Fatigue and alertness

Fatigue reduces attention, slows reactions and degrades decision-making — often without the pilot noticing.

Where fatigue comes from

• Sleep loss — too little sleep, or poor-quality sleep.
• Time awake — performance declines the longer you are awake.
• Circadian rhythm — the body's internal clock makes the early-morning low (roughly 02:00–06:00) the most vulnerable period.
• Workload — long or intense duty periods.

Microsleeps

A microsleep is a short, involuntary sleep episode of a fraction of a second to several seconds. You may not notice it. At 120 knots, a 3-second microsleep means about 185 metres flown without active monitoring.

Caffeine: a tool, not a cure

Caffeine can reduce sleepiness for a few hours, starting after roughly 20–30 minutes. But it masks fatigue rather than removing it — and it can disturb the recovery sleep you need later.

What really helps

1. Protect your sleep opportunities, especially before early starts.
2. Use honest self-assessment before every flight (for example IMSAFE: Illness, Medication, Stress, Alcohol, Fatigue, Eating).
3. Tell your crew if you are tired and increase cross-checking.
4. Report fatigue through your operator's system — it helps everyone.