The module closes with the substances that degrade a pilot from the inside (tobacco, caffeine, alcohol, medication, and the aircraft's own chemistry) and with the moment all such degradation points toward: a crew member incapacitated in flight, and the drills that keep that event survivable.
Tobacco
Smoking's aviation cost is mostly a carbon monoxide story. Burning tobacco loads the blood with CO, and a 20-a-day smoker carries a carboxyhaemoglobin level of about 7 percent: an oxygen-carrying penalty equivalent to sitting 4,000 to 5,000 feet higher than the aircraft. Add a normal cabin altitude of 6,000 to 8,000 feet and the smoker's blood is behaving as if at up to 12,000 feet: mild anaemic hypoxia on every sector, with the slowed reactions that implies. The syllabus lists the rest of the bill: respiratory damage (lung cancer, breathing problems), cardiovascular damage (circulatory problems, raised heart-attack risk), reduced resistance to hypoxia, reduced tolerance of G forces, and degraded night vision — the rod cells' oxygen hunger from the vision lesson, taxed twice.
Caffeine
The world's most widely used drug is a central nervous system stimulant, and crews run high intakes by lifestyle alone. The exam wants a number: performance can degrade at a dose as small as about 200 milligrams, roughly two cups of coffee, and the recommended crew ceiling is about 250 to 300 milligrams a day. Regular heavy intake breeds dependence, insomnia and hypertension; the drug is also a diuretic, feeding the dehydration the previous lesson warned about. And coffee has company: tea, cocoa, chocolate and cola-type soft drinks all carry caffeine, as do many cold, allergy and migraine preparations — a pilot counting cups can still be over the ceiling without noticing.
Alcohol
The regulatory line first: the maximum blood alcohol for flight crew is 20 milligrams per 100 millilitres of blood — a quarter of the classic UK driving limit, and research justifies the severity: at 40 mg/100 ml, half that driving limit, pilot errors already rise significantly. Behind the limit sits the standing guidance of at least 8 hours from drinking to flying after small amounts, proportionally longer after more, and the prudent rule of 24 hours' abstinence before flight.
What alcohol does maps cleanly onto the syllabus list: it impairs the ability to reason and judge, it strips inhibitions and self-control (with a false sense that performance has improved), it degrades vision, it disturbs the balance organs and feeds sensory illusions, it wrecks sleep patterns (REM sleep is degraded and waking comes early — the previous sleep lesson's currency, debased), and it heightens susceptibility to hypoxia, so every effect worsens with altitude. Taken with other drugs the results are unpredictable: each can potentiate the other, and the combination is absolutely prohibited.
The accounting units: one unit is roughly half a pint of beer, a glass of wine or a single measure of spirits, and the body eliminates about one unit per hour (more precisely, blood alcohol falls at about 15 mg/100 ml per hour). Nothing accelerates it: coffee, fresh air and showers change the drinker's feelings, not the blood, and sleeping actually slows the burn. The damage thresholds for the body run at 5 units a day or 21 a week for men, 3 a day or 14 a week for women — sustained intake above these levels causes permanent organ damage, licence aside.
Alcoholism
Alcoholism, by the WHO's definition, is drinking that repeatedly damages a person's physical, mental or social life, and its core feature is loss of control. Aircrew carry a higher-than-average risk, and the syllabus wants the reasons: social isolation on layovers, boredom, high income, easy access to cheap duty-free alcohol, a crew drinking culture, and the habit of using alcohol to unwind or as a sleep aid — which the sleep lesson already exposed as counterfeit. The warning signs form a recognisable portrait: drinking alone, gulping the first drink, preoccupation with the next one, defensiveness when challenged, protecting the supply, memory blanks, morning shakes, rising tolerance and binges.
If a colleague shows that portrait, the syllabus asks what you would actually do: the recommended first move is a prompt, frank and positive direct approach, made in the knowledge that help exists and that a treated pilot can return to flying. Where the direct approach is not possible, inform the company's aviation medical specialist or fleet manager. The treatment's foundation is the alcoholic's own admission of the illness, and its only realistic goal is total abstinence — controlled drinking does not come back.
Medication
Most drugs have side effects, individuals vary, and packaging advice never contemplates a cockpit — which is why the rule is that aircrew take only medication prescribed by a doctor who knows aviation, and why self-medication is doubly dangerous: it adds the drug's side effects to the untreated hazards of the illness itself. The over-the-counter shelf is the trap the syllabus names, and its worst offender is the antihistamine family in cold, flu, hay fever and allergy remedies: drowsiness and dizziness, often unnoticed by the sufferer, sometimes returning after a period of apparent alertness. Around it stand the supporting cast: nasal decongestants built on stimulants, antacids whose atropine disturbs vision and whose bicarbonate liberates gas for the climb, diarrhoea remedies built on opiates, weight-control pills built on amphetamine-type stimulants, and aspirin in excess bleeding the stomach.
Two rules close the pharmacy. A drug the pilot has never used before is never tried for the first time close to flying: it gets a ground trial under aeromedical advice first, exactly as the sleep lesson required of hypnotics (and after anaesthetics the aircraft waits: at least 12 hours after a local, 48 after a general). And the general rule the syllabus quotes deserves its capitals: if a pilot is so unwell as to require medication, then the pilot should consider themselves unfit to fly — the illness disqualifies once, and the drug disqualifies again.
The aircraft's own poisons
The machine carries materials that hurt when uncontained, and the syllabus wants them listed: mercury (corrosive, toxic vapour, and a structural emergency in its own right, since it destroys aluminium by amalgamation), battery electrolyte and its vapours, fuels, lubricants and hydraulic fluids whose vapours bring drowsiness, skin damage and nervous-system effects, anti-icing fluid (ethylene glycol, a kidney poison), and fire-extinguishing agents such as BCF, which in a closed space can suffocate, dizzy and eventually coma the people it protects.
Burn the cabin and the list changes: furnishings, plastic and foam upholstery, and plastic-coated electrical wiring all give off toxic fumes when heated, carbon monoxide among them, dense enough to kill — a cabin fire's smoke is a poison event before it is a heat event. Short of fire, there is the fume event: engine oil or hydraulic fluid leaks past worn seals into the bleed-air supply feeding the air conditioning, announcing itself as a hazy cabin and an oily, old-socks smell. The exposed can suffer eye and airway irritation, headache, dizziness, nausea and degraded thinking, up to incapacitation; the flight-deck response is oxygen masks at 100 percent and a landing, with the event reported so the leak is found.
Incapacitation in flight
Everything in this module converges here. The first principle the syllabus states: incapacitation is most dangerous when its onset is insidious. An obvious collapse announces itself and triggers the drill; a subtle incapacitation leaves a pilot upright, apparently well, perhaps unaware of the problem, operating below standard at exactly the moment nobody is checking. The causes are humbler than the imagination suggests — the ICAO survey table is dominated not by heart attacks but by the stomach.