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Ethiopian Airlines 737 Max crashes killing 157


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12 minutes ago, Brisketexan said:

This is the part that bothers me the most:

So....it seems that these guys did what you're supposed to (disable the MCAS)....and the stabilizer was still pushing the plane nose-down?

At this point, I'm pretty comfortable saying nope, no, no fucking way will I ever fly on a 737 Max, no matter what the FAA ends up saying.  I think there's a damned good chance this whole fiasco drives Boeing to bankruptcy.

yes - that was confusing to me as well.  My only guess is that when the MCAS automatically trims the stabilizer down and then the "power" is cut, the stabilizer stays where it is.  To get it trimmed back to pitch up, one has to move it.  They tried to do it manually but could not.  

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15 minutes ago, Brisketexan said:

This is the part that bothers me the most:

So....it seems that these guys did what you're supposed to (disable the MCAS)....and the stabilizer was still pushing the plane nose-down?

At this point, I'm pretty comfortable saying nope, no, no fucking way will I ever fly on a 737 Max, no matter what the FAA ends up saying.  I think there's a damned good chance this whole fiasco drives Boeing to bankruptcy.

Yes, but didn't they turn it back on at some point?

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6 minutes ago, C-Man said:

Yes, but didn't they turn it back on at some point?

They did, late in the game, but by then, the die was cast, it seems.

Am I correct that the "die/not die" decision point was turning the stab trim cut-out switches off early enough?  That is, once they missed that window....they were dead no matter what else they did, because the stabilizer was going to be locked in position to fly them into the ground?

Fuck.

That.

Shit.

Edited by Brisketexan
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2 minutes ago, Brisketexan said:

They did, late in the game, but by then, the die was cast, it seems.

Am I correct that the "die/not die" decision point was turning the stab trim cut-out switches off early enough?  That is, once they missed that window....they were dead no matter what else they did, because the stabilizer was going to be locked in position to fly them into the ground?

Fuck.

That.

Shit.

It's been a long time since we went over this but I think the contributing factor to the stabilizer being "locked" was that they were going too fast to turn the dial manually.

Not excusing any of this, BTW. Just trying to remember some of the specifics.

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1 minute ago, Brisketexan said:

They did, late in the game, but by then, the die was cast, it seems.

Am I correct that the "die/not die" decision point was turning the stab trim cut-out switches off early enough?  That is, once they missed that window....they were dead no matter what else they did, because the stabilizer was going to be locked in position to fly them into the ground?

Fuck.

That.

Shit.

yea - seems like a great design by Boeing.  "OK - we're gonna have the computer do something drastic that we're not gonna tell the pilots is being done and they have about 10 seconds to diagnose the issue and fix it if something goes wrong. Or else."  

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3 minutes ago, C-Man said:

It's been a long time since we went over this but I think the contributing factor to the stabilizer being "locked" was that they were going too fast to turn the dial manually.

Not excusing any of this, BTW. Just trying to remember some of the specifics.

Yep.^ Forces acting on the stabilizer (internal jackscrew) at higher speeds make it harder to turn the manual trim wheel. If you don't catch it early, you're in trouble.

Edited by retread
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Just now, C-Man said:

It's been a long time since we went over this but I think the contributing factor to the stabilizer being "locked" was that they were going too fast to turn the dial manually.

Not excusing any of this, BTW. Just trying to remember some of the specifics.

That's kind of what I recall.  In other words, the whole "MCAS is fucking up" recovery plan depends on the pilots figuring out what is going on and intervening early enough in the process so that overspeed doesn't put them in an unrecoverable situation.

Which means that the situation is effectively: "Something really fucked up is happening.  Hopefully you have great training on the issue, recall the exact process, and can execute it in a matter of seconds, otherwise you're locked into a death dive with no chance of recovery."  That seems like a REALLY bad feature for a plane to have.

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2 minutes ago, Brisketexan said:

That's kind of what I recall.  In other words, the whole "MCAS is fucking up" recovery plan depends on the pilots figuring out what is going on and intervening early enough in the process so that overspeed doesn't put them in an unrecoverable situation.

Which means that the situation is effectively: "Something really fucked up is happening.  Hopefully you have great training on the issue, recall the exact process, and can execute it in a matter of seconds, otherwise you're locked into a death dive with no chance of recovery."  That seems like a REALLY bad feature for a plane to have.

Yeah, but then Boeing would've had to take the time and spend more money to design and build a new airframe that could better accommodate the new engines. SMDH

Edited by C-Man
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2 minutes ago, Brisketexan said:

Which means that the situation is effectively: "Something really fucked up is happening.  Hopefully you have great training on the issue, recall the exact process, and can execute it in a matter of seconds, otherwise you're locked into a death dive with no chance of recovery."  That seems like a REALLY bad feature for a plane to have.

you mean you don't want that option installed?  what about the truecoat?

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Lion Air pilot did pretty well fighting MCAS with the electronic thumb switch. IIRC, MCAS rotates the stabilizer at a greater rate than the pilot's thumb switch, but I'm not sure. So, if he kept hitting that switch, could he have kept the plane in the air? FDR looks like it was a losing battle.

The pilot handed controls off to the first officer toward the end.

Quote

The sources told Reuters that the pilots remained calm for most of the flight. Near the end, the captain asked the first officer to fly while he checked the manual. 

tNvjGw.jpg

Edited by retread
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1 hour ago, Brisketexan said:

This is the part that bothers me the most:

So....it seems that these guys did what you're supposed to (disable the MCAS)....and the stabilizer was still pushing the plane nose-down?

At this point, I'm pretty comfortable saying nope, no, no fucking way will I ever fly on a 737 Max, no matter what the FAA ends up saying.  I think there's a damned good chance this whole fiasco drives Boeing to bankruptcy.

Pilots could not get the stabilizer to move because of the aerodynamic forces acting on it due to the speed of the aircraft. 

Pretty sure this was mentioned earlier in the thread. 

Edit: and it seems I didn’t realize there was another page to the thread. Retread mentioned this again before I did. 

Edited by Telegraph_it
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2 minutes ago, Telegraph_it said:

Pilots could not get the stabilizer to move because of the aerodynamic forces acting on it due to the speed of the aircraft. 

 

....which happens because the MCAS puts you into a dive, adding speed.  So it seems there's a point of no return -- once MCAS has screwed you hard enough by diving and adding speed, you can't unscrew yourself.  You have a limited window of time to interrupt the MCAS process and change the course of events....miss that short window (so, you better know what to do in mere seconds)....and you're worm food.

I don't see how Boeing survives this.

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Just now, Brisketexan said:

....which happens because the MCAS puts you into a dive, adding speed.  So it seems there's a point of no return -- once MCAS has screwed you hard enough by diving and adding speed, you can't unscrew yourself.  You have a limited window of time to interrupt the MCAS process and change the course of events....miss that short window (so, you better know what to do in mere seconds)....and you're worm food.

I don't see how Boeing survives this.

Yea that’s a feedback loop you definitely don’t want. 

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2 minutes ago, Telegraph_it said:

You’d be silly to not fly on the max because 1) it will now be the safest plane ever and 2) you won’t know it’s a max anyway. Marketing will do its damndest to be sure if it. 

If I see fat engines under a 737 Boeing....I ain't going.

I'm f'n serious.  "Fix" my ass.  Sorry, I won't ever be able to bring myself to trust that aircraft again.  Boeing built something that shouldn't have been built, it had an inherent flaw that they tried to compensate for, and the choice is either the flaw kills you or the compensation mechanism kills you.  Here's the solution - build a different damned plane without the flaw, and we won't go down that road at all.

Products, and a brand, are only as valuable as the public goodwill towards them.  Boeing just blew it.  All of it.

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The Ethiopian plane was going too fast to overcome aerodynamic forces on the stabilizer because the crew left the plane in TOGA power for most of the flight, and not because they were in a dive. 

 

And yes, Boeing mgt should be facing litigation for their role in shortcutting and undermining the certification process. 

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2 minutes ago, Bobby_Batronic said:

The Ethiopian plane was going too fast to overcome aerodynamic forces on the stabilizer because the crew left the plane in TOGA power for most of the flight, and not because they were in a dive. 

So, why do you think they left it in TOGA power?  Because they thought they needed power to climb to overcome the dive?

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Boeing personnel were authorized to work on behalf of the FAA. Tasks were divided up. As the MCAS was tweaked on simulators, the engineers adjusted the maximum rotation of the stabilizer. Most engineers thought it was 0.6 degrees. Turns out, MCAS had been set up to be able to move the stabilizer 2.5 degrees each time. It was also authorized to actuate multiple times.

That info was not included in the System Safety Analysis submitted for the MAX's final approval. IIRC, it's supposed to include everything that is changed.

"After the Lion Air Flight 610 crash, Boeing for the first time provided to airlines details about MCAS. Boeing’s bulletin to the airlines stated that the limit of MCAS’s command was 2.5 degrees.

That number was new to FAA engineers who had seen 0.6 degrees in the safety assessment.

The FAA believed the airplane was designed to the 0.6 limit, and that’s what the foreign regulatory authorities thought, too,” said an FAA engineer. “It makes a difference in your assessment of the hazard involved.”

Quote

The safety analysis:

Understated the power of the new flight control system, which was designed to swivel the horizontal tail to push the nose of the plane down to avert a stall. When the planes later entered service, MCAS was capable of moving the tail more than four times farther than was stated in the initial safety analysis document.

Failed to account for how the system could reset itself each time a pilot responded, thereby missing the potential impact of the system repeatedly pushing the airplane’s nose downward.

Assessed a failure of the system as one level below “catastrophic.” But even that “hazardous” danger level should have precluded activation of the system based on input from a single sensor — and yet that’s how it was designed.

After the Lion Air Flight 610 crash, Boeing for the first time provided to airlines details about MCAS. Boeing’s bulletin to the airlines stated that the limit of MCAS’s command was 2.5 degrees.

That number was new to FAA engineers who had seen 0.6 degrees in the safety assessment.

“The FAA believed the airplane was designed to the 0.6 limit, and that’s what the foreign regulatory authorities thought, too,” said an FAA engineer. “It makes a difference in your assessment of the hazard involved.”

 

 

The higher limit meant that each time MCAS was triggered, it caused a much greater movement of the tail than was specified in that original safety analysis document.

The former FAA safety engineer who worked on the MAX certification, and a former Boeing flight controls engineer who worked on the MAX as an authorized representative of the FAA, both said that such safety analyses are required to be updated to reflect the most accurate aircraft information following flight tests.

“The numbers should match whatever design was tested and fielded,” said the former FAA engineer.

But both said that sometimes agreements were made to update documents only at some later date.

https://www.seattletimes.com/business/boeing-aerospace/failed-certification-faa-missed-safety-issues-in-the-737-max-system-implicated-in-the-lion-air-crash/

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19 minutes ago, Brisketexan said:

So, why do you think they left it in TOGA power?  Because they thought they needed power to climb to overcome the dive?

Best guess?  Initial reaction to the stall indications, and then it seems they forgot about it with everything happening on the flight deck. They were flying for 6 minutes so it wasn’t a dive until then end. 

There is validity in the thought that they may have been using underslung engines to overcome the pitch down as it’s something that is taught, but the CVR didn’t seem to indicate that was the train of thought at all. The pilots correctly identified that they had a left AOA vane issue, but then let the plane get away from them in the confusions and procedures that followed. Increasing speed in a strong out of trim condition is not usually the best answer.

What is a lot of effort at 220kts is uncontrollable at 380kts. Remember that the forces acting on the flight surfaces act as a square of the speed. That’s probably worded poorly, but twice the speed results in 4 times the force. 

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1 minute ago, Bobby_Batronic said:

Best guess?  Initial reaction to the stall indications, and then it seems they forgot about it with everything happening on the flight deck. They were flying for 6 minutes so it wasn’t a dive until then end. 

There is validity in the thought that they may have been using underslung engines to overcome the pitch down as it’s something that is taught, but the CVR didn’t seem to indicate that was the train of thought at all. The pilots correctly identified that they had a left AOA vane issue, but then let the plane get away from them in the confusions and procedures that followed. Increasing speed in a strong out of trim condition is not usually the best answer.

What is a lot of effort at 220kts is uncontrollable at 380kts. Remember that the forces acting on the flight surfaces act as a square of the speed. That’s probably worded poorly, but twice the speed results in 4 times the force. 

Thanks.  And seriously, I appreciate your commentary on this thread.

Seems like the failure here (that is, the sensor failure and the programmed MCAS response) puts pilots in a position where they've got to process a lot of counter-intuitive shit in a short amount of time.  Which is, umm, not an optimal design.

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7 minutes ago, Brisketexan said:

Thanks.  And seriously, I appreciate your commentary on this thread.

Seems like the failure here (that is, the sensor failure and the programmed MCAS response) puts pilots in a position where they've got to process a lot of counter-intuitive shit in a short amount of time.  Which is, umm, not an optimal design.

Agreed and thank you. 

There’s a lot of training going on now to help address some of the confusion that these kind of failures can produce. Kinda getting pilots to analyze the situation outside of the indications.

The Ethiopian crew had initial stall indications  with the stick shaker and associated warnings, but the plane was accelerating and climbing and showing no signs of a buffet. So there’s a whole slew of indications, sounds and feels flying them in to it not being a stall. Which they figured out. They even ran the correct emergency procedure, but never connected it to the MCAS issue, and flat forgot their power setting. 

I just finished my expanded envelope training where we hand flew the plane almost exclusively in the sim with all sorts of airspeed failures, unexpected stall conditions and recovery from really unusual attitudes. Like 45 degrees nose down and 120 degrees of bank while recovering without over-stressing the plane. Fantastic training, that really gets the thinking cap to working. 

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1 hour ago, HoustonFrog said:

What’s amazing is that nobody is headed to trial. It’s fucking obvious what was going on at Boeing. True insanity

Not amazing. Infuriating, yes. After watching the whole sub-prime robo-signing, packaging shit as AAA paper, etc. and nobody, NOBODY, went to prison for it, this is what I expect. The government doesn’t put officers of big corporations in prison. Only slaps a fine on the company (or bails them out if needed). The business of the American government is being friendly to the big corporations, no matter the moral hazard.

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Wishing for Boeing to go out of business is ludicrous.
Yeah, shoot the assholes in charge who made those fatal decisions, but to make the company go away is off the wall.

I don’t want them to go the bankruptcy (although at this point, I can’t make myself care). I just think they will.
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It seems that a common thread in airplane catastrophes is “sensory overload”. They probably spent a good deal of mental effort trying to figure why the computer was screaming STALL at them. I’m guessing that if you are a pilot and the computer is saying stall, you might not think about reducing thrust so that you can turn a wheel against the aerodynamic forces.

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Interesting read as to why ET302 was flying so fast, and why the pilot's electronic trim commands were short bursts, as opposed to longer durations.  https://leehamnews.com/2019/04/05/bjorns-corner-et302-crash-report-the-first-analysis/

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The insufficient trim mystery after re-activation of Electric Trim
After 7 PF commands Electric Trim Nose Up in two short cycles. I asked my selves (as did others) why these short trims? They are fighting to get the nose up to the extent they risk switching in the Electric Trim again. Then why not trim nose up continuously or for at least long cycles once Electric Trim is there? It took me several hours to find an explanation. Here my take:

To understand the blip trims one must have flown fast jets at low altitude. At the speed ET302 is flying, 360kts, it’s hypersensitive to trim. The least trim action and the aircraft reacts violently. Any trimming is in short blips.

As PF holds the nose up with a very high stick force, now for a long time, he’s sensitivity to release stick with trim is not there (this is what Pilots do when they trim nose up, otherwise the aircraft pitches up fast). He trims therefore in short blips and has difficulty to judge the trim effect he has achieved. His is not flying on feel. He can’t, he is severely out of trim, holding on to the Yoke with a strong pull force.

Anyone who has flown a grossly out of trim aircraft at high speeds knows your feel is compromised. The sensors you have to rely on are your eyes, not your hands.

PF has the horizon glued to read the aircraft. The result is the short nose-up trims we see. The nose goes up and the stick force needed is reduced. His judgment is; this is enough for now, it was a powerful response. Any MCAS attack I now trim against, then I correct my trim if I need to.

But the aggressive MCAS, trimming with a speed 50% higher than the pilot and for a full nine seconds, kicks in at 8 with a force they didn’t expect. Speed is now at 375kts and MCAS was never designed to trim at these Speed/Altitude combinations. Dynamic pressures, which governs how the aircraft reacts to control surface movements, is now almost double it was when last MCAS trimmed (Dynamic pressure increases with Speed squared).

Quote

The throttles are left at 94% thrust for the whole flight. This is higher than normal but this is a high takeoff. At 7,600ft it is a full 2,200ft higher than Denver, which is the US Benchmark for high takeoffs. And with Stick Shaker and IAS disagree you keep high thrust and fly a slow climb (the IAS disagree is present in the traces but not mentioned in the report specifically. We don’t have all the Crew callouts and discussions present in the report is my conclusion).

 

Edited by retread
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I don’t think they were getting an IAS disagree. The angle of attack was incorrect. Not the airspeed indicator. 

In the bus the unreliable airspeed procedure below thrust reduction altitude is it turn off all the automation, pitch up to 15 degrees and apply Toga power. And then you reduce it it 10 degrees and climb power between thrust reduction altitude and 10,000 feet. But the Ethiopian crew wasn’t trying to climb at an IAS. The CA repeatedly tried to turn the autopilot on, and both pilots realized it was a left AOA van issue. 

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2 hours ago, Bobby_Batronic said:

Agreed and thank you. 

There’s a lot of training going on now to help address some of the confusion that these kind of failures can produce. Kinda getting pilots to analyze the situation outside of the indications.

The Ethiopian crew had initial stall indications  with the stick shaker and associated warnings, but the plane was accelerating and climbing and showing no signs of a buffet. So there’s a whole slew of indications, sounds and feels flying them in to it not being a stall. Which they figured out. They even ran the correct emergency procedure, but never connected it to the MCAS issue, and flat forgot their power setting. 

I just finished my expanded envelope training where we hand flew the plane almost exclusively in the sim with all sorts of airspeed failures, unexpected stall conditions and recovery from really unusual attitudes. Like 45 degrees nose down and 120 degrees of bank while recovering without over-stressing the plane. Fantastic training, that really gets the thinking cap to working. 

I have really enjoyed your opinions on this. Now that some time has passed and more things are learned have you changed your opinion? To me Boeing is looking worse. 

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Boeing survives this because they are only one of two aircraft manufacturers in the world and the only one in the US. They probably shouldn’t and their execs should be all loaded on a Max right now and given the death by exile treatment (here’s the keys you fuckers fly it) but the US govt ain’t going to cede having a manufacturer in the US.

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10 hours ago, Telegraph_it said:

You’d be silly to not fly on the max because 1) it will now be the safest plane ever and 2) you won’t know it’s a max anyway. Marketing will do its damndest to be sure if it. 

Said the de Havilland Comet.

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11 hours ago, Surly Bevo said:

Boeing survives this because they are only one of two aircraft manufacturers in the world and the only one in the US. They probably shouldn’t and their execs should be all loaded on a Max right now and given the death by exile treatment (here’s the keys you fuckers fly it) but the US govt ain’t going to cede having a manufacturer in the US.

Embraer and Bombardier provide fleet for Delta, Jet Blue, Frontier, Alaska, American, United and many others.

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6 hours ago, Bobby_Batronic said:

There’s 5500 of them ordered. Airbus couldn’t make up the difference in their wildest dreams. The Max will not only survive, but will be a mainstay in the skies. 

If you were in charge of fixing/removing MCAS, how would you handle it? Appreciate all the good insights from the pilots itt.

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I don’t think they were getting an IAS disagree. The angle of attack was incorrect. Not the airspeed indicator.  In the bus the unreliable airspeed procedure below thrust reduction altitude is it turn off all the automation, pitch up to 15 degrees and apply Toga power. And then you reduce it it 10 degrees and climb power between thrust reduction altitude and 10,000 feet. But the Ethiopian crew wasn’t trying to climb at an IAS. The CA repeatedly tried to turn the autopilot on, and both pilots realized it was a left AOA van issue. 

 

You'll get unreliable airspeed and shaker on the side the AoA vane shears off. We had one in Panama city 2 months ago. It's a miracle everyone survived / sarcasm.

 

There's enough evidence that poor piloting contributed to the accident which will allow the FAA to recertify with initial computer based training. Then everyone will get sim training on their next scheduled recurrent training event. My opinion only. Other countries may have other ideas. We don't even own a MAX sim yet, of course the MAX9 wasn't involved in either accident.

 

 

 

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I frequently travel for business and pleasure. Under no circumstances would I ever step foot on a max. Rebrand all they want as mentioned above  fat engines and winglets are a giveaway. Luckily in my region I end up flying Delta and the A220 is looking good. Hopefully southwest switches up and purchase some as well.

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7 hours ago, Kepler62f said:

I frequently travel for business and pleasure. Under no circumstances would I ever step foot on a max. Rebrand all they want as mentioned above  fat engines and winglets are a giveaway. Luckily in my region I end up flying Delta and the A220 is looking good. Hopefully southwest switches up and purchase some as well.

Usually you have to purchase your ticket before getting a look at the plane.

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2 hours ago, Fudge Nuggets said:

Usually you have to purchase your ticket before getting a look at the plane.

I see the price difference between flex and firm fares going up. Similarly, I don't see the "No 737 Max" checkbox appearing on OTAs. Travellers will be resigned to flying it once MCAS is removed. 

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Not amazing. Infuriating, yes. After watching the whole sub-prime robo-signing, packaging shit as AAA paper, etc. and nobody, NOBODY, went to prison for it, this is what I expect. The government doesn’t put officers of big corporations in prison. Only slaps a fine on the company (or bails them out if needed). The business of the American government is being friendly to the big corporations, no matter the moral hazard.


Don’t disagree but there’s something far more evil about screwing around with the safety of metal tubes carrying hundreds of people at rapid speed where death is basically the only option if there’s a failure.

Screwing people out of money is criminal and should be prosecuted, but sticking people in an unsafe plane (something that makes many people very nervous as is) is just evil

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