Out-of-control action plan, a flowchart attached to each SPC chart that walks the responder through the checks and actions for a violation: confirm the measurement, remeasure, check the tool log, hold or release the lot, take the tool down, escalate to engineering. A good OCAP lets the night shift resolve most OOCs in minutes without calling anyone. In fabs and automotive plants, an SPC chart without an OCAP is treated as an audit finding.
Follow the OCAP: remeasure on the backup ellipsometer first, and only call me if it's still above the UCL.
If the first box in an OCAP is not 'verify the measurement', expect a lot of tools taken down for typos and bad gauge reads.
Also heard as
- out-of-control action plan
- reaction plan
Related terms
OOC
Out of control: shorthand for a point or chart that has violated a control limit or run rule.
SPC
Statistical process control: using control charts and run rules to tell routine process noise from real changes.
Special cause
Specific, identifiable source of variation that is not part of the process's normal behavior and shows up as a chart signal.
Fat-finger
Data entry error from a mistyped number, such as a slipped decimal or swapped digits, that shows up as a false signal.