ALARP Documentation Built From Continuous Fatigue Metrics

A UKCS safety case reviewer asks the duty holder for the ALARP evidence on fatigue risk. The duty holder produces a 40-page narrative with references to shift patterns, training, and rota policy. The reviewer asks for the continuous metrics that prove the argument. The duty holder has none. This post shows how garden data becomes ALARP evidence.

A UKCS safety case revision landed on a reviewer's desk in late 2025. The duty holder — a mid-sized drilling contractor operating three semi-subs in the North Sea — had produced a 40-page narrative on fatigue risk. The document covered shift patterns, rest-period compliance, training records, and a policy statement on fatigue management. The reviewer asked one question: "Where are the continuous metrics that demonstrate the argument you're making?"