Fatigue PRO
Assess your fatigue risk using the Karolinska Sleepiness Scale (KSS).
What is KSS?#
The Karolinska Sleepiness Scale is a validated 9-point scale used in aviation fatigue risk management:
| Score | Description |
|---|---|
| 1 | Extremely alert |
| 2 | Very alert |
| 3 | Alert |
| 4 | Rather alert |
| 5 | Neither alert nor sleepy |
| 6 | Some signs of sleepiness |
| 7 | Sleepy, but no effort to keep awake |
| 8 | Sleepy, some effort to keep awake |
| 9 | Very sleepy, great effort to keep awake |
How to Use#
- Select the KSS score that best describes your current state. Tap the info icon next to the KSS selector for a popup explaining the scale, its aviation context, and interpretation guidance.
- Optionally add notes about contributing factors (e.g. sleep debt, early report, jet lag).
- The result is color-coded:
- Green (1-5) – acceptable alertness level
- Orange (6-7) – elevated fatigue risk
- Red (8-9) – high fatigue risk, consider reporting a fatigue event
Purpose#
Use this tool to:
- Self-assess before and during duty
- Document fatigue levels for your personal records
- Support fatigue reports to your airline's safety department
Fatigue Model#
The fatigue prediction is based on the Three-Process Model (Åkerstedt & Folkard, 1997), which combines:
- Homeostatic process – sleep pressure that builds during wakefulness
- Circadian process – the body clock's natural alertness cycle
- Sleep inertia process – the grogginess period after waking
Timeline View#
A scrollable horizontal timeline visualizes your duty and sleep schedule:
- Duty blocks – shown as colored bars representing each flight or duty period
- Sleep blocks – estimated sleep periods based on your schedule
- WOCL bands – the Window of Circadian Low (typically 02:00--06:00 body clock time) is highlighted on the timeline to indicate periods of lowest alertness
- Risk zone background fills – the timeline background is color-coded by predicted KSS level:
- Critical (KSS > 7) – red
- High (KSS = 7) – orange
- Moderate (KSS = 6) – yellow
- Low (KSS ≤ 5) – green
Risk Factor Indicators#
Color-coded dots flag contributing risk factors for each duty period:
- Sleep debt – insufficient sleep in preceding days
- Early report – duty start before 06:00 local time
- Jet lag – significant time zone difference from home base
Settings#
- Adjustable sleep assumption – set the assumed nightly sleep duration between 5 and 10 hours to match your actual rest habits
- Body clock display – shows current body clock time based on your home base timezone
Next Flight Forecast#
For the upcoming flight, the tool displays the predicted KSS score at takeoff and at landing, giving you advance notice of expected fatigue levels before you report for duty.