What medical condition can lead to unfitness for flying?

Severe cardiac disease can significantly impair a person's ability to fly safely. This condition can lead to a range of complications, such as arrhythmias, myocardial infarction (heart attack), and decreased exercise tolerance, which can become critical in the demanding environment of aviation. The stressors associated with flying—such as changes in altitude, physiological stress, and the need for rapid decision-making—can exacerbate cardiac issues, potentially leading to incapacitation during flight. Therefore, pilots or aircrew members diagnosed with severe cardiac disease are generally considered unfit for flying duties due to the increased risk of acute episodes that could compromise safety for themselves, their passengers, and other aircraft.