Fatigue, Hypoxia Symptoms, and the Go/No-Go Decision
You are a private glider pilot who worked a night shift and slept 4 hours. You arrive at the club at 09:00 for a planned 5-hour flight in a mountain area with cloud base forecast at 2200 m and strong thermals. You feel alert but have had two coffees and no breakfast. During the flight, at 2500 m, you notice a mild headache, a feeling of warmth, and that you are breathing faster than usual. Your variometer shows a steady climb. You are 40 minutes into the flight and 15 km from the nearest suitable field. Your oxygen equipment is not fitted. The task requires you to cross a ridge at 2600 m before turning for home.
1. Interpret the symptoms and decide what to do.
Read the worked answer
The symptoms - headache, warmth, and increased breathing rate at 2500 m - are consistent with early hypoxia, and they are also consistent with fatigue and dehydration after a short sleep and no breakfast. The two causes are not mutually exclusive, and the safe assumption is that both are present.
At 2500 m, the partial pressure of oxygen is low enough that an unfit or tired pilot can show symptoms, particularly with a raised metabolic demand. The warmth and fast breathing are also consistent with hyperventilation, which can itself be triggered by anxiety or by the early stages of hypoxia.
The correct action is to descend immediately to a lower altitude, stop the climb, and turn toward the nearest suitable field. Do not continue to 2600 m to cross the ridge. Descending reduces the hypoxic load and gives you time to assess whether the symptoms resolve. If they do not resolve on descent, treat the situation as an emergency and land as soon as possible.
The judgement tested is not to rationalise symptoms as 'just fatigue' when the altitude and the workload both raise the risk.
2. Explain the pre-flight factors that should have changed the go/no-go decision, and how you would plan the flight differently.
Read the worked answer
The pre-flight factors were all present before launch: 4 hours of sleep after a night shift, no breakfast, two coffees, a 5-hour flight, and a mountain task with a ridge crossing above 2500 m without oxygen. Each is a known fatigue or hypoxia risk factor, and together they should have produced a no-go or a substantially reduced flight.
A sound plan would have:
- Set a maximum flight time consistent with the sleep obtained, and a hard turnaround time.
- Eaten and hydrated before flight, and limited caffeine.
- Planned the task to stay below the altitude at which oxygen is required, or carried oxygen and been trained in its use.
- Built in a ridge-crossing decision point with an alternative route that stays lower.
- Flown with another pilot or informed someone of the plan and the return time.
The judgement tested is that fatigue and hypoxia are cumulative and interact; a pilot who feels alert on the ground can still be impaired in the air, and the decision must be made before launch.