CRM Knowledge Base
The theory behind the reflex.
Ten concepts. Read them before the scenarios. Return to them after the debrief.
Concepts · 08
Fatigue and Performance
What it is
Fatigue degrades every cognitive capability relevant to safe flight: reaction time, decision speed, working memory, attention span, and the ability to detect and correct errors. Critically, fatigue also degrades the ability to accurately assess one's own fatigue — fatigued pilots consistently overestimate their performance capability.
Why it happens
Sleep deprivation and circadian disruption alter the neurochemistry of the prefrontal cortex — the part of the brain responsible for judgment, risk assessment, and impulse control. After 18 hours without sleep, cognitive performance is equivalent to a blood alcohol level of 0.05%. After 24 hours, it is equivalent to 0.10% — above the legal limit in most jurisdictions. The duty day regulations exist because these are not abstract statistics.
In the cockpit
You have slept four hours. You are on day three of three. The departure briefing took longer than normal. You lost your place once. The captain says "one more sector" and you hear yourself agree — not because you have assessed your fitness for duty but because agreeing is easier than the alternative. In the cruise you make an FMS entry error. You are not sure when your scan last felt fully active.
The counter-reflex
Self-reporting fatigue is a protected safety action under EASA ORO.FTL. It cannot be used against you. The decision to report is made before the sector — not after the briefing has started and the social pressure to fly has fully formed. Ask yourself at home, before leaving for the airport: "Am I fit for duty?" If the honest answer is no, the report is made then — not in the cockpit.
From the reports
Composite patterns from public EASA, AAIB, BEA, and NTSB occurrence data.
OCCURRENCE PATTERN
A first officer self-reported after a sequence of three early departures with minimum rest between duties that he had felt fatigued on the final sector but had not declared fitness concerns before departure. During the sector he made two FMS data entry errors, both identified by the captain. Post-event review of duty records showed total sleep in the 48 hours prior to the final sector was below recommended minimums. The first officer stated the primary reason for not self-reporting was concern about the impact on his colleagues and the disruption to the operation.
Pattern composite — public occurrence database [AAIB]
CRM finding: Fatigue — Non-declaration of fatigue state