SIMOPS Must Be Managed as One Combined Risk

The interaction may be the real hazard

Simultaneous operations, commonly called SIMOPS, occur when two or more activities take place at the same time or in connected areas and one can affect the safety of another. Offshore examples can include production beside maintenance, lifting over or near operating equipment, testing alongside live operations, marine activity near the installation, or several permitted jobs drawing on the same people, utilities or escape routes.

Each activity may have a valid risk assessment and permit, yet the combined situation can introduce a hazard that is not obvious when the jobs are reviewed separately. One task may alter containment, ventilation, ignition control, access, communications, staffing, process stability or emergency response for another. Safe SIMOPS therefore depends on understanding interfaces, not merely counting permits.

A permit controls a job—not the whole operating picture

UK HSE describes a permit to work as a formal system that states what work is to be done, when it will occur and which parts are safe. HSE also stresses that issuing a permit does not by itself make a job safe and that a permit does not replace robust risk assessment. Its value includes communication and coordination between management, plant supervisors, operators and the people carrying out the work.

For multiple permits, HSE advises making links between related permits and considering simultaneous tasks and interdependent activities. That principle is crucial offshore. An authorised hot-work permit does not show, by itself, whether a nearby drain will be opened later, whether a crane lift may restrict access, or whether another intervention will temporarily change the gas-detection or shutdown arrangement. Those interfaces need deliberate review at the level that can see the complete plan.

Hypothetical example: work scopes that become incompatible

Consider a hypothetical FPSO where scaffolders are working near a process module while a maintenance team prepares to open a drained hydrocarbon pump under an approved isolation. Elsewhere, a planned crane lift will temporarily restrict one access route. Each activity has been assessed and authorised separately.

This is an illustrative scenario, not a documented incident. During the shift, the pump team identifies a need to extend its boundary and open an additional connection. At the same time, changing wind direction could affect where any residual vapour travels, while the lift changes movement and emergency-access arrangements. The original combination of controls may no longer represent the work now being done.

The disciplined response is to hold the affected activities at an approved safe point, bring the responsible operations and work-control personnel together, reassess the interfaces and follow the site's authorised change and escalation process. The important question is not whether each individual permit remains signed; it is whether the combined operation remains inside the approved risk envelope.

Build one shared operating picture

A useful SIMOPS review identifies where activities overlap in location, time, equipment, energy sources, utilities, safeguards, people and emergency arrangements. It should make dependencies visible: which isolation protects more than one job, which work can introduce an ignition source, who controls a shared valve or electrical supply, whether a lift passes near live plant, and whether access, muster or evacuation routes remain available.

The control room, area authority, performing authorities and relevant specialists must work from the same current picture. HSE notes that safety-critical communication matters when coordinating activities between different parties and organisations. It recommends identifying who needs to communicate, selecting suitable written or verbal methods, communicating before people begin the task, and highlighting safety-critical steps. Where a message is critical, more than one communication method may be appropriate under site procedures.

Define precedence, ownership and stop triggers

SIMOPS control becomes fragile when responsibility is distributed but no one owns the overall interface. The approved plan should identify who coordinates the combined work, who may authorise changes, which activity takes priority if conditions conflict and who has authority to suspend one or more jobs. People conducting the work should understand these arrangements before starting—not discover them during a developing problem.

Stop or reassessment triggers should be specific enough to act on. Examples may include a gas alarm, loss of communication, changing weather, an unexpected process condition, a degraded barrier, a lift moving outside its approved envelope, loss of access, or any change to job scope. The applicable triggers are installation- and task-specific; they must come from approved risk assessments, permits and procedures. If a condition falls outside that basis, pause and escalate rather than improvising a new arrangement in the field.

Manage change throughout the execution window

A SIMOPS plan is only valid for the conditions assessed. Work can drift as schedules move, teams rotate, equipment becomes unavailable or a seemingly small scope extension is proposed. Refresh the shared picture at shift handover and at specified coordination points. Confirm which jobs are active, suspended or complete; which isolations and overrides remain; what has changed; and which interactions will arise next.

Completion also changes the risk picture. Reinstating equipment, removing isolations, energising a system or clearing a worksite can affect another ongoing task. HSE advises that permit systems include handover of plant when work is complete. Coordinate reinstatement through the approved process and verify that connected permits, people and plant are ready before changing the configuration.

Three practical actions for today's shift

First, review today's work as a combined map—not as separate permits—and identify interfaces in location, timing, energy, safeguards, access and emergency response. Second, confirm one accountable coordinator, clear activity precedence and explicit stop or reassessment triggers, in line with site procedures. Third, require a fresh interface review whenever the scope, plant condition, weather, barrier status or timing changes; ensure the result is communicated to every affected team.

Discussion question: Which two activities planned today could be safe individually but become incompatible if their timing, boundary or plant condition changes—and who is watching that interface?

This article provides general process-safety learning. SIMOPS planning, permit control, risk assessment, authorisation, communication and escalation must follow the installation's approved procedures and competent direction.