Which condition is NOT a disqualifying factor for a first class medical certificate?

The condition that is not a disqualifying factor for a first class medical certificate is correctable eyesight. According to FAA regulations, individuals with correctable vision issues can still qualify for a medical certificate as long as their vision can be improved to meet the required standards through the use of glasses or contact lenses. This flexibility acknowledges that many pilots may need visual aids to achieve the necessary level of acuity for safe flying.

In contrast, loss of consciousness, epilepsy, and loss of nervous system functions are serious medical conditions that can significantly impair a person's ability to operate aircraft safely. These conditions typically lead to disqualification because they may present an ongoing risk of incapacitation, a critical concern for maintaining safety in aviation. Thus, correctable eyesight stands out as a condition where intervention (like corrective lenses) can restore necessary function without eliminating an individual's ability to be certified as a first-class pilot.