Nobody enters the tank

The honest case for indoor drones is not that they fly. It is that the confined space entry they replace was always the real cost.

Ask what a tank or boiler inspection costs and the quoted number is usually the inspector's time. The true number lives around it: the permit, the attendant at the hatch, the rescue coverage on standby, the draining and ventilating and gas testing, and in the worst cases the scaffolding built inside a vessel so a person can get eyes on a weld. The inspection is minutes. The entry is the project.

That is the arithmetic an indoor drone changes. A collision tolerant aircraft goes through the hatch instead of a person, and the entire apparatus that exists to keep that person alive stops being necessary for the first look. The value is not glamorous and it is not about flight. It is subtraction: an entry that does not happen, a permit that is not pulled, a scaffold that is not built.

Honesty requires the other half. A drone gathers imagery; it does not certify anything. Where a code inspection requires an inspector's judgment or a contact measurement, the flight is a screening pass that tells you where to send the person, not a substitute for the person. Many programs land exactly there and are glad to: fly first, then enter only where the footage says entry is worth it. Fewer entries, better targeted.

Also true: the footage is only as good as the plan for reading it. A thousand images of a tank interior are not an inspection until someone maps them to the asset and writes findings. Buy the review workflow with the aircraft, or the deliverable is a hard drive.

The buyers who get this right scope it as a safety project that happens to use a drone, not a drone project that mentions safety. Their justification is written in entries avoided and permits not pulled, numbers their own safety office already tracks. Framed that way, the aircraft is almost incidental, which is exactly how a good equipment decision should feel.