What is the correct enclosed space rescue procedure?

The single most important rule of enclosed space rescue is that nobody, however strong the instinct, should ever rush in unprotected to help a person who has collapsed inside, because whatever atmosphere overcame the casualty will overcome an unprotected rescuer just as quickly, and the tragic, recurring pattern in enclosed space fatalities worldwide is multiple deaths from exactly this instinct rather than from the original single casualty.

When someone collapses inside an enclosed space, the correct first action is to raise the alarm immediately rather than enter: shout for help, inform the bridge or duty officer without delay, and sound the designated alarm so that the trained emergency team and rescue equipment are mobilized at once. Everyone else on scene should stay at the entrance, keep the casualty in view if that can be done safely from outside the space, and begin readying the rescue equipment rather than attempting entry themselves.

The rescue itself is carried out only by a properly organized and trained team wearing self contained breathing apparatus, so their air supply is entirely independent of the contaminated space, never with filter type escape sets which do not protect against oxygen deficiency. The team uses the retrieval equipment every ship is required to keep ready for this purpose: full body harnesses, lifelines, and a tripod, davit or fixed winch arrangement positioned over the access point to haul an incapacitated casualty vertically out of a tank or void without rescuers themselves having to enter deeply, along with resuscitation equipment and a reliable means of communication, radio or voice, between the rescue team and those coordinating from outside.

Where conditions allow, the space is ventilated to improve the atmosphere while the rescue team dons breathing apparatus and prepares, though rescue should not be delayed indefinitely waiting for ventilation if the casualty's condition demands immediate action. The standby person, whose role is assigned before any routine entry into an enclosed space, is central to preventing this situation becoming worse: their entire job is to remain at the entrance, never enter themselves under any circumstances, and instead raise the alarm and coordinate the response, which is precisely why every entry, however routine it seems, requires a standby person posted and briefed beforehand.

Once the casualty is recovered into fresh air, first aid and resuscitation are administered immediately by crew trained in it, and medical advice is sought without delay, whether from the ship's medical officer, a shoreside telemedical service, or by diverting to the nearest port if the condition is serious. Because a genuine rescue unfolds fast and chaotically and there is no time to work out the plan from scratch in the moment, SOLAS requires ships to hold enclosed space entry and rescue drills at regular intervals, commonly every couple of months, specifically so that the equipment is familiar, the team roles are rehearsed, and the crew's trained response overrides the fatal instinct to rush in unprotected.