Friday, September 01, 2023

A Swiss Cheese of Errors

 In 2021, an F-35B fighter jet rolled off the front of the aircraft carrier HMS Queen Elizabeth during a failed take off. "Rolled" is the probably the right term, as British carriers do not use a catapult like U.S. carriers. The pilot ejected and landed on the flight deck with only minor injuries.

It was discovered later that a protective cover - part of the "red gear" because of its color - over the left engine intake had mistakenly been left in place. It was sucked into the compressor inlet of the single center-mounted jet engine, reducing power to where it was insufficient for take off.

The U.S. and its allies recovered the carcass of the F-35B. Which is good, because if they hadn't, somebody else would have.

As you would expect after totaling a bleeding edge US$80M aircraft, part of the enormously expensive and troubled U.S. F-35 program, there was a lengthy post mortem report written. I read a short (about forty pages) summary and analysis of this report this morning by Aerosurrance, a U.K. based aviation consultancy.

There is a concept in the study of organizational and complex systems failures - which is a hobby of mine that I've written about here before - called the Swiss cheese model. This is where "holes" in redundant layers of safety systems and checks (because no such system is perfect) just happen to line up at exactly the wrong time to produce a catastrophic failure.

This report was like that: maintenance crews were overworked, fatigued, and under staffed; procedures were insufficient or not followed; poor design of the red gear; no sharing of similar failures, four of which had occurred before in the U.S.; etc. (And after having previously read several long ProPublica articles about failures in the U.S. Navy that were in part due to similar issues with overwork and fatigue, I'm seeing a pattern.)

While reading this article, it occurred to me that we already have a term for Swiss cheese types of failures, and have had for eons, we just tend not to use it when it the result is tragic.

We call them "a comedy of errors".

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