Fatigue and Automation Failure on a Night Approach
A two-pilot crew is operating a night cargo flight with four sectors. The captain slept 4 hours in the last 24 and has been on duty since 06:00; it is now 02:30 the next day. The first officer had 8 hours' sleep and is relatively alert. The third sector was delayed 2 hours by maintenance. On final approach at 02:40, the autopilot disconnects unexpectedly and the captain says, 'I'm fine, just keep it simple.' The captain's responses are slow and he has twice selected the wrong mode. The weather is at minima, runway visual range 550 m, and the crew is cleared for an ILS approach. The company's fatigue risk management guidance says that a crew member who reports microsleeps must not act as pilot flying.
1. Identify the fatigue-related threats and explain why the captain's statement 'I'm fine' is unreliable.
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The captain has had 4 hours' sleep in 24 hours and has been on duty since 06:00; at 02:30 that is 20.5 hours of duty, in the circadian low. Two hours of delay and four sectors add cumulative fatigue. Slow responses, twice selecting the wrong mode, and microsleeps are objective signs of impairment. Fatigue impairs the ability to self-monitor, so the captain's self-assessment is unreliable: the same impairment that causes the errors also reduces insight and motivation to admit unfitness. The statement 'keep it simple' is a warning sign, not reassurance. The FO's relatively fresh state does not remove the risk, because the captain may still be making decisions and may be the pilot flying.
2. What should the FO do, and what is the safest outcome for the approach?
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The FO should take control positively, using a clear call such as 'I have control', and direct a go-around rather than continue to minima. The company guidance says a crew member reporting microsleeps must not act as pilot flying, so the captain must be removed from the PF role. The FO should configure for the missed approach, advise ATC of fatigue and request priority, and divert to an airport with better weather and a longer runway. If the captain resists, the FO should use graded assertion, state the concern and the intended action, and if necessary declare an emergency. The safest outcome is a stable diversion, not a minimum-visibility approach with an impaired captain. A report should be filed after landing.
3. How should the FO use graded assertiveness if the captain insists on continuing?
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Use a graded sequence: first a clear observation ('Captain, you have missed two mode selections and I saw you nod off'), then a concern ('I am not comfortable continuing this approach'), then a stated action ('I am taking control and going around'). If the captain still insists, use the emergency authority: declare an emergency, take control, and land at the nearest suitable airport. The FO should not be drawn into a debate on short final. The key is to act early, before the aircraft is at minima, and to use standard calls so ATC and the captain understand. After landing, the FO should ensure the captain is assessed and the event is reported through the safety system.