Fatigue, Duty Limits and a Commander Who Wants to Go

The arithmetic alone settles most of it.

• Duty from 09:00 to the planned end at 23:15 = 14 h 15 min.
• Maximum duty = 13 h 00 min; with the full one-hour discretion = 14 h 00 min.
• The planned sector therefore exceeds even the discretionary maximum by 15 minutes, before any fatigue consideration.

Two independent reasons the discretion is unavailable:

1. It is not unforeseen. The fifth sector is on the published roster and was planned at the start of duty. Discretion exists for delays, diversions and technical problems that arise on the day, not to absorb a rostered sector that does not fit the scheme.
2. The precondition fails. The discretion may only be used where the commander is satisfied there is no fatigue. Documented sleep debt, a 02:30 disturbance and an observed microsleep in cruise make that satisfaction impossible to hold honestly.

Conclusion: the sector cannot be dispatched as planned. The correct course is to tell the operator's duty office now, before boarding, and request either a replacement crew or a rest period that satisfies the minimum rest requirement. Note that the answer would be the same even if the figures had come out at 13 h 55 min, because the discretion's precondition is still not met.

The evidence is specific, not a general worry.

• Acute sleep loss. About five hours against a normal eight, following an interrupted night, gives measurable degradation in vigilance and reaction time - comparable in effect to a modest alcohol level, though the impairment is different in kind.
• Circadian low. A 23:00–01:00 departure sits in the window where alertness falls steeply; the body is being asked to work through the period in which it is programmed to sleep, after already being awake for 14 hours.
• Observed microsleep. Eyes closing for several seconds in cruise is a clinical indicator of severe sleepiness, not a joke. It predicts involuntary lapses of attention of 10–30 seconds, which at cruise is several miles of unmonitored flight and during approach is the whole of a descent.
• Sector length is irrelevant. "Only an hour and twenty" contains the highest-workload phases - departure, climb, descent, approach, landing - and an approach after a short night is exactly where a lapse is least survivable. Short sectors also remove the rest opportunity that a long cruise might offer.
• Conclusion: the crew is not fit for the duty. Fatigue is a threat that cannot be managed by intention, and the go/no-go decision must be made on evidence, not on willingness.

Assertiveness with evidence, then escalation - not silence.

• Raise it directly and privately first, using facts not adjectives: "I had five hours' sleep, I saw you nod off in the cruise, and the duty would run to 14 h 15 against a 13-hour limit with a one-hour discretion that doesn't apply here." Then state the conclusion: "I don't think either of us is fit to fly this sector."
• Use a structured tool if the message is not landing - e.g. PACE (Probe, Alert, Challenge, Emergency) or the CUS assertiveness ladder - and escalate the wording rather than repeating the same sentence at the same volume.
• If he still insists: do not board and do not operate. The commander's authority does not include the power to override the FTL scheme or to declare a fatigued crew fit. State that you are unfit for the sector, note the time, and contact the duty office and, if necessary, the company's safety/occurrence channel. A commander can act alone, but he cannot require you to act against your own fitness assessment.
• Afterwards: file a fatigue report through the SMS. This is a protective, just-culture report - the purpose is to fix the rostering and the hotel, not to punish the commander. Two fatigue reports from one crew are the data that change a roster.