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Physiology and fitness to fly: IMSAFE, fatigue, alcohol and night vision
You must not fly as remote PIC, at the controls or as a visual observer within 8 hours of alcohol, under its influence, at 0.04 percent alcohol concentration or more, or on a drug that affects your faculties. Before every flight run IMSAFE (Illness, Medication, Stress, Alcohol, Fatigue, and Emotion or Eating) and ground yourself if any item fails.
What does the FAA require of a drone pilot's health?
Part 107 has no medical certificate, but 14 CFR 107.17 bars you from manipulating the controls or acting as remote PIC, visual observer or direct participant if you know or have reason to know of a physical or mental condition that would interfere with the safe operation of the system. The study guide says that it is the remote PIC's responsibility to make sure all crewmembers are not participating while impaired, and that medical conditions such as epilepsy may also create a risk. The pilot decides, honestly, whether the condition is under control.
Sources (checked 2026-11-14): 14 CFR 107.17 (eCFR); FAA Remote Pilot sUAS Study Guide (FAA-G-8082-22).
How do I run the IMSAFE check?
The study guide calls IMSAFE a great mnemonic for a self-assessment before every flight: Illness, Medication, Stress, Alcohol, Fatigue, Emotion. AC 107-2A, in its sample risk assessment, writes the last letter as Eating (am I sufficiently nourished?) and gives the Alcohol question as "within the last 8 to 24 hours". The two documents differ on the last letter, so know both on the test.
| Letter | Question to ask | Source detail |
|---|---|---|
| I, Illness | Do I have any symptom that might affect me in flight? | AC 107-2A A.4.8.2 |
| M, Medication | Am I taking any prescription or over-the-counter drug? | Wait at least 48 hours after the first dose of a new medication before flying (study guide) |
| S, Stress | Any psychological or emotional factor that might affect performance? | Study guide ch 9, acute and chronic stress |
| A, Alcohol | Have I consumed alcohol in the last 8 to 24 hours? | 8 hours and 0.04 percent are the regulatory limits (91.17) |
| F, Fatigue | Have I had sufficient sleep and rest? | Study guide ch 9 |
| E, Emotion or Eating | Am I emotionally steady (study guide) and sufficiently nourished (AC)? | Study guide and AC 107-2A |
Sources (checked 2026-11-14): FAA Remote Pilot sUAS Study Guide (FAA-G-8082-22); FAA Advisory Circular 107-2A.
What are the alcohol and drug rules?
14 CFR 107.27 requires a person manipulating the controls, acting as remote PIC or acting as visual observer to comply with 14 CFR 91.17 and 91.19. Section 91.17 says no person may act as crewmember within 8 hours after consuming any alcoholic beverage, while under the influence of alcohol, while using any drug that affects faculties in any way contrary to safety, or while having an alcohol concentration of 0.04 or greater in a blood or breath specimen. Committing an act prohibited by 91.17(a) is grounds under 107.57 for denying a remote pilot certificate application for up to a year or suspending or revoking a certificate.
The study guide adds practical points. A pilot with a blood alcohol level of 0.04 or greater after 8 hours cannot fly until it falls below that amount, and being under 0.04 does not permit flying sooner than 8 hours after drinking. A hangover means the pilot is still under the influence. Considerable amounts of alcohol can remain in the body for over 16 hours. Even small amounts can impair judgment, coordination and vision, and as little as one ounce of alcohol can slow muscular reflexes. The guide recommends being more conservative than the regulations. See also drug and alcohol rules.
Sources (checked 2026-11-14): 14 CFR 107.27 (eCFR); 14 CFR 91.17 (eCFR); 14 CFR 107.57 (eCFR); FAA Remote Pilot sUAS Study Guide (FAA-G-8082-22).
What do medications do to a pilot?
The study guide notes that part 107 and sections 91.17 and 91.19 prohibit any drug that affects a person's faculties in any way contrary to safety. It singles out over-the-counter antihistamines and decongestants as having the potential for drowsiness and cognitive deficits, and says medications with diphenhydramine (for example Benadryl) cause drowsiness and a prolonged half-life, which lengthens how long side effects last. Even dietary supplements and "natural" products can contain substances found in medications.
The guide's rule of thumb: for any new medication, wait at least 48 hours after the first dose before flying to see whether side effects appear, avoid unnecessary or elective medications, eat regular balanced meals, bring a snack and water, sleep well and stay physically fit.
Sources (checked 2026-11-14): FAA Remote Pilot sUAS Study Guide (FAA-G-8082-22).
How do fatigue and stress affect a flight?
The study guide says fatigue is frequently associated with pilot error. Effects include worse attention and concentration, impaired coordination and a reduced ability to communicate, all of which hurt decisions. Acute fatigue is short term, and rest after exertion with 8 hours of sound sleep ordinarily cures it. Chronic fatigue is not relieved by rest and sleep and may need a physician. If you suffer from acute fatigue, you should not operate a small UA, and if fatigue appears during flight, no amount of training or experience can overcome it. Avoid flying without a full night's rest, after excessive working hours, or after an exhausting or stressful day.
Stress is the body's response to physical and psychological demands. Performance increases with the onset of stress, peaks and then falls off rapidly when stress exceeds what a person can cope with, according to the guide's ADM chapter. AC 107-2A lists small UAS stressors such as working with an inexperienced crewmember and interacting with the public and city officials. Chronic stress that exceeds coping ability means the pilot should not exercise airman privileges.
Worked example
A rough day on a roof inspection
Say you slept five hours, drove two hours to the site, and the client calls twice about the schedule. Run IMSAFE: fatigue and stress both fail. The honest answer is to delay or hand the flight to a rested remote PIC, or shorten it, because the guide says no amount of training overcomes fatigue once it is present.
Sources (checked 2026-11-14): FAA Remote Pilot sUAS Study Guide (FAA-G-8082-22); FAA Advisory Circular 107-2A.
How do I prevent dehydration and heatstroke?
The study guide describes dehydration as a critical loss of water. Causes include hot temperatures, wind, humidity and diuretic drinks such as coffee, tea, alcohol and caffeinated soft drinks. Signs are headache, fatigue, cramps, sleepiness and dizziness, and fatigue is the first noticeable effect. Flying for long periods in hot summer weather or at altitude increases the rate of water loss. The guide suggests drinking two to four quarts of water every 24 hours as a guide, notes that most people feel thirsty at a 1.5 quart deficit or a 2 percent loss of body weight, and warns that the thirst mechanism arrives too late and is turned off too easily.
Heatstroke is a condition caused by the body's inability to control its temperature. It may show up as dehydration symptoms or only on complete collapse. For prevention the guide says to carry ample water and drink at frequent intervals whether thirsty or not: one pint per hour for moderate heat stress and one quart per hour for severe heat stress.
Sources (checked 2026-11-14): FAA Remote Pilot sUAS Study Guide (FAA-G-8082-22).
What is hyperventilation and how do I fix it?
The study guide defines hyperventilation as excessive rate and depth of breathing leading to an abnormal loss of carbon dioxide from the blood. Symptoms include visual impairment, lightheadedness or dizziness, tingling, hot and cold sensations, muscle spasms and, in the worst case, unconsciousness. Pilots in an unexpected stressful situation may breathe faster without noticing. The cure is to restore the carbon dioxide level: slow the breathing rate, breathe normally, breathe into a paper bag or talk aloud. Recovery is usually rapid. This matters in a crisis such as a lost link, when a pilot's own breathing can make the situation worse.
Sources (checked 2026-11-14): FAA Remote Pilot sUAS Study Guide (FAA-G-8082-22); FAA Pilot's Handbook of Aeronautical Knowledge.
How does vision work for a remote pilot?
Vision is the most important sense for safe flight, according to the PHAK, and it is subject to limits such as illusions and blind spots. The study guide's scanning technique: look from right to left or left to right, starting at the greatest distance an object can be perceived and moving inward. Scan an area about 30 degrees wide at each stop, hold no stop longer than 2 to 3 seconds, and overlap the previous view by 10 degrees when moving to the next.
For VLOS flights, 14 CFR 107.31 requires unaided vision except for corrective lenses, and AC 107-2A says a vision aid such as binoculars may be used only momentarily. Each eye also has a blind spot where the optic nerve meets the retina. With both eyes open an object cannot sit in both blind spots at once, but with one eye blocked it can disappear.
Sources (checked 2026-11-14): FAA Remote Pilot sUAS Study Guide (FAA-G-8082-22); FAA Pilot's Handbook of Aeronautical Knowledge; FAA Advisory Circular 107-2A.
What changes at night and at dusk?
The PHAK describes three kinds of vision: photopic (bright light, cones), mesopic (dawn, dusk and full moon, cones and rods) and scotopic (low light, rods only). It calls the mesopic period the most dangerous for viewing because acuity decreases and color perception changes while cone sensitivity falls. Dawn and dusk are also when civil twilight flights happen, which Part 107 allows with an anti-collision light.
- Dark adaptation. The rods can take about 30 minutes to adapt fully to the dark, and a bright light can destroy the adaptation.
- Night blind spot. To see an object at night, look 5 to 10 degrees off center. Objects viewed longer than 2 to 3 seconds disappear, so keep the eyes moving.
- Protecting night vision. Use neutral density sunglasses before a night flight, keep screens dim, avoid bright lit areas and use dim white light for maps.
- Autokinesis. Staring at a single point of light against a dark background makes it appear to move, starting after about 8 to 10 seconds. Avoid fixating, scan, and do not stare at a light for more than 10 seconds.
- False horizon. Bright stars, city lights, a sloping cloud formation or shoreline lights can be mistaken for the real horizon.
- Other illusions. The PHAK also lists reversible perspective, size-distance illusion, fascination or fixation, flicker vertigo (light flickering at 4 to 20 cycles per second) and landing illusions.
See night operations for the lighting and training rules.
Sources (checked 2026-11-14): FAA Pilot's Handbook of Aeronautical Knowledge; FAA Remote Pilot sUAS Study Guide (FAA-G-8082-22).
Which facts show up on the test?
- 8 hours, 0.04 percent, and drugs that affect faculties.
- IMSAFE letters, and that the 107.17 duty rests on the person's knowledge of a condition.
- Hyperventilation symptoms and cure (breathe normally, talk or breathe into a bag).
- Dehydration, fatigue as its first effect, and that thirst is a late signal.
- Autokinesis and false horizon at night.
- The pilot is responsible for the crew's fitness too (study guide ch 9).
Next: aeronautical decision-making and crew resource management.
Sources (checked 2026-11-14): FAA Remote Pilot sUAS Study Guide (FAA-G-8082-22); 14 CFR 91.17 (eCFR); 14 CFR 107.17 (eCFR).
Related guides
- Aeronautical decision-making, CRM and human factors
- Part 107 drug and alcohol rules: 8 hours, 0.04 and refusing a test
- Part 107 night operations: lights, twilight and training
- Crew resource management for Part 107 crews
- All Part 107 guides
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Sources
- FAA Remote Pilot sUAS Study Guide (FAA-G-8082-22), checked 2026-11-14
- FAA Pilot's Handbook of Aeronautical Knowledge, checked 2026-11-14
- FAA Advisory Circular 107-2A, checked 2026-11-14
- 14 CFR 91.17 (eCFR), checked 2026-11-14
- 14 CFR 107.17 (eCFR), checked 2026-11-14
- 14 CFR 107.27 (eCFR), checked 2026-11-14
- 14 CFR 107.57 (eCFR), checked 2026-11-14
How this page was made: written by Certloom Learning from the sources above, with the rules checked against the current regulation text. Practice items are original questions from the app's reviewed bank. Spot an error? certloomlearning@gmail.com.