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

This seems like mostly how it ought to work -

* There were two unusual events in very short order

* Someone quickly noticed and gave the order to go to ground stop

* The problem was figured out quickly and a work-around was developed

* Flights Resumed after successfully deploying the work around to the 'production process'

* A patch was quickly developed and deployed once the underlying bug was uncovered.

I think everyone (but perhaps the developers) comes out looking like a champ.

Now, do I think telling pilots what thrust they should use to take off is wise? I dont know - I'm not a pilot, and I'd want pilots feelings on the matter before commenting further, but it feels to me like a loss of authority that would make me uncomfortable - particularly if I was held to account for undetected failures.

The other part that I'd note here, is process is just as important as software could process alone have caught this failure without the tail strikes? possibly, and its something worth looking into further - but only if it doesn't add an unacceptable workload burden to pilots workload that could otherwise compromise safety further.

The purpose of telling pilots thrust was to save money and fuel. It’s a “least viable” optimization.

>“The goal is to lower the power used on takeoff,” he said. “That reduces engine wear and saves money” on fuel and maintenance.

>Flights to Hawaii are typically full, with lots of baggage and a full load of fuel for the trip across the ocean. The planes are heavy.

> That morning, a software bug in an update to the DynamicSource tool caused it to provide seriously undervalued weights for the airplanes.

>Peyton added that even though the update to the DynamicSource software had been tested over an extended period, the bug was missed because it only presented when many aircraft at the same time were using the system.

> Both planes headed down the runway with less power and at lower speed than they should have. And with the jets judged lighter than they actually were, the pilots rotated too early.

>The data “confirms that the airplane was safely airborne with runway remaining and at an altitude by the end of the runway that was well within regulatory safety margins. Both aircraft got airborne well within safety limits despite the lower thrust.

It’s also probably lucky that two Hawai’i bound flights both didn’t notice the discrepancy, or two bumps wouldn’t have bee as suspicious. Interesting that someone cited divorce and sleep examples as emotional pleas, reassuring us they are only human.

Like all complex failures at least 5 things had to happen. Software update that morning, some kind of hard to simulate resource issue in processing, overweight flights, pilot not pricing plane data appeared light, pilot turning early despite low speed, two in a row.

The article says the reason the weights were wrong was due to high load on the DynamicSource software. Seems more like a concurrency issue

> Peyton added that even though the update to the DynamicSource software had been tested over an extended period, the bug was missed because it only presented when many aircraft at the same time were using the system.

That seems horribly wrong to me. I can understand software being slow under load, but being wrong under load sounds like a horrible internal architecture problem.