Incident: American B38M near Nassau on Mar 29th 2021, pitch trim issue/failure • Hacker News Board

Re: Incident: American B38M near Nassau on Mar 29th 2021, pitch trim issue/failure

#121

Post by rualca » Wed, Mar 31, 2021, 11:39 PM UTC

jryle70 wrote: post #114

martimarkov wrote: post #10

Earlier quoted context omitted.

I agree but it’s like the galaxy phone that had the battery issue. It just killed confidence with the consumer. The investigation (and what we learned form it) into Boeing also didn’t help with confidence levels. After a few new iterations nobody talks about the battery anymore. I’m not so sure how Boeing can turn this around relatively quickly.

Southwest just placed a large order for 737MAX-7 two days ago - [0]. 100 firm orders plus 155 options. They may get a great deal from Boeing for all we know, but placing a large order during this terrible time for the airlines is a bet on the future of MAX as well as the industry recovery. [0] - https://www.cnbc.com/2021/03/29/southwest-airlines-adds-100-... Meta note, this relatively frequent aircraft incident gets…

> They may get a great deal from Boeing for all we know, but placing a large order during this terrible time for the airlines is a bet on the future of MAX as well as the industry recovery.

Is this supposed to mean anything? To me it reads like an airline managed to get a massive discount on inventory that a struggling aircraft manufacturer hasn't been able to move for about a year due to their repeated problems with safety and accountability, which led the whole world to drop their orders.

Re: Incident: American B38M near Nassau on Mar 29th 2021, pitch trim issue/failure

#122

Post by slacktide » Thu, Apr 01, 2021, 12:41 AM UTC

qubit000 wrote: post #110

Boeing has lost the public trust not only in the US, but internationally. Inherent instability aside, fact remains the general perception is that Boeing retrofitted engines too large for 50yr plane design necessitating structural modifications which compromised its flight worthiness. As a result, software had to be written to compensate for this, which unbelievably, relied on input from a single sensor--iow, single p…

Boeing did not get into this position overnight. After the massive cost and schedule overruns on the 787 program, they were far too cash-poor to fund the development of a clean-sheet design, hence the re-warmed 737. The 787 itself was a huge experiment in outsourcing both the costs and risks of aircraft development. It turns out you can outsource cost, but the prime contractor always owns the risk. Dr. John Hart-Smith published an excellent white paper warning of this while the precursor to the 787 was still in development, shortly after the Boeing-McDonnell Douglass merger.

https://www.google.com/search?q=Outsourced+Profits+%E2%80%93...

Re: Incident: American B38M near Nassau on Mar 29th 2021, pitch trim issue/failure

#123

Post by Closi » Thu, Apr 01, 2021, 8:44 AM UTC

cryptonym wrote: post #98

Closi wrote: post #78

Earlier quoted context omitted.

This is true to some extent, although the difference in safety is so large that in the example you are still more likely to die from a car accident on your way to Point Reyes than your flight to New York. Deaths from car accidents per 100 million miles driven: 1.33 Deaths from plane accidents per 100 million miles by plane: 0.0077 (Note above statistics are from the US) In your example, California to New York would b…

What you say is true but coarse statistics doesn't reflect actual situation. You would have to compare 737 MAX deaths per mile to OP car deaths per mile. Maybe taking into account that hopefully OP doesn't speed, drink, text, watch harry potter... Don't know if deaths includes pedestrian or bikes killed by cars, could be irrelevant if you only compare your odds to be alive after journey. I'd also expect a recent car…

Apologies, I thought OP was just talking about flying in general rather than specifically the 737 max but I have re-read and it's clear. I think I just forgot as I was writing the response!

> Don't know if deaths includes pedestrian or bikes killed by cars, could be irrelevant if you only compare your odds to be alive after journey.

I agree this could be debated, but I don't think it's too useful to say "The journey was safer because rather than kill the person travelling it only killed a random pedestrian".

Re: Incident: American B38M near Nassau on Mar 29th 2021, pitch trim issue/failure

#124

Post by jakeogh » Thu, Apr 01, 2021, 10:12 AM UTC

Toutouxc wrote: post #105

jakeogh wrote: post #102

Earlier quoted context omitted.

If I understand correctly, ultimately they could not overcome it, and after many dives, the computer succeeded in crashing the aircraft... it's practically irrelevant long the pilots were able to overcome it. The base issue is that it was even possible for the control of humans with hundreds of lives in their hands to be overridden by a set of predefined instructions.

It's very relevant that the plane was flying long enough for the pilots to go through the runaway trim checklist, which, if they went through the procedure, would have probably saved the plane. They didn't go through the checklist, because AFAIK they didn't realize immediately that it's a runaway trim situation, because of imprecise and/or conflicting indications in the cockpit.

It's got control of the trim wheels, and it's plunging the aircraft to the ground with nonsense trim settings. Right?

Needing to consult the manual to disable that input is eh... not optimal.

They physically could not trim the aircraft, and even worse (as if), could not -trivially- prevent changes to that trim.

Should humans on the line have ultimate control of the surfaces or not? If so, how many steps through "complicated checklists" should be required to get control of a basic setting like trim?

The base issue is that it was even possible for the control of humans with hundreds of lives in their hands to be overridden by a set of predefined instructions.

Re: Incident: American B38M near Nassau on Mar 29th 2021, pitch trim issue/failure

#125

Post by cratermoon » Fri, Apr 02, 2021, 5:28 AM UTC

salawat wrote: post #68

manigandham wrote: post #33

Earlier quoted context omitted.

That's incorrect. All planes have a relationship with thrust and pitch based on multiple factors (size, weight, speed, wing configuration, altitude, etc). The aircraft was perfectly sound. The problem was software designed to alter the flight profile automatically to minimize the differences and new training required (and was allowed to override manual inputs). Any pilot with full training of this specific plane with…

What the poster was more likely referring to was the uncertifiable behavior that would occur without MCAS during a wind-up turm or during descent whereby stick control forces would slacken on the way to stall instead of requiring steadily increasing pressure on the control column to bring the plane to a stall due to extra lift from the forward nacelles. While technically a pilot could deal with it, aircraft that demo…

It seems to me that the folks here arguing that the 737 Max is safe have a definition of "safe" that would satisfy a military test pilot. I'm sure that even without MCAS a top-notch pilot could fly the Max without incident, but when it comes to passenger aircraft safety, the bar is considerably higher.