CApreppie

It looks terrible on United's part to be such a huge, international carrier and cheap out on some safety features that they probably could have bargained hard for to bring it under that $80K (assuming list price) especially since AA and WN ordered the warning light. Typical cheap United and typically bad PR/executive response.

I've flown on United's MAX 9 2x before the accidents.

LarryJ

MCAS is operational only when the autopilot is OFF. You don't takeoff with the autopilot on. The minimum autopilot engagement altitude on takeoff is 800' and it's actually easier to continue to hand fly it through the acceleration and clean up (gear and flaps).

The media keeps reporting that MCAS is a stall prevention system. It is not (though it might also have that affect). MCAS is Maneuvering Characteristics Augmentation System. Due to the aerodynamic characteristics of the engine nacelles, and higher engine residual thrust, the pitch "feel" is lighter at high angles-of-attack on the MAX than it is on the 737 NGs. MCAS adds a nose-down bias, through the application of nose-down stabilizer trim, to produce a heavier "feel" in these situations which more closely matches the pitch "feel", or maneuvering characteristics, of an NG in similar situations.

No. MCAS is only active when the autopilot is disengaged. Since, as you note, the purpose of MCAS is to match the MAX's maneuvering characteristics to those of the NG it is only necessary when the pilots are hand-flying. The autopilot doesn't care if it "feels" the same as other 737 models.

The procedure is not the "MCAS deactivation procedure". It is the "runaway stabilizer" procedure. A variety of systems, and failures, can result in a runaway stabilizer; MCAS is only one of them. Because an unchecked runaway stabilizer can quickly lead to a loss of control, you don't waste time trying to diagnose the reason for the runaway. If you have a runaway, you disable the electric stab trim which stops it. Let the mechanics figure out the cause of the runaway after you land. The runaway stabilizer procedure is the correct actions regardless of the underlying cause of the runaway. Since the autopilot also operates the trim (when it is on), the procedure has you disconnect the autopilot as part of the procedure because a failure in the autopilot could potentially cause a runaway. We're talking here specifically about a runaway caused by MCAS so, in that case, the autopilot must already be off by definition.


More bad reporting. The reporters are trying to report technical information that don't fully understand. The AoA display isn't a "safety feature" and it would not be helpful in dealing with an invalid MCAS activation.

The 737 has two options for conduction low visibility landings--called CAT II and CAT III landings. One option is through the autoland feature which uses the airplanes two autopilots, working together, to land in visabilities as low as 600 feet. The other option is the installation of a heads-up-display (HUD). With the HUD the Captain hand-flies the aircraft to landing using the data display on the HUD as he's looking out the window. This HUD option requires the AoA indicator display option; autoland does not. The airlines that have the AoA display option are the airlines that opted for HUDs for CAT II/III landings while the airlines without it use autoland.

EWR764

generaltao

narvik

I see this quite differently.
Something tells me that when all the dust eventually settles and some changes are [likely] made either voluntarily or mandated, the MAX might well be one of the safest planes out there.
The thorough scrutiny the MAX will now face will probably lead to exaggerated safety features and supplement pilot training not necessarily found in other planes.
Just my unscientific prediction.

fly18725

fly18725

Lux Flyer

This.

With everything that has come out the past couple weeks. I think the consensus for grounding should have shifted; at least outside the USA. It doesn't matter if MCAS was at fault for these crashes, there are serious questions about the regulatory approval process for the MAX airplanes. It's already known the FAA was given incorrect information for at least one system they used in their analysis and Boeing was given lattitude to do the analysis of numerous other systems. There's also been numerous statements by FAA engineers who were concerned about the amount of analysis being deferred to Boeing. This really raises the concern whether the FAA was focused on minimizing risk or was in bed with Boeing to try and promote their business interests even if it unintentionally impacts safety. IMO this plane is getting significant reevaluation by the FAA in order to allay concerns other countries may have.

kale73

DenverBrian

And I don't want Donald Rumsfeld anywhere near the testing and certification process either. @:-)

DenverBrian

No worries. You go fly the MAX for a year or two. Some of us will wish you well.

But I'd rather you be the guinea pig than me. And, given the relative rarity of the MAX for the next few years domestically, I think I can avoid it and let others "test" it for a while. @:-)

bman1002

I read on another forum that Southwest is sending their MAX planes to Victorville for storage. VCV is generally known for long term storage, so I guess WN knows they won't be flying these birds for a while.

fumje

Thanks for the additional explanation. ^

It sounds to me that, from the pilot's perspective in the moment, the thinking is, 'I have a runaway stabiliser — let me get the aircraft back under control manually now,' and that figuring out if it's the MCAS or XYZ or ABC isn't immediately important.

And extending that — while it certainly is hazardous to have an aircraft design that creates a runaway stabiliser condition with regularity, at least as things appear so far, it theoretically should have been possible for a pilot to rescue both of the crashed flights?

skidooman

narvik

Unlikely to encounter it on EWR-PEK.

Also, they are potentially grounded for "quite some time".