When must I not fly, and when must I stop?

Recognise the two points at which the regulation takes the decision out of your hands: when you are unfit to act as crew, and when safety is endangered.

Both provisions are written as absolute prohibitions with no exception and no threshold, which is unusual even in Part IX. Neither leaves room for a judgement call about whether the risk is acceptable.

• You know which duties make you a crew member, because the fitness rule binds crew rather than only the pilot. CAR 901.19
• You accept that "likely to suffer from fatigue" is a standard you apply to yourself before flying, not one that is measured afterwards. CAR 901.19

No person may act as a crew member of a remotely piloted aircraft system if the person is suffering or is likely to suffer from fatigue, or is otherwise unfit to perform properly the person's duties. CAR 901.19

Two limbs, and the second is deliberately open. "Otherwise unfit" is not defined, so it covers illness, medication, injury, stress, alcohol — anything that makes you unable to perform your duties properly. The test is your capacity to do the job, not a diagnosis.

The first limb is the one people under-read. It prohibits acting as crew when you are likely to suffer from fatigue, not only when you already are. A pilot starting a long day's work on too little sleep is caught by it before the fatigue bites.

Note also who it binds: any person, and any crew member. A visual observer is a crew member, so the rule applies to them as squarely as to the pilot.

A pilot must immediately cease operations if aviation safety or the safety of any person is endangered or likely to be endangered. CAR 901.16

This is the strongest obligation in the operating rules, and its wording is exact:

• the trigger is danger or the likelihood of danger — the same "likely" construction as the fatigue rule;
• the duty is to cease, not to mitigate, reduce altitude, or continue carefully;
• it applies to the safety of any person, not only to aviation safety, so a risk to somebody on the ground engages it;
• it says immediately.

There is no balancing test here. The section does not ask whether the flight could still be completed safely with care; it asks whether safety is endangered or likely to be, and if so, the flight stops.

The AIM states the same duty in the same terms — becoming aware of any situation that endangers aviation safety or the safety of persons on the ground means the operation must immediately cease until it is safe to continue — and it is the page where the penalties sit. AIM 3.2.4

"Otherwise unfit" is deliberately open, but the AIM fills in the parts that have figures attached, and they are the examinable ones.

Alcohol. It is strictly prohibited to act as a pilot or crew member of a system within 12 hours after consuming an alcoholic beverage, while under the influence of alcohol, or while using any drug that impairs a person's faculties. AIM 3.2.7

And the criminal law sits underneath it. Part VIII.1, section 320.14(1) of the Criminal Code prohibits acting as a pilot or crew member while the ability to operate is impaired to any degree by alcohol, drugs, or a combination of both. AIM 3.2.7

Note the difference in construction: the Regulations work in hours and states, the criminal provision works in degrees of impairment, and "to any degree" is not a tolerance. AIM 3.2.7

Prescription drugs. A pilot who takes them has a duty to ensure they do not alter the ability to engage safely in operations. Where there is doubt, it is each individual's responsibility to consult a physician, and to advise other members of the team if it is deemed necessary. AIM 3.2.7

Cannabis. It became legal for recreational and medical purposes in Canada in October 2018, and it has the potential to impair and adversely affect aviation safety. All pilots and flight crew members — including visual observers — must abstain from cannabis use for at least 28 days when conducting operations with a system. AIM 3.2.7

Fatigue. The AIM treats it as as dangerous as drugs or alcohol, and harder to detect: it influences judgment, motor response and mental capability, and its effects can be present without the person realizing it. Sleep is not the only factor — lack of sleep, work-related stress, family issues, emotional state and general health all contribute. Transport Canada publishes a Fatigue Risk Management System (FRMS) Toolbox for Canadian aviation. AIM 3.2.7

Fatigue, alcohol and drugs are not the whole list: illness and many other conditions may diminish a crew member's ability to perform their functions and render them unfit. And the responsibility is placed on the individual: it is the responsibility of individual crew members to conduct a self-assessment to ensure they are fit before accepting any duties related to the operation. AIM 3.2.7

The AIM offers a checklist for that self-assessment — IM SAFE — with the instruction that if the answer to any question is "Yes", you are likely not fit to act as a crew member: AIM 3.2.7

Letter	Question
I — Illness	Are you suffering from any illness that could impair your ability to complete your duties? AIM 3.2.7
M — Medication	Are you under the influence of any drugs — over-the-counter, prescription or recreational — that will impair your ability to complete your duties? AIM 3.2.7
S — Stress	Are personal or professional matters causing stress to the point that you are distracted or otherwise impaired? AIM 3.2.7
A — Alcohol	Have you consumed any alcohol within the previous 12 hours? AIM 3.2.7
F — Fatigue	Are you feeling tired? You should have had sufficient rest in the previous 24 hours and should feel alert. AIM 3.2.7
E — Eating and drinking	Are you feeling hungry or thirsty? You should be adequately nourished and hydrated. AIM 3.2.7

Read F and E together and the checklist is wider than most people expect: it asks about rest in the previous 24 hours and about being nourished and hydrated, not only about being sober. AIM 3.2.7

And there is a reporting duty on top of the self-assessment: the pilot in command of the operation must be informed as soon as possible of any incapacitation of any of their crew members, so that the necessary measures can be taken. AIM 3.2.7

The penalties come in two tiers, and the difference is worth noticing. Failing to abstain from acting as a crew member while unfit may result in individual penalties of up to $1,000 and corporate penalties of up to $5,000. Acting as a crew member within 12 hours of consuming alcohol, or while under the influence of drugs or alcohol, may result in individual fines of $5,000 and corporate penalties of $15,000 — three times as much at the corporate level. AIM 3.2.7

You are compliant only when all of the following hold:

• No crew member is acting while suffering, or likely to suffer, from fatigue CAR 901.19
• No crew member is otherwise unfit to perform their duties properly CAR 901.19
• Operations cease immediately if aviation safety or the safety of any person is endangered or likely to be endangered CAR 901.16

Situation	What applies
You slept four hours and feel fine	You are likely to suffer from fatigue — the rule is engaged CAR 901.19
A visual observer is unwell	They are a crew member, so 901.19 applies to them CAR 901.19
A member of the public walks under your route	Safety of a person is endangered — cease immediately CAR 901.16
A manned aircraft enters your area and you could avoid it carefully	Safety is likely to be endangered — cease, do not manage it CAR 901.16
You feel tired but the flight is nearly done	The rule has no allowance for finishing the job CAR 901.19

Warning Two words carry most of the weight in this lesson: immediately and likely. 901.16 requires operations to cease immediately when safety is endangered or likely to be, and 901.19 catches a crew member who is likely to suffer from fatigue. Both obligations begin before the harm does. CAR 901.16 CAR 901.19

Symptom	Likely cause	What to do
You continued a flight to finish a job	901.16 requires operations to cease, not to be completed carefully	Land and stop CAR 901.16
You treated the fatigue rule as applying only to the pilot	It binds any person acting as a crew member	Apply it to observers and other crew too CAR 901.19
You waited until you felt tired	The rule bites when fatigue is likely, not when it arrives	Assess before you start CAR 901.19
You reduced altitude instead of stopping	Ceasing is required; reducing risk is not the same as ceasing	Stop the operation CAR 901.16

Practise: Crew fitness and the duty to cease

• CAR 901.16 — Flight Safety
• CAR 901.19 — Fitness of Crew Members
• AIM RPA 3.2.7 — Fitness of Crew Members
• AIM RPA 3.2.4 — Flight Safety
• Consolidation: CARs current to 2026-09-21