bhunt

Down the road once they do have a fix. Is public still going be scared to fly these birds? (I personally have no issues flying them now that pilots should know what to do.)

Probably wont effect United much but could hurt Southwest.

LarryJ

When you're hand-flying an airplane you are trimming frequently. Even more so in a transport jet as you are operating over a much wider range of speeds and configurations than smaller, slower airplanes. As conditions change, the nose either starts dropping below where you want it or it starts rising above it. You react by holding pressure to keep the nose in the desired position then re-trim to remove the pressure. This reaction is a normal part of hand-flying an airplane and should be an automatic response to an out-of-trim condition.

With what we know about the Lion Air accident, this is what the pilot-flying would have experienced.

The Captain's stick shaker (noisy) activated at liftoff and continued throughout the flight. When flaps were retracted the MCAS system would have begun to activate.

MCAS trims nose-down (up to 10 seconds or until the pilot activates the electric trim). The pilot feels the nose getting "heavy" and applies nose-up trim to return the airplane to a trimmed state. Nothing changes for five seconds...

MCAS trims nose-down (up to 10 seconds or until the pilot activates the electric trim). The pilot feels the nose getting "heavy" and applies nose-up trim to return the airplane to a trimmed state. Nothing changes for five seconds...

MCAS trims nose-down (up to 10 seconds or until the pilot activates the electric trim). The pilot feels the nose getting "heavy" and applies nose-up trim to return the airplane to a trimmed state. Nothing changes for five seconds...

After three, maybe four, cycles the pilot should notice that everytime he trims the nose back up the airplane is trimming it back down. This is a stabilizer runaway. He can continue to counter the MCAS activations with his electric trim indefinitely or accomplish the stabilizer runaway procedure which will disable the system for the remainder of the flight.

The procedure is; 1. Grasp control wheel firmly. 2. Disconnect Autopilot (it's already off or MCAS wouldn't be operating) and autothrottle. 3. Stab Trim switches to Cutout.

AoA Disagree messages, or in-depth knowledge of MCAS , doesn't really help because you're busy controlling the airplane and don't have time for detailed thought on system interaction. That would come later when you're writing up the problem in the logbook for maintenance to fix. You fly the airplane. The key factor in identifying a stabilizer runaway is the repeated, or increasing, abnormal need to retrim.

Here's an article from the Aircraft Owner's and Pilot's associate which talks about this issue.

https://www.aopa.org/news-and-media/...pilot-training


I believe that's a bad assumption. If the Speed Trim System (STS) caused a runaway it would also be temporarily cancelled by electric trim application, and also by opposite yoke inputs, and then would start up again. It's possible that a runaway stabilizer would present in a constant, unstoppable (by electric trim or yoke movement) runaway but there's no reason to believe that is the only way it could present.

I have been an airline pilot for 29 years. I have flown nine different airliner types. I have never flown an airplane with an AoA indicator. AoA indicators are common in military aircraft but relatively rare in civilian aircraft.

s0ssos

Can you help us by listing some of those, to get an idea?

spin88

And the first hit....

Garuda Airlines (Indonesia) cancels Order for 49 MAX, saying they have "low confidence" in the airplane.... https://www.washingtonpost.com/news/...=.68d185aa3def

First of many I would expect to be coming....

And the MAX10 is the worst dog of them all, and its not even launched.

BF263533

Just saw this on the late night news. From a public relations standpoint it makes United look cheap and risky. From a legal standpoint, in the unfortunate situation of an accident, it raises the issue that United was negligent. These safety features would probably have prevented the 737 mAX disasters. If you want to certify the plane with a common rating, I would think that you would want a backup warning system where there are materially different operational characteristics that must be compensated for with software.

Does anyone know the extra cost?

mduell

The FCC only uses the AOA sensor sensor on it's "side" (left or right) and FCC alternates per flight assuming you don't power down between them; MCAS slaves off the FCC side. To have MCAS reading both and comparing them would add additional complexity to at least MCAS and possibly the FCC.

Critical is a layman's term that does not sufficiently differentiate between several important levels; it is not a recognized design assurance level. MCAS is DAL C, Major: Failure is significant, but has a lesser impact than a Hazardous failure ... or significantly increases crew workload (safety related)
STS, which can also command electric trim changes, is also DAL C and on a single input sensor at any given time.
They could gold plate everything to DAL A, never finish development of the aircraft, and nobody could afford to buy it...

The design changes widely being armchair quarterbacked are tremendously more complex than the well known trim runaway procedure.

EWR764

lhrsfo

Garuda has many issues and I have no doubt that they are using this as an opportunity to get out of a contract they regret signing.

Strangely, Airbus just had a cancellation from Avianca, so they may well have some spare capacity in the next couple of years for an neo order - I just don't think it will be from Garuda.

dinoscool3

JimInOhio

Just a hunch.... we'll never see the MAX10.

EWR764

AOA indicators are installed for procedural reasons, primarily where airlines conduct, as a matter of policy, manual approaches in instrument conditions (e.g., HUD-assisted CAT III approaches). In visual flying, or autoland approaches, it's of minimal utility, unless UA decides to start doing carrier landings. United's 737s don't have HUD either; does that make them unsafe, too?

Bear96

I disagree airlines who did not get this option installed initially were negligent. It appears that Boeing marketed these planes as perfectly safe without that option. (In fact, Boeing was still claiming that even after the second crash.)

What industry standard did they violate - failure to predict the future about the failure of a system they likely did not have full information about?

Besides, you really cannot have negligence without damages. UA didn't cause any proximate damages to anyone by not ordering this option.

IADFlyer123

CNN reporting this morning that pilots training to transition from regular 737s to 737 Max were asked to take a self-guided learning lesson - https://www.cnn.com/2019/03/22/us/ma...ntl/index.html

These are US airline pilots. If this is even remotely true, and the training doesn't cover MCAS, then it should probably put to rest the claim that US pilots are trained better than international pilots and hence know how to operate the 73MAX.

Here are a few shocking quotes :

MarkyMarc

$80K for AoA disagree indicator. Happened to catch this on CBS Morning News as I was walking out the door.

https://www.cbsnews.com/news/boeing-...r-malfunction/

milepig

At this point, even if UAs birds are 100% safe and the pilots are perfectly trained, the optics that they chose to not pay something safety related are horrible and UA has some 'splainin to do.