed to fly in a few weeks it makes sense to keep the airplanes at strategically chosen airports. This'll make it easier to bring them back into service. If the assumption is that the MAX will be grounded for a long period of time it makes more sense to stash them at a graveyard like Victorville.
A counterexample is Air Canada abandoning their financial guidance for the year as a result of the 737 Max issues: https://www.bloomberg.com/news/articles/2019-03-15/air-canad...
Southwest can more easily substitute any of their other aircraft, lease more non-max models, defer non-essential maintenance activities, and use any other crew to fill the holes. They fly all 737s.
I don't think their 737 non-MAX fleet can even make the trip from Halifax to Paris like the MAX fleet can.
And transoceanic birds need other safety features not required for standard continental fleets, like life jackets.
(Scroll down to see the graphics.)
The current version of that experience is (I think) available as an add-on to X-Plane 10 mobile: https://www.x-plane.com/mobile/
Without any passengers or baggage the IATA code VCV would not have been used at any point of their flights.
I have my doubts about the other 13 it currentlu shows around the world, especially the ones whose flight plan calls for landing far from where they start, like the Norweigian Air flight from Dublin, Ireland to New York, or the Globus one on the way from Russia to Hong Kong.
What's going on here? Airlines still working on getting their grounded planes to where they want them to sit things out?
Looks like by far the most of them are Southwest, flying from a variety of airports (Baltimore, Los Angeles, Oakland, San Jose, Chicago), which is what one would expect for a "move planes to storage" operation, but the destinations are also all over the map, too (Victorville, Burbank, Indianapolis, Houston, Dallas, St. Louis, Denver). Stashing a few at each of their smaller airports?
What happened is a series of failures; this video frames it perfectly.
Of course, you may have a long and uncomfortable conversation with your chief pilot regarding the nature and quality of your judgement, but every single pilot is supposed to make an informed and independent evaluation of each aircraft before every flight.
Apart from that, which may not have made much difference there is no overall difference in terms of safety or training that would have prevented the Ethiopian crash.
Ethiopian is a state-of-the-art operation with a modern fleet. Lion Air is a bit more questionable, but their 737 crash appears to have nothing specific to that airline or being based in Indonesia.
You may have other evidence of hazards, so might I. But the 737 MAX saga isn’t it.
Should we therefore ground and review all the planes?
Also, the autopilot uses stabilizer trim. If you turn stabilizer trim to cutoff, you have no autopilot. Also, the emergency airworthiness directive says it's possible a runaway continues even after stabilizer trim is set to cutoff: If runaway continues, hold the stabilizer trim wheel against rotation and trim the airplane manually.
Once there was a second crash, with stabilizer jackscrew in the full nose down position, it was untenable to allow the planes to be considered airworthy, for the very central reason that we don't completely understand what happened and how to avoid it.
The proper response in aviation safety is not to assume pilots are doing the wrong thing upon receipt of an emergency airworthiness directive. It's to assume they are following the directive. You don't just pretend they're morons and keep on subjecting the general public to risk, while you guess at what the problem is.
And we don't want that?
> You can drive your car without cruise control
Sure, because cruise control is there to allow me to be lazy, not to keep my car on the road.
The aircraft has handling deficiencies at high angles of attack due to the engines being mounted differently. The MCAS is there to correct this. It's this or redesign the plane. Only 2 things that could have helped: an angle of attack disagree light to warn the pilots of the issue, and to to retrain the pilots. The first was sold just as an optional package, the second was considered unneeded since Boeing treated the new plane as a perfect equivalent of its predecessor. Disabling the MCAS is not a fix and without it the plane is not certified to fly.
You can fly a plane without an engine if needed but just try certifying a plane with one engine under one wing.
It is shocking to me that the second crash happened, if they both turn out to be MCAS and stab trim sourced. How could you step into the cockpit of a 737-Max that day and not know about the MCAS issue and be primed to respond according to the checklist?
I have to add that I'd be happy to put myself or my family onto a 737-Max flown by a US-flag carrier (Southwest, American, United [Delta doesn't fly the -Max]), as I believe there's a significant variance in crew training worldwide.
It shocks me that the redundant angle of attack sensor and the "disagree" light is not standard equipment. Who is buying multi-million dollar airplanes and cares about the cost of an angle of attack sensor and a lamp? Not people that care about safety, that's for sure. I know the airline industry loves nickel-and-diming their customers, but safety equipment is a little more important than priority boarding and a checked bag. It is shameful that Boeing adopted that business model.
More on angle of attack sensors: https://www.flightliteracy.com/angle-of-attack-indicators/. If you fly GA, you should get one. Having a readout of the flight energy you have available is one of the greatest safety upgrades you can make.
U.S. based pilots have said they didn't know anything about MCAS or MCAS upset until the FAA issued an emergency airworthiness directive, AD#: 2018-23-51, expressed surprise and were critical to discover this after the fact. Years after the fact. And it took a crash.
A second crash, despite the issuance of the AD suggests the AD is somehow sufficient. Maybe we don't know the full range of possible MCAS upset behavior. Maybe we don't know if there are additional factors that contribute to surprise and confusion.
the MCAS caused almost crash the day before the first crash of the same plane - it was only that off-duty pilot who knew about MCAS and thus saved the plane. Yet the next day that plane flew again with an MCAS unaware crew. Looks like some systemic issue. Grounding of the planes would allow to correct the specific tech issue of MCAS. Whether the systemic issue is going to be corrected is yet to be seen.
What is a waste is pretending that wasted resources is the worst thing that can happen here when we have two fatal crashes being investigated.
Well, that put me my place. I'll hop right on another one tomorrow!