Fires and smoke in the passenger compartment, in cargo compartments or engine fires, even though such fires were extinguished by the use of extinguishing agents. Events requiring the emergency use of oxygen by the flight crew. Aircraft structural failures or engine disintegrations not classified as an accident.

In aviation, an "incident" is defined as an occurrence, other than an accident, which affects or could affect the safety of operations. A classic example of an aviation incident is a "runway incursion," where an aircraft, vehicle, or person is incorrectly on the runway, forcing a departing or landing plane to take evasive action, such as a "go-around." Another common example is a "bird strike" that causes minor damage to the airframe or a single engine, but allows the plane to land safely. Technical failures that do not result in injury or major structural damage, such as the failure of one of two hydraulic systems or a "flamed out" engine that is successfully restarted or managed with the remaining engine, are also classified as incidents. For instance, if a plane suffers a landing gear malfunction that requires an emergency landing but everyone walks away unharmed and the plane is repairable, it is an incident. The key distinction is that while an accident involves serious injury or "substantial damage" (structural failure), an incident is a "close call" or a technical hiccup that serves as a vital learning tool for safety investigators to prevent future tragedies.