5.3 Medical Fitness, Alcohol, Medication & Fatigue

Fitness Is an Operational Control

A2 operations take place near uninvolved people, often in visually cluttered and commercially pressured environments. A pilot’s condition is therefore a direct ground-risk control. UAS.OPEN.060 states that a remote pilot must not perform duties under the influence of psychoactive substances or alcohol, or when unfit because of injury, fatigue, medication, sickness, or other causes.

The Open category does not prescribe a conventional aviation medical certificate for ordinary remote pilots. That does not mean there is no medical standard: the practical standard is whether the person can perform the task safely. The CAA’s guidance compares the judgment to considering whether one is fit to drive or cycle, while making clear that the pilot remains responsible.

Alcohol and Psychoactive Substances

The reliable rule is do not drink and fly. Alcohol can reduce judgment, tracking accuracy, reaction speed, depth perception, coordination, and willingness to abort. Impairment may remain after the obvious feeling of intoxication has gone, including after poor sleep or a hangover.

Psychoactive substances include illegal drugs and other substances that affect perception, mood, cognition, or behaviour. A legal prescription can still impair flight performance. Legality of possession is not proof of fitness to fly. Do not build a personal “safe amount” from guesswork. If a substance may be affecting performance, do not act as remote pilot or essential observer.

Medication and Sickness

Prescription and over-the-counter medicines may cause drowsiness, dizziness, blurred vision, tremor, agitation, poor coordination, or impaired judgment. They may interact with alcohol, other medicines, heat, or dehydration.

Read patient-information warnings and ask a pharmacist or clinician when an effect is uncertain. A label saying “non-drowsy” is not a guarantee for every person, and a familiar medicine can behave differently when combined with illness or sleep loss.

Sickness itself matters. Fever, migraine, severe pain, nausea, respiratory symptoms, low blood sugar, dehydration, anxiety, or reduced concentration can undermine VLOS and decisions. If coughing, pain, or urgency is likely to pull attention from the aircraft, change the crew or postpone.

Injury and Functional Limitations

A painful wrist can compromise precise stick inputs; a neck injury can limit the airspace scan; damaged corrective lenses can make VLOS impossible. Mental-health symptoms or acute stress can also impair attention and judgment.

Ask a functional question: Can I perform every required action, continuously, in this environment? If the answer depends on hoping the condition will not matter, the operation is not ready.

Fatigue

Fatigue reduces vigilance, memory, reaction time, accuracy, and the ability to recognise deteriorating risk. It can come from:

• inadequate or interrupted sleep;
• long duty periods or early starts;
• driving to the site and then flying;
• repeated high-concentration sorties;
• heat, cold, wind, rain, glare, and dehydration;
• monotonous monitoring;
• complex camera and client tasks;
• lone working without task sharing; and
• cumulative workload across several days.

The official syllabus explicitly links fatigue to duration and workload, including outdoor and lone working. A pilot may be awake yet unable to sustain the scan and judgment required near people.

Plan breaks, water, food, shade or warm shelter, and realistic sortie lengths. Rotate trained crew where possible. Landing for a break is a mitigation; pushing until concentration collapses is not professional endurance.

Crew Health

An observer, marshal, or assistant performing a safety-critical role must also be fit. If the observer cannot see clearly, communicate, stay attentive, or move safely at the site, the planned observer arrangement fails. Replace the person, redesign the operation so the role is unnecessary, or stop. A client is not automatically trained crew.

Before and During Flight

Use a short personal check:

• Am I free from alcohol or impairing substances?
• Is illness, injury, medication, or stress affecting me?
• Did I sleep enough, and how long has the duty day been?
• Can I maintain VLOS, scan, control, and judgment?
• Is the crew equally capable?
• What signs will trigger a break or landing?

Fitness is dynamic. A migraine, heat stress, dizziness, sudden fatigue, or medication effect can emerge after take-off. If performance degrades, increase safety margin and land as soon as practicable.

Pressure Scenarios

Cold medicine. The label warns of drowsiness and the pilot has never used it. Do not test the effect during an A2 job; obtain advice and postpone or use a fit replacement.

Long day. After a pre-dawn drive and six sorties, the pilot misses observer calls. Battery and weather are good, but human performance is not. Land and stop or rotate crew.

Customer insistence. The pilot is feverish and cannot concentrate. The deadline has no regulatory effect; postpone.

Injured hand. A wrist brace limits one control axis. Automation cannot be assumed to cover every emergency. Unless the person is genuinely fit for safe control, do not fly.

The exam rule is direct: unfit means no duty.