Air Crash Thread: Boeing MAX and Other Problems

[Imari]

Since commercial aviation got off the ground in the 1930's(?), many, many carriers have gone out of business. National (state sponsored) airlines may operate at a loss, simply for the prestige, tourism and other benefits that air travel brings.

Since [insert industry here] began, many businesses in the field have ceased operating.

That's just a fact of business. Some fail. That doesn't mean that the industry as a whole operates at a loss.

 

[GTV0819]

Since commercial aviation got off the ground in the 1930's(?), many, many carriers have gone out of business. National (state sponsored) airlines may operate at a loss, simply for the prestige, tourism and other benefits that air travel brings.

As you said this, one particular airline from the past suddenly came into my mind; Pan-American. Though it is nothing significant of this thread.

 

[Swagger897]

Or Eastern...

 

[daan]

The French authorities managed to miraculously avoid the blame for rushing Concorde to the runway due to the queuing Presidential flight.

As I understand it, Concorde was always rushed to the runway due to its engines being very inefficient for taxiing. If it taxiied for too long it would have been short on fuel for the Atlantic crossing so it was always cleared to go as soon as it started up.

 

[Dotini]

Or Eastern...

Long lists of airline bankruptcies in the US alone.
https://en.wikipedia.org/wiki/List_of_airline_bankruptcies_in_the_United_States

 

[Barra333]

This episode of The Daily is worth a listen. There is also a transcript on that page if you prefer.

 

[GTV0819]

Ouch.

 

[TenEightyOne]

Ouch.

Yes, everything the Express writes is like that.

 

[GTV0819]

What other flaw exactly? I wonder

 

[Dotini]

What other flaw exactly? I wonder

That story is correct. It is confirmed by expert reporting from the Seattle Times. Even so, it is just barely conceivable that all necessary steps can be accomplished to meet an October certification for return to service. Otherwise, 10,000 Boeing employees get laid off. Really, Seattle could do with a substantial downsizing, and this could be a good start.

 

[TenEightyOne]

That story is correct. It is confirmed by expert reporting from the Seattle Times. Even so, it is just barely conceivable that all necessary steps can be accomplished to meet an October certification for return to service. Otherwise, 10,000 Boeing employees get laid off. Really, Seattle could do with a substantial downsizing, and this could be a good start.

I'm a bit confused - I thought all Boeings took information from the secondary (co-pilot) FCM when the override command was given? Or is this something that was removed from MAX as part of the new system redundancy model?

How's your pension, down to beans on toast yet? (I jest!)

 

[Dotini]

I'm a bit confused - I thought all Boeings took information from the secondary (co-pilot) FCM when the override command was given? Or is this something that was removed from MAX as part of the new system redundancy model?

How's your pension, down to beans on toast yet? (I jest!)

Ha-ha. Now here are the facts;
https://www.seattletimes.com/busine...software-redesign-of-737-max-flight-controls/
My pension is doing just fine, thank-you. But it is just a small fraction of my revenue.

 

[TenEightyOne]

here are the facts;
https://www.seattletimes.com/busine...software-redesign-of-737-max-flight-controls/

Thank you, certainly a more informative read than Sputnik offered.

Given the particular discussion that's run throughout this thread about whether some pilots are more able/equipped to recover an aircraft suffering this particular problem it was interesting to read the following:

It has specifically rejected Boeing’s assumption that the plane’s pilots can be relied upon as the backstop safeguard in scenarios such as the uncommanded movement of the horizontal tail involved in both the Indonesian and Ethiopian crashes. That notion was ruled out by FAA pilots in June when, during testing of the effect of a glitch in the computer hardware, one out of three pilots in a simulation failed to save the aircraft.

That suggests that even a pilot who knows the system, who knows what to expect and who is (presumably) considered extremely well-trained has a 66% chance of recovery during a trim runaway of the kind that's presumed to have occurred in the two MAX crashes. That's pretty sobering. There must be a lot of pilots thinking about their own flights right now, we know from the NASA documents that several had to restrict runaway trims during MAX's original service period.

 

[GTV0819]

That story is correct. It is confirmed by expert reporting from the Seattle Times. Even so, it is just barely conceivable that all necessary steps can be accomplished to meet an October certification for return to service. Otherwise, 10,000 Boeing employees get laid off. Really, Seattle could do with a substantial downsizing, and this could be a good start.

So Boeing's soap opera continues.

 

[GTV0819]

So what does this actually mean, hmm...

 

[TenEightyOne]

So what does this actually mean, hmm...

I think it means what the story says. You can book advance flights through airlines. Airlines are expecting MAX to be back in service in the future. Some of those future flights are expected to be on MAX aircraft.

If MAX isn't flying then those flights won't be on MAX aircraft. Seemples.

 

[GTV0819]

So there's a possibility that other airlines which have the same aircraft in their fleet would also offer future flights involving the suspended aircraft, which they could offer tickets in discounts as well.

However, there's still no guarantee that they might be back in service before this year ends.

 

[TenEightyOne]

So there's a possibility that other airlines which have the same aircraft in their fleet would also offer future flights involving the suspended aircraft, which they could offer tickets in discounts as well.

Yes. Why wouldn't they? Any discounting is up to them of course but it isn't unusual for tickets bought in advance to be discounted and for the price to rise as the flight sells out.

However, there's still no guarantee that they might be back in service before this year ends.

That's correct. And airlines are suffering.

 

[Barra333]

So there's a possibility that other airlines which have the same aircraft in their fleet would also offer future flights involving the suspended aircraft, which they could offer tickets in discounts as well.

However, there's still no guarantee that they might be back in service before this year ends.

Remember, passengers buy a ticket for a given route not a ride on a specific aircraft. Under normal circumstances, the plane type is fairly predictable, but in this case, it is more of a placeholder probably in order to get some kind of seat plan on the system.

 

[GTV0819]

I know and that these trips set for the future will still push through regardless if the 737 MAX planes didn't operate back in time for all the pending flights. They will obviously use their other planes to go on.

 

[TenEightyOne]

I know and that these trips set for the future will still push through regardless if the 737 MAX planes didn't operate back in time for all the pending flights. They will obviously use their other planes to go on.

So no news then?

 

[GTV0819]

So no news then?

What on earth do you mean by that?

 

[TenEightyOne]

What on earth do you mean by that?

So what does this actually mean, hmm...

I mean it means nothing. Airlines are planning for when they get to fly their MAX aircraft again, and why wouldn't they?

 

[GTV0819]

Airlines are planning for when they get to fly their MAX aircraft again, and why wouldn't they?

Certainly, but like what's already been suggested earlier, it remains to be seen whether the aircraft will be back in service for the remaining months to come or not.

 

[TenEightyOne]

Pilots "did not react the way Boeing expected", according to the NTSB. This is raising questions about how pre-certification testing is conducted - it seems clear that professional company test pilots would go into a simulator with more knowledge of the systems than a "regular" pilot would. BBC.

 

[Barra333]

But the system re-starts if the false readings continue, creating a tug of war between the aircraft and its crew

This seems to be a fundamental problem to me:

Plane: The sensor said your angle of flight is too high, I'm just gunna push the nose down a bit
Pilots: No, its good. The sensor must be wrong. <Pulls up>
Plane: The sensor said your angle of flight is too high, I'm just gunna push the nose down a bit
Pilots: No, its good. The sensor must be wrong. <Pulls up> <Turns MCAS off>.
Plane: Just turning MCAS back on. The sensor said your angle of flight is too high, I'm just gunna push the nose down a bit.
.
.
.
.
Crash.

 

[TenEightyOne]

This seems to be a fundamental problem to me

Just as it does to everyone of sound mind... except Boeing and the FAA about 18 months ago. The problem can be mitigated with the addition of extra sensors and an extra cockpit readout but, inexplicably, these were part of a paid "extras" package which Boeing played down the importance of to customers.

 

[Danoff]

Just as it does to everyone of sound mind... except Boeing and the FAA about 18 months ago. The problem can be mitigated with the addition of extra sensors and an extra cockpit readout but, inexplicably, these were part of a paid "extras" package which Boeing played down the importance of to customers.

Were there sensors which were available to be had? I was under the impression that a redundant sensor was simply not on the table. The read-out was one that some airlines didn't want.

I still think there's another problem here, which is that the hydraulic actuation of the trim is not available once the automatic system is disabled. The manual adjustment requires unloading the yoke, which isn't an available option at some altitudes, so hydraulic assistance (or more leverage for the mechanical system) is needed. I think we discussed that the hydraulic assistance with the MCAS off was even available in earlier designs.

 

[TenEightyOne]

Were there sensors which were available to be had? I was under the impression that a redundant sensor was simply not on the table. The read-out was one that some airlines didn't want.

Yes, the sensor is available as part of the same extra option which adds the AoA disagree alert - in fact there's no point having the alert without the extra sensor, as I understand it. It's evident now that the extra sensor was very likely to have been safety-critical. It was not sold as such and, many are arguing, should never have been sold as an optional extra at all. Many airlines buy "vanilla" aircraft and expect them to be fully, safely functional. Big airlines (like Ethiopian Air with over 100 Boeings) wouldn't have seen the need to add $100,000 per plane to their 20-plane MAX order as it wasn't a safety-critical addition.

I still think there's another problem here, which is that the hydraulic actuation of the trim is not available once the automatic system is disabled. The manual adjustment requires unloading the yoke, which isn't an available option at some altitudes, so hydraulic assistance (or more leverage for the mechanical system) is needed. I think we discussed that the hydraulic assistance with the MCAS off was even available in earlier designs.

It's only a problem in the MAX, that's because the angle of automated alteration at the tail is so hugely significant. Aircraft don't get into that state under other conditions - if they did then we'd see lots of runaway trim crashes that the pilots couldn't recover, but we don't. The pilot can use the thumb switches to alter trim when MCAS isn't working, the problems on MAX are that a) MCAS reactivates and overrides those trim controls and b) The angle of deflection of the taileron is so great that it even taxes the electrical controls. Air Force pilots on 707s used to practice a special manouver to "unload" the tailerons but that hasn't been a requirement on any military or civilian aircraft in the modern (40 year-ish) era.

 

[Danoff]

Yes, the sensor is available as part of the same extra option which adds the AoA disagree alert

That's a confusing article. This suggests that the 2 sensors are standard, but that the MCAS only listens to one.

Regardless, Ethiopia turned off the MCAS and still couldn't save the plane. The indicator lights would not have saved them, they knew what the problem was.

The pilot can use the thumb switches to alter trim when MCAS isn't working, the problems on MAX are that a) MCAS reactivates and overrides those trim controls and b) The angle of deflection of the taileron is so great that it even taxes the electrical controls. Air Force pilots on 707s used to practice a special manouver to "unload" the tailerons but that hasn't been a requirement on any military or civilian aircraft in the modern (40 year-ish) era.

This was what happened to EA, they couldn't release the yoke, but they also couldn't crank hard enough on the trim. The thumb tabs weren't available with MCAS off, and with MCAS on it was overridden.