Aircraft Accident vs. Incident: Thresholds, Reporting, and Investigation

The difference between an aircraft accident and an incident comes down to severity, and federal regulations draw the line in specific terms. An aircraft accident is an event tied to flight operations in which someone dies, someone suffers a serious injury, or the aircraft sustains substantial damage. An incident is any other occurrence that affects or could affect safe operation but falls below those thresholds. The label matters because it drives how fast you must notify the NTSB, whether you owe a written report, and whether investigators show up at the scene.

What Makes an Event an Accident

Under 49 CFR 830.2, an accident is an occurrence associated with the operation of an aircraft that takes place between the time any person boards with the intention of flight and the time all such persons have disembarked, and in which anyone suffers death or serious injury or the aircraft receives substantial damage.¹ Three triggers, one time window. If any trigger fires during that window, the event is legally an accident no matter how routine the flight looked otherwise.

Fatal Injury: The 30-Day Rule

A fatal injury is one that results in death within 30 days of the event. Day 31 is a bright line. If the person dies later, the injury does not count as fatal for classification, though the event can still be an accident if the injury cleared the serious-injury bar.¹

Serious Injury: Broader Than People Expect

A serious injury is any of the following:¹

Hospitalization for more than 48 hours, beginning within seven days of the injury
Any bone fracture other than a simple fracture of a finger, toe, or the nose
Severe hemorrhages or damage to nerves, muscles, or tendons
Any internal organ injury
Second- or third-degree burns, or burns covering more than 5 percent of the body

The burns and hemorrhage prongs are the ones commonly missed. A passenger with significant burns from an in-flight fire can push an event into accident territory even if no bones are broken and no one is admitted to a hospital.

Substantial Damage: What Doesn’t Count

Substantial damage is damage that adversely affects the aircraft’s structural strength, performance, or flight characteristics and that normally requires major repair or replacement of the affected component. The regulation then carves out a long list of damage that does not qualify: dented skin, bent fairings or cowlings, small holes in skin or fabric, ground damage to propeller or rotor blades, and damage limited to the landing gear, wheels, tires, flaps, brakes, wingtips, or a single engine.¹

The classification looks at what was damaged, not the repair invoice. A hard landing that shreds the gear and blows a tire but leaves the fuselage and wings structurally sound is not an accident, even if the airplane is grounded for weeks of expensive work.

What Counts as an Incident

An incident is any occurrence, other than an accident, associated with aircraft operations that affects or could affect the safety of operations.² The definition is intentionally broad. A misfiring warning light in cruise, a bird strike that cracks a windshield without structural compromise, an unauthorized runway crossing that never results in contact: all incidents.

Not every incident requires reporting. The regulation picks out a specific set of serious incidents that must be notified to the NTSB with the same urgency as an accident. These are the near-miss category, where something went meaningfully wrong even though no one was seriously hurt and the aircraft escaped substantial damage.

Serious Incidents That Require Immediate Notification

The following events must be reported immediately, by the fastest means available:³

Flight control system malfunction or failure
Any required flight crewmember unable to perform normal duties because of injury or illness
Turbine engine failure in which debris exits somewhere other than the exhaust path
In-flight fire
Mid-air collision that does not meet the accident threshold
Damage to ground property (other than the aircraft) that exceeds $25,000 for repair or fair market value, whichever is less
Propeller blade release in flight, not caused solely by ground contact
Loss of information from more than half the cockpit displays
Airborne collision-avoidance system alerts that required compliance on an IFR flight to avert a near-collision
Helicopter main or tail rotor blade damage, including ground damage, requiring major repair or replacement
Air carrier landing or takeoff on the wrong runway, a taxiway, or a closed or non-runway surface at a public airport, or a runway incursion requiring immediate evasive action

Aircraft with a certificated maximum gross takeoff weight over 12,500 pounds have additional triggers: in-flight electrical failure requiring the sustained use of an emergency bus, hydraulic failure leaving only one system to move the flight controls, loss of thrust or power from two or more engines, and any evacuation using an emergency egress system.³

What Each Classification Requires You to Do

For accidents and for the serious incidents listed above, the first step is the same: notify the nearest NTSB field office immediately, by the fastest means available. In practice that means a phone call, though remote operations may need satellite or radio relay.

The notification should include, to the extent available, the aircraft type and registration number, the operator and pilot-in-command names, the date and time of the event, the point of departure and intended destination, the last known position relative to a recognizable landmark, the number of people aboard along with the number killed or seriously injured, a description of what happened and the weather, the extent of damage as it is known, and whether any explosives, radioactive materials, or other hazardous cargo was aboard.²

The Written Report Deadlines Diverge

This is where the accident and incident tracks split. After an accident, the operator must file a written report on NTSB Form 6120 within 10 days. For an overdue aircraft still missing after seven days, the same form is due at that point. After a serious incident, no written report is due automatically; the operator files one only if the NTSB requests it.⁴

Treating every notifiable event as if a written report will be required is the cautious approach, but the legal deadline exists only for accidents.

Wreckage Preservation

When an event triggers mandatory notification, the operator must preserve the wreckage, cargo, mail, and all records including cockpit voice and flight data recorders. Nothing can be moved or disturbed until the NTSB takes custody or grants a release, with three exceptions: removing injured or trapped persons, protecting the wreckage from further damage, and protecting the public from injury.⁵ Moving anything outside those exceptions risks the investigation and invites enforcement. When in doubt, document with photos and leave the scene alone.

How Investigations Differ

Every civil aircraft accident is investigated by the NTSB, which has exclusive authority over the probable cause determination. For complex cases the NTSB deploys a Go-Team of specialists tailored to the event. For less complex general aviation accidents, the NTSB may have FAA inspectors do the on-scene fact gathering, but the investigation still belongs to the NTSB and the FAA inspector acts under NTSB authority.⁶

Incidents are investigated selectively. The NTSB may open a targeted investigation focused on a specific safety concern, or it may simply log the notification data for trend analysis. A Go-Team is not deploying for an incident. Classification is not necessarily permanent, though: if later evidence shows that injuries or damage cleared the higher threshold, the NTSB can upgrade an incident to an accident.⁷

Drone Operations Follow Different Rules

Unmanned aircraft have their own accident definition, and it is narrower than the manned-aircraft version. A drone event is an accident only if someone on the ground dies or suffers a serious injury under the same thresholds above, or if the drone itself carries an airworthiness certificate and sustains substantial damage. Most Part 107 drones do not carry airworthiness certificates, so destroying the aircraft in a crash is not an “accident” under NTSB rules unless a person was hurt.²

Separately, Part 107 operators owe the FAA a report when the drone damages property other than the drone itself and the repair cost or fair market value exceeds $500. That is far lower than the $25,000 property-damage threshold for manned aircraft. A drone that clips a car windshield requiring a $600 replacement is a reportable event even though no one was hurt and the drone flew home fine.⁸

Downstream Consequences of the Label

The classification reaches beyond the notification phone call. Federal law bars any part of an NTSB accident report from being admitted as evidence or used in a civil action for damages arising from the events the report covers.⁹ Because incidents typically produce far less formal reporting, civil cases tied to incidents tend to rely more on FAA records, maintenance logs, and independent expert work than on any NTSB conclusion.

The FAA runs its own track in parallel. The NTSB investigates to prevent recurrence; the FAA investigates to decide whether anyone violated the regulations, and the two can proceed simultaneously. After an accident, FAA inspectors may pull pilot records, maintenance documentation, and operational compliance data on their own, and the agency can pursue certificate action including suspension or revocation. The regulations explicitly preserve that authority during an ongoing NTSB investigation.⁶ Incidents can produce FAA enforcement too, but the lower investigative profile means fewer eyes on the event by default.

1
eCFR. 49 CFR 830.2 – Definitions
2
eCFR. 49 CFR Part 830
3
eCFR. 49 CFR 830.5 – Immediate Notification
4
eCFR. 49 CFR Part 830 Subpart D
5
eCFR. 49 CFR 830.10 – Preservation of Aircraft Wreckage, Mail, Cargo, and Records
6
eCFR. 49 CFR 831.21 – Other Government Agencies and NTSB Aviation Investigations
7
NTSB. Aviation Investigation Classification
8
eCFR. 14 CFR 107.9 – Safety Event Reporting
9
Office of the Law Revision Counsel. 49 USC 1154