Ethiopian Airlines B737 crashes

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Orbit v2

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Here's the article that image came from. It does also make the point that it's the engine nacelles that generate unexpected lift (and pitch up) at high AOA. I guess that is new, whereas before it was well understood how engine thrust does it. Still though, I would see this as something that pilots can be trained to handle.

 


silverharp

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it wasnt really a software problem, it was developing new planes by modifying old designs on the cheap
 

Pabilito

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What is the difference between the design envelope and the flight envelope?
The Design envelope constrains the parameters designers are permitted to play with in order to design a safe aircraft whereas the Flight envelope defines the safe flying limitations of a specific aircraft design.
 

Pabilito

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Here's the article that image came from. It does also make the point that it's the engine nacelles that generate unexpected lift (and pitch up) at high AOA. I guess that is new, whereas before it was well understood how engine thrust does it. Still though, I would see this as something that pilots can be trained to handle.

Unexpected Lift..? "Unexpected" by who? ..

The designers designed an aircraft so there should not be any unexpected results.. otherwise they are incompetent aircraft desigeners.
 
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bormotello

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Why handling of failed of MCAS was not part of Boeing 737 MAX pilots?
- Sources with knowledge of the doomed Lion Air cockpit voice recorder revealed how pilots scoured a manual in a losing battle to figure out why they were hurtling down to sea.
- Communications showed that in the final moments, the Lion Air captain tried in vain to find the right procedure in the handbook, while the first officer was unable to control the plane.
 

Orbit v2

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Unexpected Lift..? "Unexpected" by who? ..

The designers designed an aircraft so there should not be any unexpected results.. otherwise they are incompetent aircraft desigeners.
Again, I refer you to my reply in post #61.
 

Orbit v2

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The Design envelope constrains the parameters designers are permitted to play with in order to design a safe aircraft whereas the Flight envelope defines the safe flying limitations of a specific aircraft design.
So you think the constraints on the design of a safe aircraft aren't the same as the safe flying limitations of a specific aircraft design? How can you have a safe aircraft that isn't safe to fly?
 

cozzy121

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Too little ...


  • Boeing confirms changes to training and operation of its 737 Max airplane.
  • 346 people have died after two separate crashes involving the 737 Max.
  • The Federal Bureau of Investigation is now investigating the plane's certification process.
Hopefully with the Feds involved some light will be shone on the links between the FAA and Boeing as they rushed to compete against the Airbus A320 Neo
 

silverharp

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I don't think I will fly with an airline that has them
 

Pabilito

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So you think the constraints on the design of a safe aircraft aren't the same as the safe flying limitations of a specific aircraft design? How can you have a safe aircraft that isn't safe to fly?

I didn’t say any of that. The simple point I was making and one that you don’t seem to be able to grasp is that the design envelope is the rules and regulations that govern aircraft design just like building regulations govern building design. Following the exact same regulations i.e. operating with the design envelope will produce any number of very different aircraft with very different performance characteristics. For example, a regulation might say the maximum wing span is 80m therefore an aircraft who’s wing span is less than 80m is within that parameter of the design envelope.

In this case Boeing appear to have used the existing type certification of the 737wings but added an engine to that wing design that seriously compromises the overall wings performance in relation to lift.

I would therefore argue that the MAX wing and engine modules are not compatible and most likely wouldn’t have been certified had they both been subject to the far more rigorous process involved in certifying a brand new ‘type’ aircraft.
 

Pabilito

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I don't think I will fly with an airline that has them
A lot of people are thinking that way.

The MAX is analogous to a car that’s prone to dangerously lurching towards the opposite side of the road so the manufacturers have put in a software kludge that nudges the steering wheel to pull it back… plus they didn’t tell anybody about this because … yes because nobody would knowingly buy or travel in such a car.
 

silverharp

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A lot of people are thinking that way.

The MAX is analogous to a car that’s prone to dangerously lurching towards the opposite side of the road so the manufacturers have put in a software kludge that nudges the steering wheel to pull it back… plus they didn’t tell anybody about this because … yes because nobody would knowingly buy or travel in such a car.
its a serious confidence killer for sure, I can see why they wouldn't. I understand military jets need computer assist these days because the designs are inherently unstable but I want my passenger jets to be stable.
Given that the FAA is full of Boeing employees there is bound to have been some collusion and regulation capture going on.
 
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A lot of people are thinking that way.

The MAX is analogous to a car that’s prone to dangerously lurching towards the opposite side of the road so the manufacturers have put in a software kludge that nudges the steering wheel to pull it back… plus they didn’t tell anybody about this because … yes because nobody would knowingly buy or travel in such a car.
Some of the Airbus planes are fly by wire and they don't have a problem. In this case it seems to have been a design issue rather than a software bug.
 

artfoley56

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Ardillaun

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sully of miracle on the Hudson fame not sparing the rod here for the FAA or Boeing.

That’s criticism people will listen to.

In the early days of this scandal, Boeing’s supporters claimed the pilots were all happy and then the truth began to dribble out.
 

Orbit v2

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I didn’t say any of that. The simple point I was making and one that you don’t seem to be able to grasp is that the design envelope is the rules and regulations that govern aircraft design just like building regulations govern building design. Following the exact same regulations i.e. operating with the design envelope will produce any number of very different aircraft with very different performance characteristics. For example, a regulation might say the maximum wing span is 80m therefore an aircraft who’s wing span is less than 80m is within that parameter of the design envelope.
Can you point me to any such regulations? I don't think you will find any regulation relating to something so specific as the maximum span of a wing. It wouldn't make sense because the size of a wing depends completely on the specific design. The US FARs (Federal Aviation Regulations) specify mostly performance details of aircraft, not individual design elements. You might be thinking of certifications of specific designs like the 737 wings. It makes sense to certify individual assemblies like wings, because it allows upgrades of other subsystems to occur without having to recertify every nut and bolt of parts that aren't changing, multiple times.
 

Orbit v2

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A lot of people are thinking that way.

The MAX is analogous to a car that’s prone to dangerously lurching towards the opposite side of the road so the manufacturers have put in a software kludge that nudges the steering wheel to pull it back… plus they didn’t tell anybody about this because … yes because nobody would knowingly buy or travel in such a car.
That's a gross misrepresentation, albeit fed by media reports implying much the same thing. If you want to use that analogy more accurately it would say that a faulty sensor thought the car was lurching towards the opposite side of the road, when it wasn't, and intervened to send it the wrong way. The end result was the same obviously, but the difference is that the problem is 1) the faulty sensor and 2) the secret system nobody knew about. Instead, you are implying without evidence that the fundamental design of the plane is bad. Anyway, nobody is going to pay a blind bit of notice to what is said here. The safety authorities will get to the bottom of it. Nobody is going to just trust Boeing and the FAA (any more). So, if the EASA and Chinese eventually re-certify it as safe I think the public will accept it.
 


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