I remember reading closer to the time they banned smoking on planes of engineers complaining that when people stopped smoking on planes it made it much harder t

I remember reading closer to the time they banned smoking on planes of engineers complaining that when people stopped smoking on planes it made it much harder to inspect for hairline cracks! The smoke would highlight the cracks yellow. Can't find any first hand sources now but this article touches on it: https://www.lesswrong.com/posts/opaRvBMRcuk7pWbZD/smoking-cigarettes-in-airplanes-made-the-airplanes-safer https://www.lesswrong.com/posts/opaRvBMRcuk7pWbZD/smoking-ci...