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After Alaska Airlines planes bump runway, a scramble to ‘pull the plug’

seattletimes.com

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Re: After Alaska Airlines planes bump runway, a scramble to ‘pull the plug’

#51

Post by kube-system »

1101010010 wrote: post #21

Lots of blame to pass on the software, but the real culprit is spelled out clearly in the middle of the article: > the computer then calculates just the right amount of engine thrust so the pilots don’t use more than necessary. “The goal is to lower the power used on takeoff,” he said. “That reduces engine wear and saves money” on fuel and maintenance. This is not an accident, but rather a feature of capitalism, this…

It doesn't matter if you used full power on every takeoff, if you rotate early, you rotate early. Vr is based on weight (and other factors).

Re: After Alaska Airlines planes bump runway, a scramble to ‘pull the plug’

#52

Post by 1101010010 »

brookst wrote: post #39
1101010010 wrote: post #21

Lots of blame to pass on the software, but the real culprit is spelled out clearly in the middle of the article: > the computer then calculates just the right amount of engine thrust so the pilots don’t use more than necessary. “The goal is to lower the power used on takeoff,” he said. “That reduces engine wear and saves money” on fuel and maintenance. This is not an accident, but rather a feature of capitalism, this…

You think it would be more ideal to wear out engines sooner and burn more fossil fuels? If efficiency is the curse capitalism brings us, I’m feeling a little better about it.

If efficiency is the goal, packing people into a standing-only flight would also save fuel and reduce wear, I suppose you don't see any problem with that either?

https://www.theguardian.com/business/2012/feb/28/ryanair-sta...

Re: After Alaska Airlines planes bump runway, a scramble to ‘pull the plug’

#53

Post by Merad »

I was under the impression that SOP for most aircraft was to take off at full power, and if you happen to be lightly loaded you just get into the air faster. Was I wrong, or is this a recent change? If so, it seems like a concerning way for airlines to cut costs. Having excess power available at take off means there's a greater margin for error to handle emergencies (engine failure, bird strike, etc.).

Re: After Alaska Airlines planes bump runway, a scramble to ‘pull the plug’

#54

Post by roamerz »

Seems like any modern jet would have a load sensing system built into the landing gear. Something so critical such as takeoff weight would be both estimated by a software system and compared to an onboard system for redundancy. Any discrepancy beyond a set limit would turn on a warning light.

Re: After Alaska Airlines planes bump runway, a scramble to ‘pull the plug’

#55

Post by jcutrell »

zaroth wrote: post #25
1101010010 wrote: post #21

Lots of blame to pass on the software, but the real culprit is spelled out clearly in the middle of the article: > the computer then calculates just the right amount of engine thrust so the pilots don’t use more than necessary. “The goal is to lower the power used on takeoff,” he said. “That reduces engine wear and saves money” on fuel and maintenance. This is not an accident, but rather a feature of capitalism, this…

Calculating the appropriate amount of liftoff thrust based on the weight of the plane is universal for flight ops. This feature of capitalism caused the money to be invested to achieve this efficiency, and also the systems and processes in place to ensure it was implemented properly; with sanity checks, authoritative oversight to halt ops when something was determined to be off, manual backup systems in place and wel…

I’m not sure that thrust calculation is actually incredibly common. I’d be curious what the handbook on these aircraft say, but common practice for many aircraft is full thrust on takeoff - rarely is there a negative safety penalty for too much thrust. Just an earlier rotate.

Comment OP isn’t wrong entirely - this is the result of an economic decision. Not without it’s good effects - both can be true, but this is not a safety optimization by any means.

Many aviation accidents can be traced back to capitalistic pressure - cost saving on inspections, time saving for flow, etc. It’s appropriate to ask whether this is true here as well.

Re: After Alaska Airlines planes bump runway, a scramble to ‘pull the plug’

#56

Post by sopooneo »

ceejayoz wrote: post #27
justinclift wrote: post #14

With Boeing's recent 737 family history (MAX fiasco, etc), it's very concerning to see "software errors" still happening in operation. :(

How does a "SaaS Founder, Senior DevOps Engineer" get the idea that software errors are entirely avoidable? This story is about the system working well. Detected immediately via well-trained and alert humans, someone had and used their individual authority to ground the entire airline for safety reasons, mitigated with a workaround 20 minutes later, permanently fixed within five hours, and new tests implemented to ac…

I'm with you that a couple layers of the "safety in depth" worked impressively well here. But a bug of this types points to egregiously bad process and standards with the software vendor. And the airlines or FAA should have audits to catch that well upstream of this incident.

Re: After Alaska Airlines planes bump runway, a scramble to ‘pull the plug’

#57

Post by jcutrell »

CPLX wrote: post #38
1101010010 wrote: post #21

Lots of blame to pass on the software, but the real culprit is spelled out clearly in the middle of the article: > the computer then calculates just the right amount of engine thrust so the pilots don’t use more than necessary. “The goal is to lower the power used on takeoff,” he said. “That reduces engine wear and saves money” on fuel and maintenance. This is not an accident, but rather a feature of capitalism, this…

That’s a feature of engineering. Figuring out what performance and safety requirements are and then optimizing the resources required to meet those requirements is what engineering is for. The influence of capitalism would be on the requirements. But assuming the requirements are well-considered trying to minimize fuel and engine usage to meet those requirements is a good thing.

I think this is pretty subjective. You could also say that engineering should be used to increase the margin of safety (what is often labeled over-engineering).

If the engineering requirement is “do something that brings you close to the margin of safety in order to save resources”, is that not an influence of capitalism?

Re: After Alaska Airlines planes bump runway, a scramble to ‘pull the plug’

#59

Post by fortran77 »

loeg wrote: post #20
fortran77 wrote: post #3

[flagged]

Both aircraft seat about 180 pax. To be 20,000 lbs off in your hypothesis, each passenger would have to be 110 lbs heavier than modeled, on average. For 30,000 lbs, 165 lbs.

See: https://airinsight.com/the-pending-new-faa-weight-balance-ru...

There were recent changes to the weight and balance rules because of increased weight. It's certainly possible this was a factor.

Re: After Alaska Airlines planes bump runway, a scramble to ‘pull the plug’

#60

Post by abudabi123 »

ceejayoz wrote: post #27
justinclift wrote: post #14

With Boeing's recent 737 family history (MAX fiasco, etc), it's very concerning to see "software errors" still happening in operation. :(

How does a "SaaS Founder, Senior DevOps Engineer" get the idea that software errors are entirely avoidable? This story is about the system working well. Detected immediately via well-trained and alert humans, someone had and used their individual authority to ground the entire airline for safety reasons, mitigated with a workaround 20 minutes later, permanently fixed within five hours, and new tests implemented to ac…

The SpaceX rockets launch routinely with automation at takeoff and landing. There is no need for human heroic drama in the loop when the software is AAA grade.
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