AFR / IFR & Safety Metrics Overview

1. Frequency Metrics

Core Metrics

AFR – Accident Frequency Rate

Measures reportable injuries relative to total hours worked.

Formula:
AFR = (RIDDOR-reportable injuries × 100,000) / Total hours worked

Standard:
UK Health and Safety Executive (HSE)

IFR / TRIFR – Incident / Total Recordable Injury Frequency Rate

Measures all recordable incidents relative to total hours worked.

Formula:
IFR = (Recordable incidents × 200,000) / Total hours worked

Standard:
OSHA (USA)

Other Configurable Metrics

LTIFR – Lost Time Injury Frequency Rate

Measures injuries that impact productivity (time lost).

Includes:

• Lost Time Injuries (LTI)
• Fractures requiring time off
• Serious sprains/strains
• Surgical cases

Excludes:

• First Aid cases
• Medical Treatment cases with immediate return
• Near misses

Formula:
LTIFR = (Lost Time Injuries × Multiplier) / Total hours worked

AIFR – All Injury Frequency Rate

Captures all injuries across the severity spectrum, providing the most complete picture of injury frequency.

Includes:

• LTI, MTI, RWC
• Minor injuries (e.g. stitches)
• Restricted work cases

Excludes:

• Near misses (no injury)
• Hazard observations

Formula:
AIFR = (All injuries × Multiplier) / Total hours worked

SIFR – Serious Injury Frequency Rate

Measures high severity incidents (life-changing or fatal risks).

Includes:

• Fatalities
• Permanent disabilities
• Major fractures
• Serious head injuries

Excludes:

• Minor injuries
• First Aid
• Low-risk medical cases

Formula:
SIFR = (Serious injuries × Multiplier) / Total hours worked

2. Supporting Indicators

SIFp – Serious Injury / Fatality Potential

Identifies incidents that had the potential to result in serious harm or fatality, even if the outcome was minor.

SSR – Safety Observation / Reporting

Represents proactive safety reporting activities such as observations, hazard reports, and improvements.

HIPO – High Potential Incident

An incident that could have resulted in serious injury or fatality under slightly different circumstances.

3. Onos Calculation Logic

The system can use either:

• Actual recorded monthly hours or
• A calculated method based on configured working assumptions by number of people

Note: This behaviour can be configured or hidden as required.

Calculated Method

Frequency Rate:
Frequency Rate = (Incidents / Hours) × Multiplier

Monthly Hours Calculation:
Monthly Hours = Users x Avg. weeks in month × Avg. hours in day × Avg. days in week × optional uplift

Example:
Hours = 4.0833 × 9 × 5 × 1.05

4. Data Sources

• Workforce hours (employees, subcontractors, visitors)
• Incident records

5. Dashboard Overview

The AFR / IFR dashboard includes:

• AFR / IFR summary cards (Actual vs Target)
• Trend charts (e.g. rolling 12 months)
• Safety Pyramid (incident distribution by severity)
• Incident breakdown by type

6. Configuration

Default

• AFR = 100,000 multiplier
• IFR = 200,000 multiplier

Custom

• Adjustable multipliers
• Working hours configuration
• Workforce inclusion rules
• Optional uplift factor

7. Metrics Summary Table

Core Metrics

Key Metrics (Next Most Important)

Supporting Metrics

Updated on: 02/04/2026