The IMSAFE Checklist: How to Know You Are Fit to Fly Today

Most preflight time goes to the airplane and the weather. IMSAFE is the part of the preflight that checks the person flying. The FAA Risk Management Handbook presents it as a way to spot aeromedical hazards before a flight [1], and the FAA's Fit to Fly material covers the same ground for pilots [8].

What the IMSAFE checklist is and when to use it

IMSAFE is a personal checklist pilots run before every flight to confirm they are fit to fly: Illness, Medication, Stress, Alcohol, Fatigue, and Emotion (some sources use Eating as the second E) [1].

It is a self assessment. There is no form to file and no one signs it off. The regulation behind it, 14 CFR 61.53, puts the duty on the pilot: if you hold a medical certificate, you may not act as pilot in command while you know or have reason to know of a medical condition that would make you unable to meet its requirements. If you fly an operation that does not require a medical certificate, the test is whether the condition would make you unable to operate the aircraft in a safe manner [2].

IMSAFE and PAVE work together. IMSAFE checks the Pilot, the P in PAVE [1]. Run it when you plan the flight, again the morning of the flight, and once more before you start the engine, because how you feel can change between the plan and the run-up.

The six IMSAFE questions, one letter at a time

Each letter below has one direct question, a few signs that point toward "not today," and the source behind it. The signs are examples, not a complete list.

Illness: symptoms that matter at altitude

Ask: Do I have any symptom, even a mild one, that could get worse or distract me in flight?

• Congestion that could block your ears or sinuses as pressure changes in a climb or descent.
• Fever, nausea, dizziness, or a headache you would not drive with.
• A condition you know about that would keep you from meeting your medical certificate requirements, or from operating the aircraft safely if you fly without one [2].

Source: FAA Risk Management Handbook, Chapter 3; 14 CFR 61.53; FAA Fit to Fly [1][2][8].

Medication: what the FAA says about OTC and prescription drugs

Ask: Have I taken anything in the last few days, prescription or over the counter, that could affect my judgment, alertness, or vision?

• The label warns of drowsiness or says to be careful driving or operating machinery [5].
• You started a new medication recently. The MedGuide calls for a 48 hour wait in most cases [4].
• You took a sleep aid, antihistamine, or cold medicine and have not checked the wait time [5][6].

Source: FAA MedGuide; FAA Do Not Issue and Do Not Fly guidance; FAA OTC Medications Reference Guide [4][5][6]. Details in the medications section below.

Stress: outside pressure that narrows attention

Ask: Is something on my mind today that will pull my attention away from flying?

• Trouble at work or at home that you keep thinking about.
• A deadline on the other end of the flight, which also shows up as External pressure in PAVE [1].
• Feeling rushed before you have even reached the airport.

Source: FAA Risk Management Handbook, Chapter 3; FAA Fit to Fly [1][8].

Alcohol: 8 hours is a floor, not a target (14 CFR 91.17)

Ask: When did I last drink, how much, and am I still feeling any effect?

• Less than 8 hours since your last drink. 14 CFR 91.17 prohibits acting as a crewmember within 8 hours after consuming alcohol [3].
• Still under the influence, even after 8 hours. The rule prohibits that too [3].
• Any chance your alcohol concentration is 0.04 or greater [3].

Source: 14 CFR 91.17(a) [3].

Fatigue: sleep debt, time awake and the flight home

Ask: How much did I sleep, how long will I have been awake when I land, and will I be flying home tired?

• Short or broken sleep the night before, or several short nights in a row.
• A long workday before an evening departure.
• A return leg that lands late, after the trip itself has worn you down.

Source: FAA Risk Management Handbook, Chapter 3; FAA Fit to Fly; NTSB ERA23FA164, where fatigue contributed [1][8][10].

Emotion and eating: what else you are carrying into the cockpit

Ask: Am I upset, angry, or grieving, and have I eaten and had enough water?

• A recent argument, loss, or piece of bad news.
• Skipped meals, or a long flight with no food or water on board.
• Wanting the flight to prove something, to yourself or to someone else.

Source: FAA Risk Management Handbook, Chapter 3; FAA Fit to Fly [1][8].

Medications and IMSAFE: 14 CFR 61.53, the FAA MedGuide and Do Not Fly

Medication is the IMSAFE letter with the most written guidance behind it. The FAA's Pilots and Medication page cites a 2011 study that found drugs or medications in 570 of 1,353 fatal pilots tested, or 42 percent, and 90 percent of those pilots were flying under Part 91 [7].

What 14 CFR 61.53 requires

The rule has two tests, depending on whether the operation requires a medical certificate [2]:

• Operations that require a medical certificate: a certificate holder may not act as pilot in command, or as a required pilot flight crewmember, while they know or have reason to know of any medical condition that would make them unable to meet the requirements for the medical certificate, or while taking medication or receiving other treatment for a condition that has that result [2].
• Operations that do not require a medical certificate: a pilot may not act as pilot in command, or as a required pilot flight crewmember, while they know or have reason to know of any medical condition that would make them unable to operate the aircraft in a safe manner [2].

Either way, a valid medical certificate or eligibility does not answer the question for today; 61.53 does.

FAA MedGuide (version 1.0, Oct 1, 2026): what it covers and does not

The FAA MedGuide comes from the FAA Office of Aerospace Medicine. The page says "This is version 1.0 of the MedGuide" and shows "Last updated: Thursday, October 1, 2026" [4].

• What it covers: version 1.0 lists only allowed medications [4]. Allowed is conditional: the MedGuide defines it as acceptable for flight duties provided the condition is stable and aeromedically acceptable and no adverse side effects are present [4].
• What it is not: the FAA says the MedGuide should not be used as the sole basis for aeromedical determinations, which require an individualized assessment [4]. A listed medication is not blanket clearance to fly.
• What it does not cover yet: later versions will add conditional and unacceptable medications [4]. A drug that is not on the list is not automatically allowed.
• New medications: in most cases a 48 hour wait applies after you start a new medication [4].
• The rule behind it: the MedGuide cites and links 14 CFR 61.53 [4].

The MedGuide page does not link the Do Not Fly list, so check that list separately [4][5].

Do Not Issue and Do Not Fly medications and the 5 half-lives wait rule

The FAA AME Guide keeps two lists [5]:

• Do Not Issue (DNI): medications for which an aviation medical examiner cannot issue a medical certificate.
• Do Not Fly (DNF): medications you should not fly on until a set time has passed.

The general Do Not Fly wait is 5 times the maximum pharmacologic half-life of the drug, which the FAA calls the preferred method. Only if half-life information is not available does the FAA use 5 times the maximum dosing interval instead [5]. Where the FAA tables list a wait for a specific medication, use that wait [5]. Diphenhydramine is a common example. NTSB final reports CEN24FA327 and CEN22LA024 cite the FAA statement that pilots should not fly within 60 hours of using diphenhydramine. See the FAA DNI and DNF page and the DNI and DNF tables (PDF) [5].

Reading an OTC label: the drowsiness and machinery warning

For over the counter drugs, the label is the first filter. The FAA says not to fly on any medication whose label warns of drowsiness or says to be careful driving or operating machinery [5]. The FAA OTC Medications Reference Guide (updated August 28, 2024) and the FAA pharmaceuticals page for pilots go further [6]. When in doubt, ask your aviation medical examiner before the flight, not after.

When one answer is a yes: raising your personal minimums

A yes on IMSAFE does not always mean the flight is off, and it does not always mean it is fine. It means the pilot side of the risk is higher today, so the margin elsewhere may need to be bigger. The table shows examples some pilots choose. It is not a set of instructions, and none of these is a substitute for staying on the ground when you are not fit to fly.

IMSAFE and weather: why an impaired pilot needs a bigger margin

Weather and pilot condition are not separate risks. A pilot who is tired or medicated has less in reserve for the moment the ceiling comes down or the visibility drops. The second NTSB case below shows that link: the probable cause names continued VFR flight into instrument conditions, and the contributing factor is the pilot's degraded judgment and performance due to fatigue [10].

That is why many pilots tie their personal minimums to how they feel that day, not only to their certificate and ratings. For how to set and use those limits, see Weather Risk and Personal Minimums.

IMSAFE, PAVE and the FRAT: where the pilot check fits

IMSAFE is not a separate system. It is the Pilot part of PAVE: Pilot, Aircraft, enVironment, External pressures [1]. A FRAT is where you write those hazards down and see the risk they add up to [1].

• IMSAFE asks whether you are fit today.
• PAVE sorts every hazard into four groups, with IMSAFE inside the P. See the PAVE risk assessment guide.
• A FRAT records the PAVE hazards for one flight. See what a flight risk assessment tool is and how to use one.

IMSAFE accident lessons: when the pilot was the weak link

The two cases below come from NTSB final reports. The facts and quotes are taken from those reports only. For a longer case study, see Into Thin Air.

Alcohol and three impairing medications: Cessna P210N, Colorado, 2016

On May 18, 2016, a Cessna P210N (N6609P) crashed near Sheridan Lake, Colorado, on a Part 91 personal flight. The pilot was fatally injured. NTSB case CEN16FA188 [9].

"The pilot's severe impairment from the combined effects of high levels of ingested alcohol as well as three impairing medications (zolpidem, lorazepam, and diphenhydramine), which resulted in his decision to attempt an aerobatic maneuver that the airplane was not approved for."

The NTSB findings include Alcohol - Pilot and Prescription medication - Pilot [9]. Two IMSAFE letters, Medication and Alcohol, are named in that probable cause. Read the NTSB final report for CEN16FA188 (PDF).

Fatigue and VFR into cloud: Piper PA-28-161, South Carolina, 2023

On March 25, 2023, a Piper PA-28-161 (N21480) crashed near Johns Island, South Carolina, on a Part 91 personal flight. The pilot was fatally injured. NTSB case ERA23FA164 [10].

"The pilot's decision to continue flight under visual flight rules into instrument meteorological conditions, which resulted in the pilot's spatial disorientation and loss of control. Contributing to the accident was the pilot's degraded judgement and performance due to fatigue."

This case ties the F in IMSAFE to the weather decision. Fatigue did not create the clouds, but the NTSB found it contributed to the decision to keep going into them. Read the NTSB final report for ERA23FA164 (PDF).

Printable IMSAFE card for your kneeboard

Print this section or copy it onto a kneeboard card. Answer each line honestly before every flight.

IMSAFE checklist card: six questions before every flight

• Illness: Any symptom that could get worse or distract me in flight?
• Medication: Anything taken in the last few days? Checked the MedGuide, the Do Not Fly wait and the label?
• Stress: Anything on my mind that will pull my attention away?
• Alcohol: More than 8 hours since my last drink, no effects left, and no chance my alcohol concentration is 0.04 or greater?
• Fatigue: Enough sleep? How long awake by landing, including the flight home?
• Emotion and eating: Settled, fed and hydrated?
• Any yes: Raise my personal minimums, change the plan, or stay home.

IMSAFE in the PlaneWX loop: Brief, Assess, Decide, Debrief

PlaneWX is decision support for general aviation pilots, built around one loop: Brief, Assess, Decide, Debrief. Here is where IMSAFE fits in each step, as described in the help center [11]:

• Brief. Start with the WX Score briefing. The WX Score runs the weather for your route and time against minimums, yours or the defaults. For an obviously low-risk flight, a pilot can decide from the briefing, and the FRAT if they use one.
• Assess. If the WX Score is low, the FRAT is where you identify the risks and decide on mitigations. IMSAFE is the Pilot factor, alongside Aircraft, enVironment and External pressures. The FRAT opens 4 hours before departure, so you rate how you actually feel that day.
• Decide. GO / NO-GO. If the score is low or concerns remain, pilots connect with a mentor, and mentors can require the FRAT. That conversation is the decision point. Either way, the pilot always makes the call.
• Debrief. Self Debrief after the flight: compare how you actually felt with your IMSAFE answers. Pilots who debrief a flight are about twice as likely to run a FRAT on the next one.

The briefing and the FRAT alone may not be enough. PlaneWX never recommends go or no-go. The pilot makes the call and also weighs NOTAMs, ATIS, PIREPs, other sources and their own judgment. On Pro Plus, the PlaneWX connector for Claude and Grok can help you cross-check what you are seeing (connector beta news).

Brief your next trip in PlaneWX or read how the PlaneWX FRAT works.

Common questions about the IMSAFE checklist

What is the IMSAFE self-assessment checklist used for?

It is used to decide whether you are fit to fly before each flight. IMSAFE walks through Illness, Medication, Stress, Alcohol, Fatigue and Emotion so you catch a pilot problem before it meets a weather or aircraft problem. It is a self assessment, and 14 CFR 61.53 puts the responsibility on the pilot [1][2].

What is an IMSAFE checklist?

An IMSAFE checklist is a personal fitness check pilots run before every flight. The letters stand for Illness, Medication, Stress, Alcohol, Fatigue and Emotion, and some sources use Eating for the second E. The FAA Risk Management Handbook presents it as a way to spot aeromedical hazards, the Pilot part of PAVE [1].

What does the IMSAFE checklist include in terms of medicine?

The M covers prescription and over the counter drugs. 14 CFR 91.17 prohibits crewmember duty while using a drug that affects your faculties contrary to safety. The FAA MedGuide lists conditionally allowed medications, usually with a 48 hour wait after starting one. Do Not Fly waits are 5 maximum half-lives, or 5 dosing intervals if half-life data is unavailable [3][4][5].

What is the PAVE checklist used for in aviation?

PAVE is used to sort the hazards of a planned flight into four groups: Pilot, Aircraft, enVironment and External pressures. IMSAFE is how you check the Pilot group. Pilots often record PAVE hazards in a FRAT to see how the risk adds up. See the PAVE guide [1].

What are the five safety checks?

There is no single FAA list called "the five safety checks." Pilots often mean the 5P check from the FAA Pilot's Handbook of Aeronautical Knowledge: Plan, Plane, Pilot, Passengers and Programming. The Pilot check is where IMSAFE fits, alongside PAVE and the FRAT, which cover the rest of the flight's hazards [12][1].

IMSAFE checklist glossary of terms

Every term below links to the FAA document that defines it. The same definitions appear when you hover, focus, or tap a dotted term on this page.

FRAT (Flight Risk Assessment Tool)

A form or checklist for recording flight hazards and the risk they add up to before you fly. Source: FAA Risk Management Handbook, Chapter 3, Using a Flight Risk Assessment Tool (FRAT)

IMSAFE (Illness, Medication, Stress, Alcohol, Fatigue, Emotion)

A personal fitness checklist that helps a pilot spot aeromedical hazards, the P in PAVE, before a flight. Source: FAA Risk Management Handbook, Chapter 3, Aeromedical

PAVE (Pilot, Aircraft, enVironment, External pressures)

The FAA risk checklist that sorts preflight hazards into four groups: the pilot, the aircraft, the environment, and external pressures. Source: FAA Risk Management Handbook, Chapter 1, The PAVE Checklist

Personal minimums

A pilot’s own set of rules and criteria for deciding whether, and under what conditions, to fly or keep flying. Source: FAA AC 91-92, 4.15

IMSAFE checklist references: sources cited in this guide

1. FAA‑H‑8083‑2A, "Risk Management Handbook." Federal Aviation Administration. 2022. Chapter 3, Aeromedical (IMSAFE) and Chapter 1 (PAVE). https://www.faa.gov/sites/faa.gov/files/2022-06/risk_management_handbook_2A.pdf
2. 14 CFR 61.53, "Prohibition on operations during medical deficiency." Electronic Code of Federal Regulations. Accessed October 11, 2026. https://www.ecfr.gov/current/title-14/chapter-I/subchapter-D/part-61/subpart-A/section-61.53
3. 14 CFR 91.17, "Alcohol or drugs." Electronic Code of Federal Regulations. Accessed October 11, 2026. https://www.ecfr.gov/current/title-14/chapter-I/subchapter-F/part-91/subpart-A/section-91.17
4. "MedGuide." FAA Office of Aerospace Medicine. Version 1.0, last updated October 1, 2026. Accessed October 11, 2026. https://www.faa.gov/ame_guide/medguide
5. "Do Not Issue / Do Not Fly." FAA Guide for Aviation Medical Examiners. https://www.faa.gov/ame_guide/pharm/dni_dnf. Tables (PDF): https://www.faa.gov/ame_guide/media/DNI_DNF_tables.pdf
6. "OTC Medications Reference Guide." Federal Aviation Administration. Updated August 28, 2024. https://www.faa.gov/pilots/medical_certification/media/OTCMedicationsforPilots.pdf. Pharmaceuticals for pilots: https://www.faa.gov/pilots/medical_certification/medications
7. "Pilots and Medication." Federal Aviation Administration. https://www.faa.gov/newsroom/pilots-and-medication
8. "Fit to Fly." Federal Aviation Administration. https://www.faa.gov/sites/faa.gov/files/2023-10_Fit_to_Fly.pdf
9. NTSB final report CEN16FA188, Cessna P210N, N6609P, Sheridan Lake, Colorado, May 18, 2016. National Transportation Safety Board. https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/93192/pdf
10. NTSB final report ERA23FA164, Piper PA‑28‑161, N21480, Johns Island, South Carolina, March 25, 2023. National Transportation Safety Board. https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/106955/pdf
11. PlaneWX Help Center: "WX Score," "FRAT," "Mentors," "The Risk Loop." PlaneWX. Accessed October 11, 2026. WX Score · FRAT · Mentors · The Risk Loop
12. "Pilot's Handbook of Aeronautical Knowledge," Chapter 2, Aeronautical Decision‑Making. Federal Aviation Administration. https://www.faa.gov/sites/faa.gov/files/04_phak_ch2.pdf

#FlySafe is a campaign of the FAA and the General Aviation Joint Steering Committee. This page is independent PlaneWX education. See the GAJSC #FlySafe page.