Critical Operational Issues (COI) are the operational effectiveness and operational suitability issues (not parameters, objectives, or thresholds) that must be examined to evaluate/assess the system’s capability to perform its mission. Not all operational issues are critical. COIs must be relevant to the required capabilities for a system to be operationally effective and suitable and represent a significant risk if not satisfactorily resolved. 
COIs must be examined and related to Measures of Effectiveness (MOE) and Measures of Suitability (MOS), and are included in the Test and Evaluation Master Plan (TEMP).
- Measure of Effectiveness (MOE)
- Measure of Performance (MOP)
- Measure of Suitability (MOS)
- Test and Evaluation Master Plan (TEMP)
A COI is normally phrased as a question that must be answered in the affirmative to properly evaluate operational effectiveness. The following are four examples of critical operational issues statements in the TEMP: 
- Will the platform/system (or subsystem/equipment) detect the threat in a combat environment at adequate range to allow a successful mission?
- Will the system be safe to operate in a combat environment?
- Can the platform/system (or subsystem/equipment) accomplish its critical missions?
- Is the platform/system (or subsystem/equipment) ready for Joint and, if applicable, Combined operations?
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