Fatigue Risk Management for Part 135: Beyond Duty Time Tracking

Part 135 prescriptive duty time rules (10-hour rest, 500 hours per quarter, 34 hours per 7 days) set minimum legal thresholds. But fatigue is biological — a pilot can be fully compliant with duty limits and still be dangerously fatigued due to circadian disruption, sleep debt, or early report times.

FRMS addresses the gap between legal compliance and actual fatigue risk. This is increasingly important as the FAA moves toward performance-based regulation through SMS.

An FRMS includes: fatigue risk identification (scheduling analysis, crew surveys, incident data), fatigue risk assessment (bio-mathematical modeling, operational context), fatigue mitigation (controlled rest, strategic scheduling, nap policies), and fatigue monitoring (ongoing data collection and trend analysis).

The FAA's AC 120-103A provides the framework. For Part 135 operators, the practical challenge is building these components without airline-scale resources.

Sleep opportunity analysis: review each crew member's schedule for the previous 72 hours before each duty period. If cumulative sleep opportunity falls below 5 hours in any 24-hour window, that is a high-risk assignment.

Karolinska Sleepiness Scale (KSS): a simple 1-9 self-report scale that crew members complete before flights. Scores of 7 or higher indicate significant sleepiness and should trigger mitigation.

Scheduling buffers: build rest margins beyond minimums. A 12-hour rest period that includes a hotel commute and meal time may yield only 6 hours of actual sleep opportunity.

FRMS data is some of the highest-value input for your SMS. Fatigue reports, KSS trends, and scheduling risk assessments feed directly into Safety Risk Management and Safety Assurance activities.

Track fatigue-related safety reports as compliance tasks in Navlyt Compliance and link them to corrective actions through your SMS audit trail.