Abstract

INTRODUCTION

Fitness to fly is not defined merely by the absence of disease. The standards for aircrew are such that even without significant disease an individual may not be considered fit to fly, for example if there is significant myopia. In contrast, even documented conditions, such as coronary artery disease, may not preclude fitness to fly in certain circumstances. The medical standards are set with the aim of maintaining flight safety at an acceptable level.

WHAT IS AN ACCEPTABLE RISK?

A zero risk environment is unattainable. In aviation therefore the concept of ‘acceptable risk’ has been developed (Tunstall-Pedoe 1984). This approach uses an overall fatal accident rate which is reasonably achievable (one in 10 million flights). To simplify the calculations which follow, each flight is deemed to last 1 hour, though most commercial flights are much longer. It is further postulated that no one component (crew failure, airworthiness, mechanical failure