Risk Assessment Matrix

PlaneConnection uses the standard ICAO 5x5 risk assessment matrix for evaluating safety risks. This matrix combines the severity of a hazard’s potential consequence with the likelihood of that consequence occurring to produce a risk index. The matrix is the primary tool for Safety Risk Management (SRM) under 14 CFR Part 5 Subpart C, specifically 14 CFR 5.55.

Severity Levels

Severity describes the worst credible outcome of a hazard if it were to result in an event.

Level	Category	Description	Examples
5	Catastrophic	Multiple fatalities; aircraft destroyed.	Hull loss, fatal crash, multiple fatalities.
4	Hazardous	Large reduction in safety margins; serious injury; major aircraft damage.	Substantial aircraft damage, serious injury requiring hospitalization, significant reduction in ability to cope with adverse conditions.
3	Major	Significant reduction in safety margins; injury; minor aircraft damage.	Emergency landing, minor injuries, physical distress to passengers or crew.
2	Minor	Nuisance; slight reduction in safety margins; slight injury.	Minor incident, bruises, operating limitations, use of emergency procedures.
1	Negligible	No safety effect; no injury; no damage.	Near-miss with large margin, paperwork error, minor procedural deviation with no consequence.

Likelihood Levels

Likelihood describes how often the consequence is expected to occur, based on operational experience and available data.

Level	Category	Description	Quantitative Guidance
E	Frequent	Likely to occur many times; has occurred repeatedly.	Greater than 1 in 1,000 flight hours or cycles.
D	Probable	Will occur sometimes; has occurred infrequently.	Between 1 in 1,000 and 1 in 10,000.
C	Occasional	Unlikely but possible; has occurred rarely.	Between 1 in 10,000 and 1 in 100,000.
B	Remote	Very unlikely; not known to have occurred but possible.	Between 1 in 100,000 and 1 in 1,000,000.
A	Improbable	Almost inconceivable that the event will occur.	Less than 1 in 1,000,000.

Risk Matrix

Each cell shows the risk index (likelihood + severity) and its risk zone. Rows represent likelihood (top = most frequent); columns represent severity (left = least severe).

	1 — Negligible	2 — Minor	3 — Major	4 — Hazardous	5 — Catastrophic
E — Frequent	1E — Tolerable	2E — Tolerable	3E — Unacceptable	4E — Unacceptable	5E — Unacceptable
D — Probable	1D — Acceptable	2D — Tolerable	3D — Tolerable	4D — Unacceptable	5D — Unacceptable
C — Occasional	1C — Acceptable	2C — Acceptable	3C — Tolerable	4C — Tolerable	5C — Unacceptable
B — Remote	1B — Acceptable	2B — Acceptable	3B — Acceptable	4B — Tolerable	5B — Tolerable
A — Improbable	1A — Acceptable	2A — Acceptable	3A — Acceptable	4A — Acceptable	5A — Tolerable

Risk Zones

Zone	Color	Risk Indices	Required Action
Acceptable	Green	1A, 1B, 1C, 1D, 2A, 2B, 2C, 3A, 3B, 4A	Accept the risk. Document the rationale. No additional controls required, but monitoring continues under Safety Assurance (14 CFR 5.71).
Tolerable (ALARP)	Yellow	1E, 2D, 2E, 3C, 3D, 4B, 4C, 5A, 5B	Reduce risk As Low As Reasonably Practicable. Implement controls to reduce severity, likelihood, or both. Cost-benefit analysis may be applied. Management acceptance required.
Unacceptable	Red	3E, 4D, 4E, 5C, 5D, 5E	Do not proceed without risk controls that reduce the risk to at least the Tolerable zone. Operations must be stopped or modified until controls are in place.

ALARP Principle

ALARP Principle Details

ALARP stands for As Low As Reasonably Practicable. When a risk falls in the Tolerable zone, the organization must reduce it unless the cost of further reduction is grossly disproportionate to the safety benefit gained.Demonstrating ALARP requires:

Component	Description
Identification	All reasonably practicable risk controls are identified.
Evaluation	The cost (financial, operational, practical) of each control is assessed.
Implementation	Controls are applied unless the cost is grossly disproportionate to the risk reduction achieved.
Documentation	The rationale for the final risk acceptance decision is recorded.

The burden of proof lies with the organization — it must be demonstrated that no further practicable reduction is possible, not merely that the current level is adequate.

Initial vs. Residual Risk

Every risk assessment in PlaneConnection includes two evaluations:

Assessment	Description
Initial risk	The risk level before any controls are applied. Represents the inherent risk of the hazard.
Residual risk	The risk level after controls are applied. Represents the risk the organization is accepting.

If the residual risk remains in the Unacceptable zone after all reasonably practicable controls have been considered, the operation or activity must not proceed.

Risk Assessment Fields

Field	Type	Description
`hazard`	Reference	The hazard being assessed.
`severity`	Integer (1 — 5)	Severity level of the worst credible outcome.
`likelihood`	Enum (A — E)	Likelihood of the outcome occurring.
`risk_index`	Computed	Combination of likelihood and severity (e.g., `3C`).
`risk_zone`	Computed	`acceptable`, `tolerable`, or `unacceptable`.
`initial_risk`	Object	Severity, likelihood, and risk index before controls.
`residual_risk`	Object	Severity, likelihood, and risk index after controls.
`controls`	Array	List of risk controls applied or proposed.
`effectiveness_criteria`	Text	How the organization will measure control effectiveness.
`rationale`	Text	Justification for the risk acceptance decision.
`assessed_by`	User reference	The person who performed the assessment.
`assessed_at`	Timestamp	When the assessment was performed (UTC).
`approved_by`	User reference	The person who approved the risk acceptance.
`approved_at`	Timestamp	When the risk acceptance was approved (UTC).

Regulatory Alignment

Regulation	Section	Requirement	Matrix Component
14 CFR Part 5	5.55(a)	Process to analyze safety risk	Severity and likelihood assessment
14 CFR Part 5	5.55(b)	Acceptable level of safety risk	Risk zones and acceptance criteria
14 CFR Part 5	5.55(c)	Risk controls when risk is unacceptable	Controls and residual risk evaluation
14 CFR Part 5	5.97	SMS records	Assessment records retained as long as control remains relevant
AC 120-92D	Chapter 5	SRM guidance	Matrix methodology and ALARP documentation
ICAO Doc 9859	Chapter 5	Safety Risk Management	5x5 matrix framework, severity and likelihood definitions

Conduct a Risk Assessment

Perform a risk assessment.

Risk Management Concepts

Explanation of SRM principles and philosophy.

Your First Risk Assessment

Tutorial walkthrough of the risk assessment process.

MOC Workflow

How risk assessment integrates with Management of Change.

SMS Reference

SmartScore

Operations Reference

FBO Reference

Maintenance Reference

Operational Reports

Portal Reference

Platform Reference

API Reference

Severity Levels

Likelihood Levels

Risk Matrix

Risk Zones

ALARP Principle

Initial vs. Residual Risk

Risk Assessment Fields

Regulatory Alignment

Conduct a Risk Assessment

Risk Management Concepts

Your First Risk Assessment

MOC Workflow

​Severity Levels

​Likelihood Levels

​Risk Matrix

​Risk Zones

​ALARP Principle

​Initial vs. Residual Risk

​Risk Assessment Fields

​Regulatory Alignment

​Related

Conduct a Risk Assessment

Risk Management Concepts

Your First Risk Assessment

MOC Workflow

Severity Levels

Likelihood Levels

Risk Matrix

Risk Zones

ALARP Principle

Initial vs. Residual Risk

Risk Assessment Fields

Regulatory Alignment

Related