What really brought down the Boeing 737 Max?

[GL]

What is wrong with this statement -
"The reason the 2 Maxes crashed is because the pilots did not have the insight or experience to recognise a trim runaway and deal with it fast enough."

Because the problem did not manifest itself as trim runaway.

When all the noise about MCAS etc is cut away - I think a blindingly obvious trim runaway was the whole problem. That's why the pilots should have been trained to switch off the two Stab trim switches - pronto. But pilots get complacent in their trust of modern airline engineering and software, and when things go awry - the first question they ask is the classic Airbus question - "what's it doing now?" - rather than just fly the damn plane.
When the max crews had an uncommanded nose down trim change they should have known to switch the trim tab cutouts off. Basic PPL stuff - hit the trim cutoff and fly the plane. IINM its a certification requirement of any electric trim system that a trim cutoff switch has to be easily on hand.

[Antman]

Basic PPL stuff

You rated on a B737 GL? its hardly a basic aircraft!

By the way, MCAS trims then stops, then trims, then stops etc
A trim runaway just continues trimming!
These guys had been trained on a -800 which has a speed trim system,
which also trims and stops and trims and stops.
Therefore this may be identified as the speed trim system, both these crashes where caused
By faulty angle of attack sensors (SINGLE SOURCE????)

If this was “basic PPL stuff” then why is this aircraft still grounded with no end in sight?

Got to love when people make statements about stuff they no nothing about, particularly journo!

[nic weskus]

Guys.
I am not a pilot.
So on this forum is not my place to try to be clever.

I know somone who is a consultant for MOD.
He was also contacted by the powers-that-be from Boeing.
He sent his thoughts to me about this issue via Whatsapp.
You all know him.
His Avcom name is Blender.
Maybe he can explain more.

Les had been online with them many late nights.
Maybe he can share.

I do know that there are many more issues involved.
Please follow his train of thoughts.

And he calls a spade a spade.

Thanks
Nic
Neither will he do no personal attacks

[MadMacs]

What is wrong with this statement -
"The reason the 2 Maxes crashed is because the pilots did not have the insight or experience to recognise a trim runaway and deal with it fast enough."

I doubt that any airline would let a pilot loose on the flight deck without having passed all the sim checks which would include a runaway stab. I can't remember the interim crash report and do not have it to hand but the pilots did kill the stab trim via the switches, iirc.

[Volo]

Basic PPL stuff

You rated on a B737 GL? its hardly a basic aircraft!

By the way, MCAS trims then stops, then trims, then stops etc
A trim runaway just continues trimming!
These guys had been trained on a -800 which has a speed trim system,
which also trims and stops and trims and stops.
Therefore this may be identified as the speed trim system, both these crashes where caused
By faulty angle of attack sensors (SINGLE SOURCE????)

If this was “basic PPL stuff” then why is this aircraft still grounded with no end in sight?

Got to love when people make statements about stuff they no nothing about, particularly journo!

......................................................

A bit rough on Gl there Antman - I think most people who have read most of the posts in this thread know as much as Boeing and the FAA about the whole saga . The average reader probably knows more than the unfortunate pilots of both those ill-fated Max 8 s .
I have understood all through this debate that it was and is a 100% avoidable accident if certain procedures are followed timeously even with the existing software . I believe this was demonstrated when other Max8s suffered attack sensor failures.
Clearly this does not satisfy either Boeing or the FAA hence the ongoing revision of the software .
I also read somewhere that that there is more to the whole saga because of the reliance of Boeing on an inadequate computer back-up which may be why there is a delay in the fix - but that's only a guess ???

[Orthin Opter]

What is wrong with this statement -
"The reason the 2 Maxes crashed is because the pilots did not have the insight or experience to recognise a trim runaway and deal with it fast enough."

I doubt that any airline would let a pilot loose on the flight deck without having passed all the sim checks which would include a runaway stab. I can't remember the interim crash report and do not have it to hand but the pilots did kill the stab trim via the switches, iirc.

It would seem that in the case of the second aircraft, the stab trim was switched off, but for whatever reason, the pilots did not wind the stab manually till the aircraft was in trim again. For whatever reason, they chose to trust the aircraft to fix the problem and put the switches back on again. Game over. Another problem is that there is only one speed for stab trim and that is high speed for large trim changes with flap extension. During cruise a slow trim is required, but apparently not fitted to the Max. MM, can you confirm?

[nic weskus]

Agreed.
He should have flown the aerie by hand.
Like old-school the way you guys were trained when you first flew.
Unluckily all of the systems overrode him.

As you had rightly said:"game over"

[kennyhubbard]

Volo,

Actually Antman is correct. Harsh but spot on. When people start suggesting that 6000 hours + pilots did not do what a basic ppl would have done then I say a certain amount of rational thought has left the building.

From what I have read this was potentially avoidable but not 100%. Think back to the movie about Sully. They ran dozens of simulations to eventually produce a result that said he could have made a runway. No doubt boeing would love to show that the crew were too slow to identify the problem and that allowed them to get into un unrecoverable aircraft state.......just like they tried to do to Sully. The documented procedure for the position they were in did not work, so lets just shoot holes in what they did do.

[nic weskus]

Never implied.

They obviously did their best.

When the powers-that-be were selling Boeings their test-pilot did a barrel roll. In the 707.

Not supposed to be done by any means.
Not according to the books anyway.

When he landed his boss was all over him.
He answered:
"But you told me to sell aeroplanes"

The times before computers took over.
When you could still walk into the cockpit and have a coffee with the Captain.

[nic weskus]

Basic PPL stuff

You rated on a B737 GL? its hardly a basic aircraft!

By the way, MCAS trims then stops, then trims, then stops etc
A trim runaway just continues trimming!
These guys had been trained on a -800 which has a speed trim system,
which also trims and stops and trims and stops.
Therefore this may be identified as the speed trim system, both these crashes where caused
By faulty angle of attack sensors (SINGLE SOURCE????)

If this was “basic PPL stuff” then why is this aircraft still grounded with no end in sight?

Got to love when people make statements about stuff they no nothing about, particularly journo!

Antman - don't shoot the messenger!
Two points - I phrased the initial statement as a hypothesis - as a 'straw man' to be shot down. Attack the hypothesis - not me! (play the ball - not the man!)
The second point is that I was not presuming to know how to fly a 737-800 or Max - but to point out that even PPLs in a pappa charlie know how to deal with a trim runaway - where to find and pull the breaker - or switch the A/P off.
One of the key attacks on my hypothesis is as, someone has pointed out, the MCAS system only goes to sleep when over ridden and then 30 seconds later wakes up again and keeps pushing the nose down. And when the Ethiopian crew could not overpower the stab trim by pulling back on the column or turning the trim wheel crank, they did the smart thing and turned the trim tab power back on and tried to use the normal electric trim switches to trim the nose up.
But the 'kanniedood' demon in the MCAS beat them.

[nic weskus]

Guy.
My reply to you is in reading my previous post.
And your comment was spot-on according to what I had tried to figure out.

You one of the legends.

[Chalkie]

Double transmission. I was typing slowly, others were quicker...

If this was “basic PPL stuff” then why is this aircraft still grounded with no end in sight?

In defence of GL. Basic PPL stuff means you fly your aircraft and keep it in trim, the pilots apparently did not do this but relied on automation. Perhaps that is the modern complacency trap? I have trained enough people on the B737 and although it is a complex aircraft, my briefing was always: Fly it like you fly a Baron.

The reason the aircraft is still grounded is huge and political. Boeing beancounters ruled the company not the engineers as previously was the case. The FAA gave Boeing the right to oversee themselves, so Boeing fiddled the system. They said it was the same as the old system, only better; then so as not to have the FAA scratch around, they tied the system to one AoA probe, because to add another would indicate, perhaps, a need for redundancy and would open the door for the FAA to step in and insist on a recertification program.

Blaming the pilots is the easy way out as they are not here to defend themselves. If they were, they would tell the court that Mr Boeing did not mention the system at all, in ANY of their manuals. So when the system malfunctioned and it was not like the 'normal' runaway trim, the pilots were confused. I can understand that.

Imagine you are the first pilot: stab trim runs 3 seconds than stops. ?? WTF was that? Stab trim runs 3 seconds... How long did they have to realise something VERY strange was going on? Something they were not trained for? A stab runaway does NOT stop, till you stop it...

Soon the autopilot would trip off due to massive out of trim forces on the elevator and the aircraft was pointing nose down, then in the dire position they were in, they are (now) expected to have disabled the stab trim and wound in nose up trim. Meanwhile the MCAS system is doing its job, trim nose down wait a bit then trim nose down, etc... Was there time for that whilst they were both pulling nose up as hard as they could? Did Boeing think of setting any limits to the authority of this system, or not?

Hopefully the problem will be corrected, the manuals updated and the B737 will return to being the great aircraft it always was.

[GL]

Thanks for the support Chalkie
Just one thing - I reckon this para of your pretty much sums up the pilots problem - but the A/P did not trip off because it was not on - i understand the MCAS was only operational with the A/P off - and the flaps up?

Soon the autopilot would trip off due to massive out of trim forces on the elevator and the aircraft was pointing nose down, then in the dire position they were in, they are (now) expected to have disabled the stab trim and wound in nose up trim. Meanwhile the MCAS system is doing its job, trim nose down wait a bit then trim nose down, etc... Was there time for that whilst they were both pulling nose up as hard as they could? Did Boeing think of setting any limits to the authority of this system, or not?

[Airwayfreak]

I think a blindingly obvious trim runaway was the whole problem.

Sorry GL but you are wrong. This was not a runaway trim issue and did not present itself as such. It was not blindingly obvious as runaway trim is.

Had the pilots at least been warned about MCAS they might have included this in their initial fault diagnosis, but since they were not aware of the existence of MCAS, they were trying to isolate the fault elsewhere

PS: Just saw Chalkie's response. What he said.

[ACE MAN]

Basic PPL stuff - yea , I do not think so.

On a quick note the largest operator of the MAX is/was Southwest. Minimum requirements to join Southwest as an FO!,
“Flight Experience
We require 2,500 hours total flight time or 1,500 hours total flight time in a turbine aircraft.
Additionally, we prefer a minimum of 1,000 hours in a turbine aircraft as the Pilot in Command. Only time in a fixed wing aircraft is counted. This specifically excludes simulator, helicopter, WSO, RIO, FE, NAV, EWO and UAV.
Actively flying two of the past five years is preferred.”

FAA require regular public transport airline pilots to have at least an ALTP and 1500hrs AFAIK. There has to be some merit in this.