tank training
Used to work in B707 fuel tanks 30 years ago, and no training certificates needed then.
Escape rescue equipement, I cannot think how it works, as I recall having to crawl around tanks bending and twisting through ribs, baffles, pipes and lumps and having to remember the order one got in to reverse it to get out.
OK in tank if well vented, as nice and clean, but then if there is riveting going on it is noisy.
Worst bit if after taking minutes to get up to the coal face some one unplugs the lead lamp to put his in, and you have to crawl out again to reconnect your light.
Must be a long time I worked in tanks as the hair is growing again on my knees.
Centre tank on B747 can nearly stand up straight in and get a whole party of people in there as well. Other tanks one arm your head and a torch and the tank is full up.