Aviation Safety Glossary

An airworthy aircraft, under the crew's control, is flown into ground, water or an obstacle — usually because nobody on the flight deck knew the terrain was there.

The aircraft departs from normal controlled flight — a stall, an upset, or a control problem the crew cannot recover from.

A crew action or omission was a causal factor. Modern investigators treat it as a starting point, not a verdict — the useful question is why the action made sense at the time.

Crew Resource Management: how a flight deck uses all the people and information available to it. CRM breakdowns are about communication, workload and authority, not stick-and-rudder skill.

An engineering or maintenance action — a part fitted wrongly, an inspection missed, a repair done off-manual — contributed to the accident.

Decisions and pressures outside the flight deck — dispatch, loading, scheduling, air traffic services, company culture — that shaped the outcome.

Two aircraft collide in flight. Investigations centre on separation: who was responsible for it, what each crew could see, and what the collision-avoidance systems did.

A component or system failed in service. The investigation asks why the part failed and why the failure was not contained by design, inspection or redundancy.

The airframe itself broke — commonly through fatigue cracking, corrosion, an improper repair, or loads beyond what the structure could take.

Loss of thrust from one or more engines. Whether it becomes an accident usually depends on when it happened and what the crew did next.

The aircraft told the crew something untrue — blocked pitot tubes, a failed angle-of-attack vane, disagreeing airspeed or altitude indications.

Windshear, thunderstorms, turbulence, icing or low visibility were causal. The finding is usually less about the weather than about the decision to fly into it.

A collision with birds, most often during takeoff or approach, and most dangerous when it takes out more than one engine.

Fire or smoke aboard in flight. It is time-critical: historically, crews have had well under half an hour from the first smell of smoke.

Deliberate unlawful interference — a bomb, a hijacking, or an act by someone aboard. The investigation is criminal as well as technical.

A civil aircraft was hit by military weapons or damaged in an armed conflict, including misidentification by air defences.

No cause has been established yet. Anything published before the final report is provisional, including the widely repeated early theories.

The investigating authority has published its concluding report, with findings, causes and safety recommendations. This is the authoritative account.

A preliminary or interim publication. It states facts established so far and normally contains no conclusion about cause.

The investigation is open and nothing conclusive has been published. Expect a final report in one to three years, sometimes longer.

No report state could be established — usually an older occurrence whose documentation is not publicly available, or one where no formal investigation was published.

From the start of the takeoff roll to a few hundred feet above the runway — statistically one of the two most dangerous parts of a flight.

From just after liftoff to the cruise level. High thrust, high workload, close to the ground for the first part of it.

Level flight between climb and descent. The longest phase and the one with the fewest accidents per hour.

From leaving cruise level to joining the approach. Workload rises as the aircraft is slowed, configured and briefed.

From joining the approach to just before touchdown. Together with landing it accounts for a disproportionate share of accidents relative to time spent.

Flare, touchdown and rollout. Overruns, hard landings, runway excursions and loss of directional control live here.

Manoeuvring on the ground under the aircraft's own power. The phase where runway incursions happen.

Stationary operations: parking, boarding, servicing, refuelling and maintenance.

The international standard governing aircraft accident investigation. It defines who investigates, what an accident is, and that the sole objective is prevention — not blame.

The authority's formal statement of what caused the accident. The exact wording matters, and the archive quotes it rather than paraphrasing it.

A formal proposal from the investigators to a regulator or operator. Recommendations are not binding — the regulator decides what to mandate.

A legally binding instruction from a regulator requiring an inspection, repair or modification on a type. Unlike a recommendation, compliance is mandatory.

An accident involves death, serious injury, substantial damage or a missing aircraft. Anything else affecting safety is an incident — a serious incident being one that nearly became an accident.

The crash-protected recorder that captures aircraft parameters — attitude, speeds, control positions, systems states — for at least the last 25 hours.

The recorder capturing flight-deck audio — crew speech, radio calls, alerts and ambient sound. Its contents are legally protected.

Terrain awareness and warning systems. They compare the aircraft's position against a terrain database and call "terrain, pull up" before impact.

Airborne collision avoidance. It interrogates nearby transponders and, if a collision is likely, issues a coordinated climb or descend instruction to both crews.

How much life the airframe has used. Hours measure time in service; a cycle is one takeoff and landing, and it is cycles that drive fatigue.