IMSAFE is the Aeronautical Information Manual's recommended mnemonic for aircraft pilots to use to assess their fitness to fly.

The mnemonic is:

• Illness - Is the pilot suffering from any illness or symptom of an illness which might affect them in flight?
• Medication - Is the pilot currently taking any drugs (prescription or over-the-counter)?
• Stress - Is the pilot overly worried about other factors in his life? The psychological pressures of everyday living can be a powerful distraction and consequently affect a pilot's performance.
  • The Yerkes-Dodson study illustrates that performance actually improves with increasing levels of stress up to a certain level, then drops off rapidly if the stress level is too great.
• Alcohol - Although legal limits vary by jurisdiction (0.04 BAC, any consumption in the past 8 hours or current impairment in the USA), the pilot should consider their alcohol consumption within the last 8 to 24 hours.
• Fatigue - Has the pilot had sufficient sleep and adequate nutrition?
• Emotion - Has the pilot fully recovered from any extremely upsetting events such as the loss of a family member?

'E', while defined under the FAA as standing for Emotion, is considered by other international Aviation Authorities such as the CAA and CASA to stand for Eating, including ensuring proper hydration, sustenance, and correct nutrition.