EmailKid

Mission not accomplished.

LarryJ

In the memory items (completely quickly from memory) in both the UNRELIABLE AIRSPEED and STABILIZER RUNAWAY checklists are steps to disengage the autothrottles. This keeps you from getting into such a high-speed condition that you can't manually operate the stabilizer without unloading.

In the memory items for STABILIZER RUNAWAY is a step to use the stab trim cutout switches to stop the runaway. This stops the runaway before it gets to the full nose-down position that, coupled with excessive airspeed, puts you in a situation where unloading is needed to manual trim the stabilizer.

Neither of the accident crews properly applied the existing emergency procedures and their failure to do so made their situations much more difficult to handle.

The primary electric trim switches override MCAS activation and are fully functional for returning the stabilizer to a trimmed-state after each MCAS activation. The Ethiopian Captain did this through 21 MCAS activations which would have taken roughly 2:30 to 3:00 minutes. This isn't a "procedures", it is what a pilot does everytime the airplane he's flying becomes out of trim. It happens many dozens of times on every flight.

My response is that they never should have allowed the airspeed to reach 390 knots; about 140-180 knots faster than they should have been at that point.

The nose-down moment from the full nose-down stabilizer at 390 knots far outweighs the nose-up moment produced by the engines at climb power. You are much better off with low airspeed and low engine thrust.

That is an opinion based on the facts that have been released up to this point. If new information is released then the opinion may change.

Certification standards are the minimums. Manufacturers exceed these minimums in most areas.

Aircraft systems fail, sometimes in completely unexpected ways. When they do, us pilots have to find a way to address the problem and safely land the airplane.

The MAX was grounded (by the FAA) when the Ethiopian jackscrew was found in the full nose-down position. That established a strong link to the Lion Air accident before the unscheduled MCAS activation had been confirmed from DFDR data. Boeing had already sent information to operators, reminding crews of the proper existing procedures and describing additional accompanying symptoms, and started working on software changes.

The fact that Boeing had decided to make changes after the first accident does not mean that the original design did not meet certification standards. If it did not, the fleet would have been grounded months earlier. As of today, there still hasn't been any information released indicating that the original design failed to meet certification standards. Once the accident investigations are complete, a review of the certification standards may be undertaken.

DenverBrian

Mission accomplished.

84fiero

No, that's not what I'm referring to. Boeing thought the AOA disagree alert would operate in all cases (i.e., regardless of any optional features). This was not the case and Boeing was not aware of this fact until several months after deliveries began. Again, it goes to Boeing's thoroughness in its review processes to have not discovered that a feature did not operate as intended.

(And the option was for an AOA indicator.)

https://www.nytimes.com/2019/05/05/b...ing-light.html

More news, none of which is particularly confidence-boosting...

Pilots union to Boeing: 'Inexcusable' to blame pilots for 737 Max crashes

FAA says there could be delay in Boeing 737 Max software fix

The following is not about the MAX specifically, but an interesting read regarding issues within the FAA when it comes to oversight in general, which has been questioned regarding the MAX as well:

Inspectors say FAA pressures them to ignore critical plane problems: "The flying public needs to wake up"

ian_btv

One simple question: if the MCAS system original design had connected to, and would correlate the inputs from both AOA sensors vs. one, would any of this have happened?

DanielW

From my limited understanding, no.

ian_btv

Boeing and the FAA need to identify the engineer(s) who implemented and management who signed-off on such a blatant violation of design standards - and logic.

Whoever ignored that redundancy is requisite to automated systems relying on mechanical sensor data - he or she does not deserve to be an engineer. How many hundreds, thousands, billions of such electro-mechanical links (or programming in logic circuitry) exist in aerospace engineering?

NO excuse - this is just plain stupidity.

HawaiiO

From reddit n youtube

Plato90s

That depends on the assumptions.

The question is this - what would the software do in the presence of conflicting information but at least ONE of which indicated an action threshold.


In a well designed automation software, it would alert the operator to request action-response. Then it would wait for an additional threshold (critical condition) before deciding to kick off automated action in the absence of operator-response. That means MCAS software would take AoA data as well as stall-warning data at the same time. AoA would be the action-threshold (risk) and the stall-warning would be the additional threshold (critical condition). In the presence of conflicting AoA data, no action would be taken unless stall alarms went off.

When it comes to the Boeing design team, I think it's certain that the first response (alert pilots) would NOT be triggered because the primary design criteria of MCAS appears to be absolute secrecy. That is to say, it's deliberately designed to be hidden from the operator, in essence malware hiding itself from audit.

Given that intent, I think that the MCAS software would have triggered even if there was AoA data conflict because a software team which created this package would have opted for pre-emptive action as the only way to maintain secrecy.



So my answer is... dual AoA input would still have led to the same outcome because the MCAS software design and QA teams were fundamentally less concerned about safety compared to Boeing's time-to-market needs.

USA_flyer

That's a lot of inventory/cash sat right there.

COSPILOT

Even the CEO of Boeing admits knowledge and mistakes in how this was handled, yet some are defending Boeing as though they are perfect. I'm beyond confused as to why some think this is ok.

https://www.cbsnews.com/news/boeing-...orah-odonnell/

LarryJ

Who said it was ok?

COSPILOT

Is that a serious question? I respect your views as I do with my fellow pilot friends, but trust has been lost, and Boeing screwed up. Here I am as a private pilot and I get nervous flying into COS from the south, with memories of what happened back in 91 with flight 585. I love and hate Boeing at the same time. Unless I misunderstood you and a few others, I was under the impression that the airplane is perfectly fine, and shame on the pilots for not dealing with it properly. I have dead friends (5 of them) that crashed in Sitka, AK many years ago. One month prior the owner installed new Garmin 430's in his 421. Thousands of hours of flying for him, and I was supposed to be on the airplane but I backed out for personal reasons minutes before departure. I will never know if me being onboard would have prevented the crash, or if I would have been victim # 6. Both accidents hit me personally, and as such I take flying a personal airplane or commercial very seriously.

I think and agree that you do as well, but sometimes the "blame the pilot and not the aircraft" doesn't sit well with me. The MAX has a flaw via software that was never communicated to anyone, and for that I will never forgive Boeing, despite my love of Boeing from the time I was a young child.

84fiero

+1

LarryJ

If that's what you think, that you most certainly have misunderstood me.

Two completely separate issues.

1. Why did the unscheduled MCAS activations occur?

2. Why were two of the three properly trained and experienced crews unable to successfully land after the unscheduled MCAS activations?

The media, and almost all of the posters in these threads, are only interested in the first.