Engine room operated without engineer watch present, relying on automation, alarms, and a duty engineer on call.
Regulatory detail & full definition
Required minimum class notation 'UMS' or '24-h UMS'. Must have data logger, fire/bilge/water-ingress detection, dead-man alarm tied to the duty engineer's cabin, machinery-space CCTV. Watch is suspended at sea between morning rounds; stand-by by VHF/pager. Exempt for tanker cargo operations and when operating in restricted waters.