US Army
U.S. Army Reserve Pvt. Kenneth Collins, 376th Engineer Firefighter Detachment, pulls himself from a confined space familiarization tube at Combat Support Training Exercise (CSTX) 86-18-02 at Fort McCoy, Wis., August 13, 2018.
A space is confined if it has a limited or restricted entry or exit point.
"Confined spaces include, but are not limited to, tanks, vessels, silos, storage bins, hoppers, vaults, pits, manholes, tunnels, equipment housings, ductwork, pipelines, etc.," $4 to the Occupational Safety and Health Administration.
And the US military trains for all different kinds of scenarios in such spaces.
Here's what they do.