The anomaly: the raw signal

The anomaly is the broadest term. It is any observed deviation from an expected state: an out-of-tolerance value, unusual machine behaviour, or a field observation that is out of the ordinary.

The anomaly is a signal. It does not yet indicate whether the product is non-compliant or what decision to make. It simply says: something deserves a closer look.

In practice, the anomaly is often the entry point: what the operator reports, what the sensor detects, or what the engineer observes during an inspection. It is the raw material of the quality process. Its value is entirely dependent on how it is subsequently qualified.

The non-conformity: the confirmed deviation

The non-conformity is an anomaly that has been analysed and confirmed. It refers to a product, component, or process that does not meet a defined requirement: customer specification, regulatory standard, or internal standard.

It is at this stage that the quality process truly kicks in. A non-conformity must be recorded, characterised, and dealt with. It implies a decision (scrap, rework, quarantine, or acceptance under conditions) and a root cause analysis to prevent it from reoccurring.

The non-conformity is the heart of the quality system. It generates corrective action plans, CAPAs, and feedback. Properly handled, it is a source of learning. Poorly handled or ignored, it repeats itself, becomes costly, and ultimately impacts the client.

The concession: the accepted deviation

The concession (or deviation) occupies a special place. It does not refer to a defect to be corrected; it refers to a formal authorisation to accept a deviation from the requirements, under precisely defined conditions.

There are two types of deviation in industry. The deviation before production — RFD, Request for Deviation — authorises manufacturing outside standard specifications before the part is produced. The concession after production — RFW, Request for Waiver — authorises the acceptance of an already produced part that has a deviation, without reworking it or scrapping it.

In both cases, the concession is a formal act. It must be justified, documented, and approved by the parties concerned — the customer, design office, and quality manager — and accompanied by clear conditions of use. An poorly managed or insufficiently tracked concession is a major risk in an audit.

Why the distinction really matters

Confusing these three concepts means running the risk of poorly qualifying events and therefore handling them incorrectly. An anomaly not qualified as a non-conformity can slip through the cracks. A non-conformity treated as a concession without formal instruction exposes the organisation to an audit failure or a customer complaint. A concession granted without recording it in the history will have to be processed from scratch next time.

The value of a good quality system lies largely in its ability to distinguish between these three levels, to correctly qualify each event as soon as it is created, to process it according to the correct workflow, and to capitalise on every decision so as not to start from scratch.

Because quality is not managed with approximations. It is managed with clear definitions, structured processes, and an organisational memory that learns from every event.