Nineteen hours awake, a head cold and a pressurisation fault
Second pilot B has been awake since 04:00 local for a report time of 05:30. The flight is a 4-hour night sector departing at 22:30 local, the third sector of the day, with a 90-minute sit in between. B has a head cold and has taken a sedating antihistamine 6 hours before report; the drug's label warns of drowsiness for 24 hours and it is not on the operator's approved list. During the climb through FL160 the cabin altitude warning triggers and the cabin rate-of-climb indicator reads 2 500 ft/min. The captain elects to continue the climb to FL350 and to run the checklist at level-off. B reports tingling in the fingers and a feeling of unreality at cabin altitude 14 000 ft.
1. Was second pilot B fit to operate? Give the specific factors.
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No.
- Medication. A sedating antihistamine taken 6 hours before report, with labelled drowsiness for 24 hours, and not on the operator's approved list. This alone is disqualifying: a crew member cannot self-certify fitness while under a preparation known to impair psychomotor performance and alertness.
- Fatigue. Awake since 04:00 with a 22:30 departure - about 18.5 hours of wakefulness at brake release and around 23 by landing, inside the circadian low. Combined with a third sector and a short sit, the cumulative sleep debt is significant.
- Illness. An upper respiratory infection impairs Eustachian tube function, raising the risk of barotrauma during the descent, increases susceptibility to hypoxia and is in itself a reason to be off duty.
B should have been replaced before the first sector. The commander carries the responsibility for accepting the crew, and the operator's drug policy exists precisely to remove this judgement from the individual.
2. Assess the captain's handling of the pressurisation warning.
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Continuing to FL350 and deferring the checklist is indefensible.
- A cabin altitude warning during the climb, with a cabin rate of 2 500 ft/min (normal is a few hundred), means the cabin is not being controlled - an outflow valve, pack or seal failure.
- Climbing increases the differential pressure. If the outflow valve is stuck open, cabin altitude will track aircraft altitude, and at FL350 the time of useful consciousness is measured in tens of seconds, not minutes.
- The correct response is the memory procedure: oxygen masks on, establish crew communication, stop the climb, and descend to FL100 or the highest safe altitude, then run the checklist.
B's tingling fingers and feeling of unreality at a cabin altitude of 14 000 ft are early hypoxia. At that cabin altitude consciousness is not immediately at risk, which is exactly why the signs were allowed to develop instead of being treated as a warning to descend now.
3. What must happen after landing?
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- Occurrence report. A pressurisation failure with a cabin altitude warning is a reportable occurrence. File the operator's report and, where the state requires it, the mandatory occurrence report within the prescribed time.
- Drug and medical referral. B's use of a non-approved sedating medication must be recorded and referred to the aeromedical authority; self-medication with an impairing drug normally triggers a licence review.
- Data preservation. Preserve CVR and FDR data and the cabin pressure traces. Do not reset or clear the pressurisation system before engineering has read the fault codes.
- Company review. Examine the dispatch process that let a crew member report with a cold and a sedating drug, and the command decision that continued the climb against the memory items.
The lesson to carry into the exam: fitness to fly is a continuous judgement, and the commander's authority to refuse a sector is worth more than any schedule.