Pteromerhanophobia is a fear of being on an airplane (aeroplane), or other flying vehicle, such as a helicopter, while in flight. It is also sometimes referred to as aerophobia, aviatophobia, aviophobia or fear of flying in common speech.

Fear of flying may be a distinct phobia in itself, or it may be an indirect combination of one or more other phobias related to flying, such as claustrophobia (a fear of enclosed spaces) or acrophobia (a fear of heights). It may have other causes as well, such as agoraphobia (especially the type that has to do with fear of open spaces). It is a symptom rather than a disease, and different causes may bring it about in different individuals.

The fear receives more attention than most other phobias because air travel is often difficult for people to avoid—especially in professional contexts—and because the fear is widespread, affecting a significant minority of the population. A fear of flying may prevent a person from going on vacations or visiting family and friends, and it can cripple the career of a businessperson by preventing them from traveling on work-related business.