A mishap resulting in one or more of the following:
- Direct mishap cost totaling $2,500,000 or more.
- A fatality or permanent total disability.
- Destruction of a Department of Defense aircraft.
- Permanent loss of primary mission capability of a space vehicle.

A mishap resulting in one or more of the following:
- Direct mishap cost totaling $600,000 or more but less than $2,500,000.
- A permanent partial disability.
- Inpatient hospitalization of three or more personnel (not counting individuals hospitalized for observation, diagnostic, or administrative purposes that were treated and released.
- Permanent degradation of primary or secondary mission capability of a space vehicle or the permanent loss of secondary mission capability of a space vehicle.

A mishap resulting in one or more of the following:
- Direct mishap cost totaling $60,000 or more but less than $600,000.
- Any injury or occupational illness that causes loss of one or more days away from work not including the day or shift it occurred.
- An occupational injury or illness resulting in permanent change of job.
- Permanent loss or degradation of tertiary mission capability of a space vehicle.

A mishap resulting in one or more of the following:
- Direct mishap cost totaling $25,000 or more but less than $60,000.
- Any mishap resulting in a recordable injury or illness not otherwise classified as a Class A, B, or C mishap. These are cases where, because of injury or occupational illness, the employee only works partial days, has restricted duties (does not include medical restriction from flying or special operational duties (DNIF) or was transferred to another job, required medical treatment greater than first aid, or experienced loss of consciousness.  In addition, a significant injury (e.g. fractured/cracked bone, punctured eardrum) or occupational illness (e.g. occupational cancer (mesothelioma), chronic irreversible disease (beryllium disease) diagnosed by a physician or other licensed health care professional must be reported even if it does not result in death, days away from work, restricted work, job transfer, medical treatment greater than first aid, or loss of consciousness.

- An event cost totaling < $25K. Certain occurrences do not meet reportable mishap classification criteria, but are deemed important to investigate/report for hazard identification and mishap prevention. Class E reports provide an expeditious way to disseminate valuable mishap prevention information.

A real or potential condition that could lead to an unplanned event or series of events (i.e., mishap) resulting in death, injury, occupational illness, damage to or loss of equipment or property, or damage to the environment. Hazards have no associated damage or injury but are important to identify.