Summary
In short
- The reaction plan column is the working part of the plan. Without a defined action, an out-of-specification result produces a judgement made under production pressure by whoever is present.
- IATF 16949 requires control plans at three phases, prototype, pre-launch and production, and requires review after change, after nonconformance and when the process is unstable or not capable.
- Characteristics should trace to the FMEA. Where they do not, the plan is documenting current inspection practice rather than implementing a risk analysis.
- Sample size and frequency need a rationale. A plan specifying five pieces per hour with no basis is a guess that will be defended as a standard.
- The measurement method must be capable for the tolerance it checks, which is why gauge R&R belongs behind the control plan rather than alongside it.
- A control plan that does not match what operators actually do is worse than none, because it represents a documented commitment that is being breached every shift.
What it is
What it is
What is a control plan?
A control plan is a documented description of the systems used to control a product or process. For each process step it lists the product and process characteristics, the specification or tolerance, the evaluation method, the sample size and frequency, the control method, and the reaction plan when the characteristic falls outside specification.
How does a control plan relate to the FMEA?
The FMEA identifies failure modes, their effects and their causes, and assesses risk. The control plan implements the controls the FMEA identified as necessary. They are a linked pair: a control plan whose contents cannot be traced to an FMEA has controls chosen for reasons nobody recorded, and an FMEA with no corresponding controls is analysis without action.
When to use it
When to use it, and when not to
The control plan sits between the FMEA and the work instruction, and takes on their jobs only at the cost of doing its own badly.
Use it for
- A new product or process is being introduced and requires prototype, pre-launch and production control plans
- An existing process has changed in method, equipment, material or supplier
- A nonconformance or customer complaint indicates the current controls did not detect the condition
- Process capability studies show the process is not stable or not capable
- A customer requires a control plan as part of PPAP or an equivalent approval submission
Not for
- The FMEA itself, which identifies and ranks failure modes and should precede the control plan rather than being replaced by it
- The work instruction, which tells the operator how to perform the task; the control plan tells them what is checked and what to do when it fails
- Gauge R&R and measurement system analysis, which sit behind the plan and determine whether its methods are capable
- The inspection record itself, which is the evidence generated by following the plan
- Process flow diagrams, which establish the sequence the control plan then annotates
Standards
What it is built against
Control plans are required by automotive quality standards and used well beyond them. The requirements concern completeness, traceability to risk analysis, and review triggers.
| Clause | Requirement | Where it lands |
|---|---|---|
| IATF 16949 cl.8.5.1.1 | Control plans developed at system, subsystem, component or material level for prototype, pre-launch and production | Plan header and phase |
| IATF 16949 cl.8.5.1.1 | Review and update after change to product, process, measurement, logistics, supply source or FMEA | Revision control |
| IATF 16949 cl.9.1.1.1 | Statistical tools determined during advanced quality planning and included in the control plan | Control method |
| IATF 16949 cl.8.5.1.1 | Reaction plans specified when nonconforming product or process instability is detected | Reaction plan |
| ISO 9001 cl.8.5.1 | Controlled conditions including availability of documented information defining characteristics and results | Whole record |
| AIAG APQP | Control plan derived from process flow and FMEA as part of advanced product quality planning | Characteristic derivation |
| ISO 9001 cl.7.1.5 | Monitoring and measuring resources suitable and verified for the measurement being made | Evaluation method |
| ISO 9001 cl.8.7 | Control of nonconforming outputs, including identification and action | Reaction plan |
What it does not cover
- The FMEA, which identifies the failure modes the control plan responds to and must exist first.
- Work instructions, which describe how the operation is performed rather than what is monitored.
- Measurement system analysis, which establishes whether the specified evaluation method is capable.
- Process capability studies, which are performed on a stable process and inform whether the control plan is adequate.
- Inspection and test records, which are the output of following the plan, not the plan itself.
Filling it in
Filling it in well
A control plan is filled in column by column and lives or dies on two of them: the basis for sample frequency and the content of the reaction plan.
The characteristics in the plan should be those the risk analysis identified as needing control, including special characteristics designated by the customer or by design. A plan assembled by documenting what is currently inspected reproduces existing practice and its blind spots, which is exactly what the FMEA was supposed to correct.
Whatever the plan specifies will become the standard and will be defended as such long after anyone remembers why. Recording the basis, whether statistical, historical, customer-specified or a conservative judgement, means the frequency can be revised on evidence rather than argued about from memory.
The reaction plan is executed by whoever is present when the result comes back out of specification, frequently at 3am. It should name what to contain and how far back, who to notify, who decides disposition, and whether production stops. Specificity here is the difference between a control and a documented intention.
Walk the process against the plan periodically. Where the operator checks something the plan does not mention, or does not check something it requires, one of the two is wrong. A mismatch is a finding either way, and it is the single most common thing an auditor finds by walking the line with the plan in hand.
Audit findings
Common audit findings
Control plan findings cluster around traceability to the FMEA, the reaction plan column, and whether the plan matches the floor.
| Finding | Clause | What fixes it |
|---|---|---|
| Control plan does not match observed practice at the process. | IATF 16949 cl.8.5.1.1 | Walk the process against the plan; correct whichever is wrong and record why. |
| Reaction plan absent or non-specific, offering no containment boundary or decision authority. | IATF 16949 cl.8.5.1.1 | Specify containment scope, notification, disposition authority and whether to stop. |
| Characteristics not traceable to the FMEA, or FMEA updated without the plan following. | AIAG APQP | Link plan revisions to FMEA revisions so one cannot change without prompting the other. |
| Special characteristics not identified or not flowed down to suppliers. | IATF 16949 cl.8.3.3.3 | Designate special characteristics explicitly and include them in supplier requirements. |
| Measurement method specified is not capable for the tolerance being checked. | ISO 9001 cl.7.1.5 | Perform gauge R&R before the method is fixed in the plan, not after a dispute. |
| Sample size and frequency without documented rationale. | IATF 16949 cl.9.1.1.1 | Record the basis at the point of decision; it will be needed at the first review. |
| Plan not reviewed after a process, material or supplier change. | IATF 16949 cl.8.5.1.1 | Add control plan review to the change control checklist as a required step. |
| Pre-launch controls carried into production unchanged despite reduced risk. | IATF 16949 cl.8.5.1.1 | Review at phase transition; pre-launch intensity is deliberate and temporary. |
| Out-of-specification results recorded with no evidence the reaction plan was followed. | ISO 9001 cl.8.7 | Require the reaction plan reference on the nonconformance record. |
| Revision control weak, with multiple versions in circulation at the process. | ISO 9001 cl.7.5.3 | Control at the point of use; the version in the operator's hand is the one that matters. |
Worked case
Case in point: the plan that was followed exactly
A supplier producing machined components had a mature control plan. Key characteristics were listed, tolerances were correct, gauges were calibrated, and the sampling frequency was met every shift. An audit found no deviation from the plan.
The customer nonetheless received a batch outside tolerance. The investigation found the reaction plan for that characteristic read "quarantine and inform quality". On the night in question the operator quarantined the piece, informed quality by leaving a note, and continued running because nothing told them to stop. Four hours of production went into the customer's stock before the note was read.
Every element of the plan had been followed. The reaction plan simply did not answer the question that mattered, which was how far back to contain and whether to keep running.
Definitions
Definitions and key terms
- Special characteristic
- A product or process characteristic affecting safety, regulatory compliance, fit, function or subsequent processing, designated by customer or design and requiring specific control.
- Reaction plan
- The defined action when a characteristic falls outside specification, covering containment, notification, disposition authority and whether production continues.
- Control method
- How the characteristic is controlled: statistical process control, mistake proofing, one hundred percent inspection or an automated check.
- Prototype control plan
- Controls applied during prototype build, typically with higher inspection intensity than production.
- Pre-launch control plan
- Enhanced controls applied after prototype and before full production, deliberately more intensive and deliberately temporary.
- Process flow diagram
- The sequence of operations the control plan annotates, including inspection points and rework loops.
- Mistake proofing
- A control preventing the error occurring or preventing defective product passing, which is more reliable than detection by inspection.
- PPAP
- Production part approval process, the submission package demonstrating a supplier can produce to requirement, in which the control plan is a required element.
FAQ
Frequently asked questions
What makes a reaction plan adequate?+
That it answers, without further consultation, what to contain and how far back, who to notify, who decides disposition and whether to keep running. A reaction plan reading "investigate" or "inform quality" leaves the operational decision to the person least placed to make it, at the moment they are under most pressure.
How does the control plan relate to the FMEA?+
The FMEA identifies and ranks failure modes and determines what needs controlling; the control plan implements those controls. They should be revised together, because an FMEA update that does not reach the control plan means the analysis has changed and the practice has not, which is a common finding and a genuine exposure.
When must a control plan be reviewed?+
After any change to product, process, measurement method, logistics, supply source or FMEA, after a nonconformance, and when the process proves unstable or not capable. IATF 16949 lists these explicitly. In practice the change-driven triggers are missed most often, because control plan review is not on the change control checklist.
Do the three phases need separate plans?+
Yes, and they should genuinely differ. Prototype and pre-launch plans carry deliberately higher inspection intensity because process capability is not yet demonstrated. Carrying pre-launch intensity into production wastes inspection effort; carrying production intensity into pre-launch misses the problems the phase exists to find.
Is a control plan only for automotive?+
It originates in automotive quality planning and is required by IATF 16949, but the structure suits any manufacturing operation. Food, pharmaceutical and general manufacturing all benefit from a single document stating what is monitored, how, how often and what happens when it fails, whatever it is called locally.
The agents
What the agents do with it
The plan is a table. What fails is its currency against the FMEA, its match with the floor, and whether the reaction plan is followed when it is needed.
Holds the control plan against the FMEA and process flow, flags characteristics that changed in one and not the other, and controls revision at the point of use.
Watches nonconformances for whether the reaction plan was referenced and followed, and surfaces characteristics that fail repeatedly despite being in control.
Connects equipment changes and maintenance to the control plan, since a machine change can invalidate a control method.
Ties control plan revisions to operator training, so a changed reaction plan reaches the people who execute it.
This template lives in KnowQuality — quality and food safety. HACCP, nonconformance, traceability, laboratory and customer complaints.
Sources
Sources
- IATF 16949:2016 clauses 8.5.1.1, 8.3.3.3 and 9.1.1.1
- AIAG Advanced Product Quality Planning and Control Plan reference manual
- AIAG Potential Failure Mode and Effects Analysis reference manual
- AIAG Measurement Systems Analysis reference manual
- ISO 9001:2015 clauses 8.5.1, 7.1.5 and 8.7