Updated MCAS ‘Safe’ Says MAX Technical Team

[Beefitarian]

Yes, it was intended to be funny. I believe most planes are still being landed by a person.

[jakeandelwood]

Sims are highly structured and time compressed scripts. There's no time or money for proficiency flying in the Sim.Even if there were, twice a year isn't enough to be proficient.

Different companies have different ways that they utilize the sim time, I'll give you that point. I disagree-twice per year comes around quickly. The sim should be a tool to keep you sharp, not bring you back from regression. It should never be difficult to follow the cue with the AP off anyhow.

First officer, "Wow, that's the hardest landing I've ever seen!"

Captain, "Yeah, I don't know why that happened, I have been practicing lots, just last week I was doing greasers in a 172."

Almost funny. Most airline guys are hand flying the portion below mins, are they not?

"Hand flying the portion below mins"
So they are maintaining their hand flying skills by flying the last 10 seconds of the flight? Wow, that's a lot of hand flying.

[C.W.E.]

"Hand flying the portion below mins"
So they are maintaining their hand flying skills by flying the last 10 seconds of the flight? Wow, that's a lot of hand flying.

[ayseven]

I had an autopilot once. I turned it on twice. I cannot actually visualise flying but not flying. But I guess if it makes things BETTER, it's good. I always thought hand flying was the easy part if being a pilot, but i guess I've been wrong.

[ReserveTank]

Sims are highly structured and time compressed scripts. There's no time or money for proficiency flying in the Sim.Even if there were, twice a year isn't enough to be proficient.

Different companies have different ways that they utilize the sim time, I'll give you that point. I disagree-twice per year comes around quickly. The sim should be a tool to keep you sharp, not bring you back from regression. It should never be difficult to follow the cue with the AP off anyhow.

First officer, "Wow, that's the hardest landing I've ever seen!"

Captain, "Yeah, I don't know why that happened, I have been practicing lots, just last week I was doing greasers in a 172."

Almost funny. Most airline guys are hand flying the portion below mins, are they not?

"Hand flying the portion below mins"
So they are maintaining their hand flying skills by flying the last 10 seconds of the flight? Wow, that's a lot of hand flying.

You can make sport of my opinion if you'd like. Modern (and I mean from the 90's onward especially) airliners are easy to fly and don't require copious hours of practice to fly well. If you need it, I question your general skills. If you aren't confident that you can follow a cue by hand if the AP fails, again I question your basic skills. You are supposed to have a handle on this before you fly big iron. The airplane isn't there for your personal training time. They are paying you to enter the aircraft with a proficient mindset, not to show up and hand-bomb it around.

There's a time and a place for everything. I hand flew many flavours of props for thousands of hours, and so did many of you. You shouldn't need confidence building exercises outside of the training environment.

[Eric Janson]

There's a thread running on Airliners about Pilots cancelling flights because the auto-pilot is INOP. WTF?

I get there's an issue with RVSM but if the company is happy with the extra fuel burn I'd be quite happy to fly below RVSM Airspace without an auto-pilot.

These days:-

-Aircraft Manufacturers can no longer build reliable aircraft.

-Engine Manufacturers can no longer build reliable Engines.

-Pilots can no longer fly their aeroplanes.

What a sad state Aviation is in.

[goingnowherefast]

There's a time and a place for everything. I hand flew many flavours of props for thousands of hours, and so did many of you. You shouldn't need confidence building exercises outside of the training environment.

These days kids are going to Jazz with 800hrs, never to really hand fly again. Gone are the days of 800hrs in the right seat of a charter Cessna 404 before being awarded the privilege of an right seat in an old King Air with a crap autopilot that sorta works, but nobody uses.

[jakeandelwood]

Different companies have different ways that they utilize the sim time, I'll give you that point. I disagree-twice per year comes around quickly. The sim should be a tool to keep you sharp, not bring you back from regression. It should never be difficult to follow the cue with the AP off anyhow.



Almost funny. Most airline guys are hand flying the portion below mins, are they not?

"Hand flying the portion below mins"
So they are maintaining their hand flying skills by flying the last 10 seconds of the flight? Wow, that's a lot of hand flying.

You can make sport of my opinion if you'd like. Modern (and I mean from the 90's onward especially) airliners are easy to fly and don't require copious hours of practice to fly well. If you need it, I question your general skills. If you aren't confident that you can follow a cue by hand if the AP fails, again I question your basic skills. You are supposed to have a handle on this before you fly big iron. The airplane isn't there for your personal training time. They are paying you to enter the aircraft with a proficient mindset, not to show up and hand-bomb it around.

There's a time and a place for everything. I hand flew many flavours of props for thousands of hours, and so did many of you. You shouldn't need confidence building exercises outside of the training environment.

It doesn't seem like there is a time and place for any of it in the airline world at all, the auto pilot goes on after rotation then comes off just before touch down. Where is this "time and place for everything" ? It's like your kid wanting to do math in their head because they want to stay sharp and you saying no, use the calculator, it's more accurate. This world is gotten itself into a sad state of affairs. What mr. Jansen said about canceling flights because of an inop auto pilot just sums it all up completely.

[valleyboy]

Unfortunately auto pilot is a no go item because of airspace, I guess they could dispatch the aircraft below 280 but I doubt in this day and age they would do that, especially since the computers are flying even in manual mode. This is a throw back to the classics and no "modem aircraft" would be dispatched without a functioning auto pilot. Like a dog chasing its tail. As I maintained, stick and rudder skills will eventually fade into oblivion. It's a simple fact of technology. Automatics do it better, we are still in the era of requiring a thinking warm body in the flight deck but even that will fade and AI will take over and short haul will be replaced by high speed vacuum tubes.

[ReserveTank]

It's like your kid wanting to do math in their head because they want to stay sharp and you saying no, use the calculator, it's more accurate.

I haven't met many people that are better than the computer. Case in point from one man's observation-There's a stack of flight logs that show up on the CP's desk every week because the captains try to out-math the calculator. Repeat offenders get the carpet dance and some get a boot to the rear.

This world is gotten itself into a sad state of affairs. What mr. Jansen said about canceling flights because of an inop auto pilot just sums it all up completely.

There's a thread running on Airliners about Pilots cancelling flights because the auto-pilot is INOP. WTF?

Generally, airline pilots don't CANCEL flights. That's an operational control decision. The crew can write it up and decide if they want to operate with an MEL on the AP system. These days, an airline crew must think twice before being released with MELs because it is a legally binding decision. If the cards are stacking against the crew, like they're getting tired, they have bad weather, and/or other MELs which require constant crew attention, the crew can decide that it's not the safest option for the flight. The system is overly litigious and doesn't forgive crews for their mistakes. The company is not going to help you if you bung up a flight related to an MEL. We just had a captain get knocked back to the right seat for "helping out." He agreed to dispatch the plane, they got busy in bad weather, exceeded an aircraft limitation, and the CP busted him back indefinitely. The captain was not a bad stick, either. Just not his day...but still no one defended him. That's what we are dealing with out there.

Who is the old feller on this board who keeps saying that they "never killed anyone by refusing to fly"?

[C.W.E.]

Who is the old feller on this board who keeps saying that they "never killed anyone by refusing to fly"?

Me.

I'm not old, just advancing in years.

[Gannet167]

I disagree-twice per year comes around quickly. The sim should be a tool to keep you sharp, not bring you back from regression.

So, in your books pilots should rotate and engage AP at lowest permitted altitude (paying customers deserve "safety") and only hand fly from mins to the runway. However, twice a year they get to practice in the sim and that will keep them proficient at hand flying, basic IFR cross check etc? If you think it's that easy to maintain the skills then surely it can't be a reduction in safety to (for the love of God) hand fly.

It should never be difficult to follow the cue with the AP off anyhow.

So, if it's never that difficult, how could it be such a safety issue to hand fly with passengers? This is a contradiction. You say passengers are paying for the highest level of safety so AP on all the time, yet you also so it should never be that difficult, in which case where's the safety issue?

If you need it, I question your general skills. If you aren't confident that you can follow a cue by hand if the AP fails, again I question your basic skills.

But, if we're so confident that pilots can follow "a cue", why the concern about using your hands with passengers? Again it doesn't make sense. It's either deathly unsafe, or so easy that the safety factor is a non issue, you can't have it both ways.

The a320 is one of the more automated and computerized fly by wire machines. Single engine, it cannot fly a non precision approach coupled to the autopilot. In addition, in some scenario is, you need to fly raw data. It's not a big deal, as long as you have some proficiency. If my family is on the plane, V1 cut, returning to land, need to hand fly an IFR approach, I sure hope the guy at the controls has been "hand bombing" around during the last few flights and tuned up on their skills.

You may be some aviation God who's skills don't fade but you'd be the exception. Having taught and done check rides on an awful lot of air force guys, even some of the best sticks get rusty after being out of the cockpit for a period of time. It's a simple human limitation of recency.

There's a lot better, higher risk items to attack if we're so paranoid about passenger safety. Long before I'd be concerned about a pilot hand flying I'd be worried about 100 other things, like how much sleep they got on the min time layover.

I propose that we add a requirement to hand fly an entire leg, raw data once per quarter. A precision and a non precision approach required. It'd be the best flight of your quarter. The FAA among other regulatory bodes have long identified basic skill fade as a large aspect of safety. If you get into trouble, there's another pilot there to help and you can always put the autopilot on if you're scared.

[goingnowherefast]

Why can't we hand fly the plane on a quiet calm morning departure from an out station with light workload? What about that calm arrival into a quiet airport somewhere with reasonable weather. Maybe brief the whole approach and fly off the gauges until minimums.

[jakeandelwood]

It's like your kid wanting to do math in their head because they want to stay sharp and you saying no, use the calculator, it's more accurate.

I haven't met many people that are better than the computer. Case in point from one man's observation-There's a stack of flight logs that show up on the CP's desk every week because the captains try to out-math the calculator. Repeat offenders get the carpet dance and some get a boot to the rear.

This world is gotten itself into a sad state of affairs. What mr. Jansen said about canceling flights because of an inop auto pilot just sums it all up completely.

There's a thread running on Airliners about Pilots cancelling flights because the auto-pilot is INOP. WTF?

Generally, airline pilots don't CANCEL flights. That's an operational control decision. The crew can write it up and decide if they want to operate with an MEL on the AP system. These days, an airline crew must think twice before being released with MELs because it is a legally binding decision. If the cards are stacking against the crew, like they're getting tired, they have bad weather, and/or other MELs which require constant crew attention, the crew can decide that it's not the safest option for the flight. The system is overly litigious and doesn't forgive crews for their mistakes. The company is not going to help you if you bung up a flight related to an MEL. We just had a captain get knocked back to the right seat for "helping out." He agreed to dispatch the plane, they got busy in bad weather, exceeded an aircraft limitation, and the CP busted him back indefinitely. The captain was not a bad stick, either. Just not his day...but still no one defended him. That's what we are dealing with out there.

Who is the old feller on this board who keeps saying that they "never killed anyone by refusing to fly"?

I'll agree with you there, while I don't fly commercially anymore I have gone the extra mile at my current job and used methods which are frowned upon by management to " get the job done and make everyone happy". Just to get shit on for doing so. I just don't bother anymore. The job just doesn't get done then. It's all about covering your ass I guess nowadays.

[AuxBatOn]

I haven't met many people that are better than the computer. Case in point from one man's observation-There's a stack of flight logs that show up on the CP's desk every week because the captains try to out-math the calculator. Repeat offenders get the carpet dance and some get a boot to the rear.

It’s very contextual. Sure an aircraft computer can fly more precisely than I can. But it cannot make decisions. If the Apollo computer didn’t have an override function, the Eagle lunar module would have crashed into boulders.

If you want to learn about optimal human-machine integration in aerospace vehicles (and how to maximize the machines’ and human strengths), read Digital Apollo. It’s about the development of the Apollo guidance system and the factors that influenced the design of the Apollo guidance computers. Some of the factors considered still affect today’s airliners design choices.

[geodoc]

As an aside, I came across an interesting article in The New Yorker with a deeper "pulled back" view than most that focuses (mainly) on the change in corporate culture at Boeing over the last 25 or so years.

https://www.newyorker.com/magazine/2019 ... nst-boeing

Or for audio of the article:

https://audm.herokuapp.com/player-embed ... 000813adc7

[pelmet]

Personally I will not go on this plane for several years, my personel feeeling

But you probably will fly on the 737 Super. My predicted new name for modified Max’s.

Unless Boeing gets sneaky and lumps it in the NG category.

[pelmet]

There's a thread running on Airliners about Pilots cancelling flights because the auto-pilot is INOP. WTF?

I get there's an issue with RVSM but if the company is happy with the extra fuel burn I'd be quite happy to fly below RVSM Airspace without an auto-pilot.

How long a flight? I did that once on a five hour overnight flight....not fun. Then again, the chief pilot(or was it future chief at the time) was snoozing away beside me. Best to get a block of airspace if you can.

I don’t think I’d take a jet on a long haul flight like that, especially away from base.

[valleyboy]

We all know it's up to the capitan to accept a deferred item. There are many reasons to decline a flight and possibly in this day and age it's more about safety and protecting your ass. Accept the aircraft you are putting your ass on the line if there is an incident. Yup -"giver" attitude is dying because you get no thanks for going above and beyond to get a trip done. You are more apt to get WTF were you thinking!

[W5]

Boeing’s fix tames the ‘tiger’ in the 737 MAX flight controls, say experts and critics

https://www.seattletimes.com/business/b ... -controls/

After months of intense scrutiny, even some of the harshest critics of the 737 MAX’s flight-control system believe Boeing’s software fix will prevent a recurrence of the scenarios that killed 346 people in the crashes in Indonesia and Ethiopia.

Boeing has redesigned the MAX’s new automated Maneuvering Characteristics Augmentation System (MCAS) that relentlessly pushed down the noses of the two aircraft on both crash flights. Though serious questions linger about the overall safety culture at Boeing that waved through MCAS’s original development and certification, U.S. airline pilots are almost ready to fly the updated jet.

“The hazard is designed out of it,” Capt. John DeLeeuw, chairman of the safety committee of the Allied Pilots Association (APA), the union for American Airlines pilots, declared to colleagues a week after trying the flight-control fix in a Boeing simulator in Miami in late September.

Bjorn Fehrm, an aerospace engineer and former fighter pilot in the Swedish Air Force, now a France-based aviation analyst with Leeham.net, has said Boeing’s original MCAS design was “criminally badly done … unforgivable,” and compared the system’s aggressiveness to a tiger. He too believes the redesign now makes the airplane as safe as the previous 737 model.

“There’s no part of any airplane out there that’s been as thoroughly vetted,” said Fehrm. “MCAS is no longer a tiger, but a house cat.”

The final pieces of that vetting are now imminent.

Boeing expects the Federal Aviation Administration (FAA) to formally unground the jet next month and to pin down all the pilot training requirements in January.

That’s pending a formal certification flight and a final evaluation of the software fix for the jet’s flight controls. And the FAA insisted Friday that it will take its time and won’t be swayed by pressure from Boeing.

After the FAA clears the plane to fly and issues the pilot training regimen, Boeing and the U.S. airlines will need 30 to 40 days to complete the enormous logistical challenge of getting their airplanes ready to fly after the better part of a year in storage.

Boeing will install the final software fix, refresh all the fluids and lubricants, do ground tests on the engines and flight controls, then conduct a checkout flight. The FAA will inspect every plane.

The worldwide fleet of MAXs previously delivered to airlines was 385, including 72 jets at U.S. airlines. With all the airplanes Boeing has built since, the total of parked MAXs is now just over 700.

American, Southwest and United have all already pushed out the MAX’s return to early March and have said it will rejoin their schedules in a phased approach over several months.

Boeing will also begin delivery of MAXs to carriers like Alaska, whose finished jets the manufacturer has parked and stored pending the ungrounding of the fleet.

Boeing’s fix
On the two crash flights, the pilots struggled to counter MCAS after it was triggered by a single sensor that fed the system an erroneously high value for the jet’s angle of attack — the angle between the wing and the oncoming air flow.

MCAS activated for up to 10 seconds, swiveling the horizontal tail, known as the stabilizer, so as to aggressively pitch the nose of each aircraft down. When countered by the pilots, the system stopped, then kicked in again with a new activation five seconds later. After a vain struggle against these repeated nose-down movements, each short flight — the first 12 minutes, the second just six minutes — ended in a high-speed nose-dive to earth.


Boeing’s fix for MCAS entails three changes to the system design:

*It will take input from the jet’s two angle of attack sensors instead of just one.
If they disagree by more than a nominal amount, the system assumes a false signal and will not activate.

If both angle of attack sensors somehow get stuck at the same wrong high value — perhaps if they got frozen in the wrong position — again MCAS won’t activate because the upgrade is designed to do so only when the angle moves suddenly from below the threshold to a new high value.

*If both sensors together register a sudden movement to a high angle of attack, the system will activate once only — not repeatedly, as in the accident flights.

*The capability of the system to move the horizontal stabilizer so as to pitch the jet nose-down will be limited. The pilot will always be able to counter it by pulling back on the control column.



In addition, Boeing has revised the overall architecture of the MAX’s flight-control computer system, so that on every flight the MAX takes separate inputs from the jet’s two flight-control computers, rather than just one as previously.

These two computers, each processing air data readings from the various sensors on both sides of the airplane, will cross-check and compare values. Again, if they disagree, automated systems including MCAS will be shutdown.

This change should catch any computer error as opposed to a sensor fault.

A person briefed on the details said such a shutdown would come in less than one-third of a second, so even if the pilots are distracted and fail to notice the airplane moving as it shouldn’t, the automation won’t be allowed to continue.

This addresses a problem identified in both accident investigations: that pilots took much longer to recognize and react to an MCAS fault than Boeing had assumed. By stopping any erroneous uncommanded movements automatically, the redesign takes the response out of the pilots’ hands altogether.

“We’re not letting the system run while the pilots are inattentive,” said the person, who required anonymity because parties to the ongoing accident investigations are not allowed to speak publicly.

Peter Lemme, a former Boeing flight-controls engineer and avionics expert who has been very critical of the original MCAS design, said Boeing has addressed all his concerns.

Once the FAA approves the fixes, said Lemme, he’ll fly on a MAX with “no misgivings.”

To get the flying public equally comfortable with the MAX, Boeing needs also to counter a recurring theme on social media: the idea that software shouldn’t have been needed in the first place and that the plane’s large engines throw its aerodynamic balance out of whack and make it “inherently unstable.”

Boeing says MCAS is needed not for stability but only to make the MAX feel the same to a pilot as the previous 737 model. The airplane will fly safely with or without MCAS, Boeing insists.

To prove that, Boeing has flown near-stall maneuvers in flight tests this summer with MCAS turned off. Safety regulators plan to do the same during upcoming recertification flights.

Pilot checklists and manuals
Pilots from American and Southwest, as well as Air Canada and some overseas carriers, in late September got hands-on experience with the new MAX flight controls in Boeing’s full-motion, full-flight simulator in Miami.

At a pilot-union conference a week later, Greg Bowen, training and standards committee chairman at the Southwest Airlines Pilots Association union, echoed APA’s DeLeeuw in declaring MCAS no longer a problem.

“In terms of handling characteristics … those anomalies have been designed out of the airplane,” said Bowen.

He said all that remains to be resolved is the training required for pilots, with new attention to how flight crews handle the confusion of a cockpit inundated with multiple alarms. The training and instructions need to be calibrated for pilots with lesser training and experience, he said.

The FAA will issue a report recommending the pilot training regimen, with a period for public comment likely in January. It’s expected that pilots already qualified to fly the older 737 model will be required to take only a two-hour computer course to highlight the differences on the MAX and the changes with the new software.

Bowen said the FAA is also considering significant changes to clarify the procedures in six pilot checklists that cover abnormal flight conditions, including the Runaway Stabilizer checklist that Boeing says the crews on both crash flights could have used to recover the airplanes.

Moving the tail manually
The Runaway Stabilizer checklist is a focus because the Ethiopian flight crew partially followed it: They cut off electric power to the horizontal tail, stopping MCAS from activating.
However, at that point the nose was still pitched downward and when they tried to move it back up manually by turning a wheel connected by cable to the stabilizer, they couldn’t budge it.

The problem was that as they coped with the emergency, the pilots allowed the plane to accelerate to 45 mph beyond the jet’s maximum design speed, causing high opposing forces on the tail that rendered the control surfaces immovable.

Even if the revised MCAS cannot act up again as it did on the crash flights, MAX pilots will still want to be comfortable with manual control of the stabilizer.

A 737 captain on a U.S. airline, who asked for anonymity to speak without permission from his employer, described his own extensive experience as a former test pilot of moving the tail manually.

He said that with the 737 tail at full nose-down position and at maximum design speed, it is “nigh impossible for a normal human to move the manual trim wheel in the nose up direction. The forces are too strong.”

Dennis Tajer, an American Airlines captain and APA spokesman, recently replicated that flight situation in a simulator, deliberately inducing an MCAS-style nose-down pitch at high speed, though still within the normal flight range.
He was able to move the wheel only “a couple of inches, but not enough.”

Tajer said that if the MAX is pitched down toward the ground, it gathers speed all too easily.

“The 737 is a slippery airplane,” said Tajer. “When you put the nose down, it wants to accelerate very quickly.”

He and his co-pilot in the simulator were able to recover control by using an old piloting skill called the roller-coaster technique that’s no longer in the manuals: letting go of the control column to ease the forces, then cranking the wheel, and repeatedly easing and cranking.

“Before we can be fully confident in the MCAS fixes we have to know more about the accompanying pilot training, emergency checklist changes, the extraordinary effort required to recover the aircraft with the manual trim wheel,” Tajer said.

While the FAA is likely to mandate hands-on Runaway Stabilizer training built into every airline pilot’s yearly recurrent training sessions in a simulator, some foreign regulators may make that a requirement for their pilots before they permit the MAX to return to service.

In a recent interview with trade magazine Aviation Week, Patrick Ky, executive director of the European Union Aviation Safety Agency (EASA), indicated that his agency will likely go along with the FAA in not making that a requirement.

Ky said that while some nations may demand simulator training for “purely political or public relations-driven” reasons, it would be “a complete disaster” if the FAA and EASA diverged. “We need to be fully harmonized,” he said.

That suggests the world’s two major aviation regulators are now aligned, though EASA’s schedule lags slightly the FAA’s. Ky said he expects an EASA decision on returning the MAX to the air “sometime in January.”

In the 737’s largest global market, China, the return of the MAX could be delayed by political factors around trade talks and U.S./China tensions.

For U.S. air travelers, though, the MAX could soon be airborne again.

Dominic Gates: 206-464-2963 or dgates@seattletimes.com; on Twitter: @dominicgates.
Seattle Times aerospace reporter