737 Max8. Safe or not safe?

[skotl]

That video has the usual "slight spin", which is all too common these days. Boeing almost certainly advertised that the max was "similar to fly" as the standard machine because it is. The problem of being nose light was fixed by software. The reason the planes crashed was nobody thought to tell the pilots that the software was controlling the takeoff angle, not some strange conspiracy by Boeing. How many plane orders would they have lost by telling airlines the pilots would need a few more hours to learn the aircraft before flying it? However the video, and the rest of the media are spinning a conspiracy about greedy capitalists. If they knew the reason for the first crash and did nothing about it, so allowing the second to happen, then yes Boeing are responsible for that, the usual corporate, "deny responsibility for everything" response is the cause of a lot of avoidable accidents, but the crash investigators would have known everything that Boeing knew about the first crash, and didn't do anything to prevent the second.

That's not how I read it. I don't personally believe that there was any conspiracy going on withing Boeing, nor do I believe that anyone consciously launched an aeroplane that they though was dangerous to fly.
My take is that if the information in the video is true (and that's a sizable "if") then could suggest that corners were cut for commercial expediency. It does seem to me, as a layman, that the change was sufficiently dramatic and far-reaching that a more extensive training programme could/should have been rolled out.

 

[ajlelectronics]

It does seem to me, as a layman, that the change was sufficiently dramatic and far-reaching that a more extensive training programme could/should have been rolled out.

I haven't watched any video clips but I have read up on it in the professional aviation press. I think that the aircraft evolved over many years, because regulations with certification meant that it was easier that way. Eventually, the quest for evolution went too far and the new engines could only be put outside CoG limits. The experience from the fighter jet that was also unable to fly showed that they could use software to keep it flying, although manual control was impossible. That also meant that they could sneak the "new" design out under the cover of previous certification. The sales folk at Boeing couldn't imagine that the software could give problems, being perfect so it wasn't considered important to inform anyone. After all, the pilot could just get on with his job in blissful ignorance. The software was clearly not good enough because whoever wrote the routine was not a pilot. Any pilot would have written it to hold the nose at maximum climb angle for the airspeed if the stick was fully back. The software treated excessive AoA as a stall which is daft in the extreme.

My personal feeling is that fly by wire is a step too far, let alone an aircraft that cannot be flown without computer control of basic functions like AoA.

 

[Munkul]

Avoiding speculation... regardless of what was to blame here....

surely engineering a commercial airliner to be inherently unstable in flight is the biggest no-no you could ever think of? You need a plane that at base level, CAN be flown?

Like it or not, we are in an age where weight, cost, competitiveness, fuel economy etc are all factors, and fly-by-wire systems are an inevitable outcome. The idea of Airbus's Flight Control Laws sounds like a really sensible approach to meet all needs... ie. you have "normal law" with speeds, pitch, AoA limits on autopilot, then differing levels of "law" giving the pilots more and more control right up to full manual control.
BUT as flight 447 shows, it's still not completely foolproof. (and reading about that accident - it sounds like the pilot in charge WAS an idiot, and directly caused the crash due to incompetency - with no idea how the systems worked)

We can't go backwards on automated flight control systems. We would end up with more crashes due to idiots, like the pilot of flight 587 who shook the rudder controls so hard that it fell off. And that was an 80's plane with no fly-by-wire...

It sounds very like the new AoA software was incorrectly designed and they simply didn't realise what effect it would have on the way the pilots usually operate and understand the control modes.

 

[KemppiFrog]

Elsewhere, a 737 pilot was pointing out that the guys in the second accident were ignoring basic airmanship checks. The system was giving unstable airspeed and stall warnings, yet was speeding up. Also they pulled the flaps up. If you raise the flaps with low speed, you risk a stall. While the flaps are deployed, the MCAS is disabled. The bust AOA sensor on the port side was scrambling the information to the Captain. With such erronious readings, they should have used the right hand display, which was giving more stable info. The normal checks for their situation, they just did not follow.

 

[cardiffrob]

737... LandRover?

Back in 1948 the Landie was state-of-the-art and probably quite safe. By 2000 it was heavier, had a bigger engine, a longer wheelbase, fatter tyres, bigger brakes, electric windows etc but was still a Landie. By 2016 they realised they had milked that baby for a long enough time and decided to bin it. By then it was nowhere near getting any sort of Euro NCAP rating.

The 737-200 was flying when I was born. It was a 100 seater designed for 2 hour city-hops. Now it flies 200 people over entire continents and oceans. It has become a Frankensteins' Monster with an engine so big it can't fit under the wings or even in front like the 737-800. It hangs so far forwards that it needs MCAS to even be approved under the Grandfather rights due to the poor stability at low speed/High alpha. Time to kill it, quietly, round the back of the Barn. One good bullet to the head.

On day one of my 757-to-737 course the instructor said "Welcome to the 737....this B***ard is gonna try and kill you every chance it gets" Still fancy buying a holiday with TUI and putting yer kids on a 73Max?

Rob. 10,000 hours, 1500 on the hated 737-800 and Max
PS I'd happily drive a Landie, though.

 

[daedalusminos]

Something obviously went seriously wrong during the design stage. DFMEA (Design Failure Mode Effects and Analysis) is a cross industry standard to minimise anything like this happening. Essentially you hypothesise scenario, evaluate the outcome then design to minimise the risk. This should be detailed down to broken wires, loose bolts etc. Suppliers flow their analysis up the design chain so that upper tier customers can negate risks.

 

[KemppiFrog]

As I understand it, the bigger engines needed to be fitted a bit further forward and slightly higher, as they were always close to the ground. Not out of COG, but at certain thrust levels, they caused the plane to pitch up more than would be expected from the control loads. So the software mod, was to tell the trim to go to nose down in small increments to off set the effect. Unfortunately they didn't think it was important enough to tell the pilots as part of a training program, or, to look into what might happen if it was fed bad data from a failed sensor. If the pilots had treated it as a trim runaway from the start, likely they could have sorted things out. But it seem they didn't recognise what was going on. Lots of warnings and confusing info causing sensory overload and bad decisions. They did try to re-trim in small amounts late on, but not enough to make any difference. If they had reconnected the electric trim and sat on the button until it got to somewhere near neutral, THEN pulled the trim breaker which would have stopped MCAS pitching it down again. Easy now to look at it, rather than being in the seat with lots of alarms and stick shakers going on. But it appears they did not follow the book.

Good to have you in this Rob. Any comments on why, with over 300 a/c delivered this has occured on two flights in uurm, other countries. The first was after a duff sensor had been 'Fixed' The second is being blamed on a bird strike?? (As trhe primary cause)

 

[cardiffrob]

If it starts to trim and you start to trim in the opposite direction it just stops. When you then release, MCAS can wind the trim back again. You THOUGHT you were undoing the trim and then it didn't do anything until you stopped trying, when it went the other worse all by itself, in small blips every 15-20 seconds or so. So weird that your brain struggles to compute to identify what is going wrong. Imagine if your car suddenly decided that any left turn on the steering wheel would turn the wheels the other way....at 400 mph. Flustered and confused? You betcha!
There is a concern that with the Pilots pulling back on the stick and the MCAS pushing forwards, the tension on the screwjack (think lathe feedscrew) was so stiff that the manual trim (think big handwheel) couldn't be turned to bring the trim back. The only way to unload the tension would be to let go and watch it dive as you tried to wind the trim wheel back. No way at 1000 feet and 400 mph. I don't think the nationality has too much to do with this. Have a look at " https://assets.publishing.service.g...-_AAR_3-2009_Boeing_737-3Q8__G-THOF_06-09.pdf " to see how Brits screw it up, too. The whole Kegworth disaster happened after 2 guys got confused following a brief 737-300 to 737-400 conversion course lasting a half day (ring any bells???) where the failed to understand the complex changes. There's very little new in aviation.

136 of these 737s have been destroyed in service. Not a great number but still too bloody many and I hated every minute of my time on that fleet. "The illegitimate child resulting from an engineer being gang-banged by accountants", so they say.

Flying in a 737 Max is on the same level as using cheap, discount Chinese 9" cutting discs in an unguarded grinder. Why would you take the risk?

 

[skotl]

If it starts to trim and you start to trim in the opposite direction it just stops. When you then release, MCAS can wind the trim back again. You THOUGHT you were undoing the trim and then it didn't do anything until you stopped trying, when it went the other worse all by itself, in small blips every 15-20 seconds or so. So weird that your brain struggles to compute to identify what is going wrong. Imagine if your car suddenly decided that any left turn on the steering wheel would turn the wheels the other way....at 400 mph. Flustered and confused? You betcha!
There is a concern that with the Pilots pulling back on the stick and the MCAS pushing forwards, the tension on the screwjack (think lathe feedscrew) was so stiff that the manual trim (think big handwheel) couldn't be turned to bring the trim back. The only way to unload the tension would be to let go and watch it dive as you tried to wind the trim wheel back. No way at 1000 feet and 400 mph. I don't think the nationality has too much to do with this. Have a look at " https://assets.publishing.service.g...-_AAR_3-2009_Boeing_737-3Q8__G-THOF_06-09.pdf " to see how Brits screw it up, too. The whole Kegworth disaster happened after 2 guys got confused following a brief 737-300 to 737-400 conversion course lasting a half day (ring any bells???) where the failed to understand the complex changes. There's very little new in aviation.

136 of these 737s have been destroyed in service. Not a great number but still too bloody many and I hated every minute of my time on that fleet. "The illegitimate child resulting from an engineer being gang-banged by accountants", so they say.

Flying in a 737 Max is on the same level as using cheap, discount Chinese 9" cutting discs in an unguarded grinder. Why would you take the risk?

Given that the plane is now grounded worldwide, do you think that there's any way back for the 737-8, Rob? It seems like compounding software fix on software fix to overcome inherent physical & aerodynamic instability is a hiding-to-nothing. Might Boeing or the various aviation administrations permanently ground the plane?

 

[Munkul]

Flying in a 737 Max is on the same level as using cheap, discount Chinese 9" cutting discs in an unguarded grinder. Why would you take the risk?

interesting to have your first hand experience/opinion on this, Rob. Is this the common opinion amongst pilots, that they all hate flying 737's?

 

[ajlelectronics]

interesting to have your first hand experience/opinion on this, Rob. Is this the common opinion amongst pilots, that they all hate flying 737's?

The aviation press gives that impression.

 

[jimbo84]

Might be over simplifying or maybe there already is but I feel like there needs to be a button that in situations like this the pilots can hit and the computers have no influence over the plane other than making the control surfaces do what the pilot tells them to.

There seems to be a battle between man and computer.

 

[KemppiFrog]

Might be over simplifying or maybe there already is but I feel like there needs to be a button that in situations like this the pilots can hit and the computers have no influence over the plane other than making the control surfaces do what the pilot tells them to.

There seems to be a battle between man and computer.

The problem might be that the pilot normally relies on the computor info to fly the plane. So reverting to stick and rudder skils (if they had them)there is little info to rely on. The little Piper I flew had airspeed, engine revs and temp guages. One didn't pay much attention to them, jusb did it by feel. I also did a microlight course. The bloke said, do it by feel, not the stuff on the instruments.
Whole different world to big planes, where numbers matter. If the numbers are corrupted, the pilot has few references.

 

[cardiffrob]

737 flies like a LWB Landie corners at speed.

Lots of people have never flown anything else but ask a 747/757/767 pilot which they'd prefer and they'll never go for a 737, even the earlier versions. Too many add-ons designed to make money.

737 overhead panel. Compare this to the Embraer panel for a similar sized but far more modern twin-jet. Ergonomic???

I think the 737-800 will continue to be a good financial success but the Max will die quietly. In 12 months I'd expect Boeing to announce a 737 replacement partly built in Asia, presumably in the factory next to the one making TIG welders and drill bits that we see on here.

 

[tlovatt]

Might be over simplifying or maybe there already is but I feel like there needs to be a button that in situations like this the pilots can hit and the computers have no influence over the plane other than making the control surfaces do what the pilot tells them to.

I believe it has been reported, there were a couple of switches the pilots could have used to turn the system off, but as with all of these things, the pilots need to identify what is happening, the solution and then to have time to recover the situation, the lower the altitude the less time they will have.

Also do not forget the big advantages computers can have, just look at the landing on the Hudson, a skilled experienced pilot aided and assisted by computer controls that undertook quite a bit of work for the pilot in keeping the plane stable and in the air so the pilot can concentrate on other things such as where to land, avoiding boats etc.

 

[Tinbasherdan]

I believe it has been reported, there were a couple of switches the pilots could have used to turn the system off, but as with all of these things, the pilots need to identify what is happening, the solution and then to have time to recover the situation, the lower the altitude the less time they will have.

Also do not forget the big advantages computers can have, just look at the landing on the Hudson, a skilled experienced pilot aided and assisted by computer controls that undertook quite a bit of work for the pilot in keeping the plane stable and in the air so the pilot can concentrate on other things such as where to land, avoiding boats etc.

I believe sully had a gripe that the airbus kept trying to drop the nose when he was flaring for the landing

 

[mart]

American Airlines pilots confronted Boeing about potential safety issues in its 737 Max planes in a meeting last November, US media are reporting. They urged swift action after the first deadly 737 Max crash off Indonesia in October, according to audio obtained by CBS and the New York Times. Boeing reportedly resisted their calls but promised a software fix. But this had not been rolled out when an Ethiopian Airlines' 737 Max crashed four months later, killing 157 people.
https://www.bbc.co.uk/news/business-48281282

 

[cardiffrob]

The 737 has big cables from the controls to the surfaces. If you switch off ALL the hydraulics (called manual reversion) you fly it with staggeringly heavy controls but it is possible to fly like that, and we do that in the Sim every few years. The stab trim that MCAS wound fully forwards can be disconnected by 2 small switches below the throttles. It is thus entirely possible to fly it like a great big Cessna 2-seater with no computer input or hydraulic input. Even the stab trim can be manually wound round using the big wheel, assuming it isn't stuck tight by aerodynamic forces. One of the only Jets that can be flown like this.

Switch it all off...it still flies. Rely on it when it goes wrong and you run the risk of something nasty. Incidentally, the Ethiopians seem to have correctly disconnected the power to the Stab Trim but then stuck it back on.

 

[cardiffrob]

Just to add to the fun...

Top 2 switches turn on the engine Anti-Icing (like a choke) for flying in icing conditions and the 2 identical switches just below it switch off the hydraulics to the controls. Guess what OFTEN happens when tired pilots in dark cockpits go to turn on the Anti-Ice? Oh yeah, DOWN is ON and UP is OFF. What a POS aeroplane design.

 

[RWD3M]

737 flies like a LWB Landie corners at speed.