Robotic Air-slot Volumetric Inspection System (RAVIS) is a marsupial crawler, with a mother robot carrying and releasing smaller robotic inspection devices. The larger crawler enters the carbon steel tank through a riser, clings to the primary tank wall with magnets, travels along the sidewall, and launches the smaller inspection tools into the air slots. This uses the ultrasonic testing crawler fleet used for regular tank inspections and features a new cable push-and-pull attachment that guides and pushes a camera via its rigid tether through the air slots.