Fatigue, a Long Drive and a Night Sortie
You are a remote pilot who drove 5 hours to a site, arriving at 16:00 after a poor night's sleep of about 4 hours. You flew two 40-minute sorties in the late afternoon in 32 °C heat with no shade. At 20:30 the client asks for one more flight to capture the sunset and the blue hour. You have had one sandwich and two coffees since morning. You feel alert but notice you have been yawning, your eyes are gritty, and you twice misread the battery percentage on the controller in the last sortie. The site is a construction compound with floodlights, moving plant, and a 30 m crane. The forecast is for the wind to drop to 2 kt after sunset.
1. Assess the human-performance factors and decide whether to accept the third sortie. Justify your decision.
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The decision should be to decline the sortie as proposed, or to accept only a short, tightly bounded flight after a proper break. The reasoning:
Sleep debt. Four hours of sleep the previous night creates a measurable performance decrement. The effects of sleep loss are most pronounced in the late evening and early morning, exactly when the blue-hour sortie would occur, and they interact with circadian low points.
Fatigue from heat and driving. Five hours of driving plus two 40-minute sorties in 32 °C heat with no shade add physical and mental fatigue. Dehydration from one sandwich and two coffees worsens it; caffeine masks fatigue but does not remove it, and its effect fades.
Warning signs already present. Yawning, gritty eyes, and two misreads of the battery percentage are objective signs of degraded attention and visual performance. Misreading a critical parameter twice is a strong indicator that the pilot's monitoring is unreliable.
Risk factors of the sortie. Night, floodlights causing glare, moving plant, a 30 m crane, and a new environment. Night operations demand more visual scanning and more careful see-and-avoid, which is precisely what fatigue degrades.
Decision. Decline the third sortie. If the client insists, the only defensible option is a short flight (under 10 minutes), within a pre-briefed area clear of the crane and plant, after a 30-minute rest with water and food, with a second person acting as observer, and with a hard stop if any further error occurs. Even then, the pilot should recognise that the safest answer is no.
2. What controls would you put in place if the client overrides your refusal and you decide to fly a short sortie?
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If a short sortie is flown despite the fatigue, the controls must reduce the chance that a fatigue-induced error becomes an accident:
- Rest first. A 30-minute break with water and food, away from the sun and noise, before the flight. Do not launch immediately after the drive or the earlier sorties.
- Limit exposure. Cap the flight at 10 minutes and one battery, with a pre-briefed hover point and a fixed return time. Short duration limits the window in which fatigue can matter.
- Reduce task load. Use an observer whose only job is to watch the aircraft and the airspace, and who is in continuous communication with the pilot. Do not ask the pilot to manage the camera and the aircraft simultaneously.
- Simplify the environment. Define a clear flight area away from the crane and moving plant, with a no-fly boundary briefed to the client. Use the floodlights for orientation, not for looking at the aircraft.
- Checklists and cross-checks. Read battery and link figures aloud and have the observer confirm them, because the pilot has already misread them twice.
- Hard stop criteria. Any further parameter misread, any loss of orientation, or any difficulty holding a stable hover ends the flight immediately.
- Honest debrief. Record the fatigue in the flight log and treat the decision as a lesson: the original plan should have included a rest day or a second pilot.