Does this tool determine fitness for flight?

No. This estimator is a self-assessment aid only and does not determine medical fitness, legal fitness, or operational readiness.

Why do pilots assess fatigue?

Pilots assess fatigue because reduced sleep, long duty periods, circadian disruption, and stress can affect alertness, decision making, and performance.

Should this be used instead of IMSAFE or official guidance?

No. This tool is a supplement for personal awareness. Pilots should still use IMSAFE, official guidance, and sound judgment.

Aviation Training Experts

Fatigue Estimator

Q: What is a fatigue estimator?

A fatigue estimator is a self-assessment planning tool that uses factors such as sleep, time awake, duty length, and stress to estimate relative fatigue risk.

Estimate relative pilot fatigue risk using sleep, hours awake, time of day, duty length, and stress level. This free aviation tool is intended for safety awareness and personal self-assessment only.

Estimate Fatigue Risk

Enter a few basic factors to estimate a relative fatigue risk level for planning awareness.

Important: This tool is not a medical device, not a legal fitness-for-flight tool, and not a substitute for IMSAFE, company policy, or professional judgment. If you believe fatigue may affect safety, do not use this calculator as the deciding factor.

Fatigue Estimator

Sleep in Last 24 Hours (hours)

Hours Awake

Time of Day

Duty Length (hours)

Stress Level

How It Works

Inputs Considered:
Sleep, time awake, time of day, duty length, and stress

Output:
Relative fatigue score and estimated risk category

Planning Note:
This is a simplified awareness tool. Human fatigue is complex and depends on many factors that this estimator does not capture.

This tool is intended to encourage conservative decision making and better personal awareness.

What Is a Fatigue Estimator?

A fatigue estimator is a simple self-assessment tool that looks at common fatigue-related factors such as recent sleep, hours awake, time of day, and duty duration.

In aviation, fatigue matters because it can affect attention, memory, decision making, and overall performance. A tool like this can support awareness, but it cannot replace good judgment or official guidance.

Why Pilots Use a Fatigue Estimator

Encourage honest self-assessment before flight
Spot elevated fatigue risk conditions
Improve safety awareness during training and planning
Support discussion alongside IMSAFE and risk management
Promote conservative decision making when tired

Fatigue Estimator FAQ

Does this tell me whether I am fit to fly?

No. This tool only estimates relative fatigue risk and is not a determination of medical, legal, or operational fitness.

Why does time of day matter?

Fatigue often increases during circadian low periods, especially late at night and in the early morning hours.

Why do hours awake matter?

Longer wakefulness can reduce alertness and performance, even when a person feels functional.

Should I still use IMSAFE?

Yes. IMSAFE and sound judgment remain essential. This calculator is only a supplement for awareness.