What is a STEP chart?

A STEP (Sequentially Timed Events Plotting) chart maps each actor's actions on a horizontal timeline, exposing convergence points where multiple actors interact. It is essential for multi-party incidents like vessel collisions or process upsets.

Developed by Kingston in the 1980s for transport accidents, STEP charts solve the problem narrative reports cannot: showing who did what, in parallel, at exactly which second. Multi-actor incidents — bridge collisions, control-room handovers, simultaneous operations — become legible.

BY RiskoPilot Editorial Team · REVIEWED 2026-06-20

How it works

1. STEP 01

   List actors

   Identify every person, system or piece of equipment that took an action during the incident window.

2. STEP 02

   Build the timeline axis

   Choose granularity (seconds, minutes) and span. Anchor with reliable timestamps from logs or CCTV.

3. STEP 03

   Place each event on its actor row

   Each action becomes a node tied to its actor and exact time.

4. STEP 04

   Draw causation links

   Connect events that influenced each other across actors using arrows.

5. STEP 05

   Highlight convergence and gaps

   Mark moments where actors collided, miscommunicated or where information was missing.