On his website, aviation safety expert witness John Ogle, MD, MPH, FACEP, answers frequently asked questions about being an aviation medical examiner:
What is an Aviation Medical Examiner and how does one become designated?
Under the Federal Aviation Act of 1958 (as amended), the FAA Administrator is authorized to delegate to qualified private physicians the conduct of medical examinations and the issuance of medical certificates to qualified applicants. Aviation Medical Examiners (AMEs) are private physicians, trained and authorized by the FAA to perform airman medical examinations, and to issue medical certificates. New AMEs are designated based upon the local demand for aeromedcial certification services.