Section 47. The public safety requiring, and the advantages of uniform regulation making it desirable in the interest of aeronautical progress, that a person engaging within this commonwealth in navigating or operating aircraft in any form of navigation should have the qualifications necessary for obtaining and holding a pilot's license, permit or certificate, issued by the Civil Aeronautics Authority of the United States or other proper licensing authority, no person shall operate or navigate any aircraft in this commonwealth unless such person is the holder of an appropriate effective pilot's license, permit or certificate, issued by said authority; provided, that this restriction shall not apply to persons operating military aircraft of the United States or possessions thereof, public aircraft of any state or territory, or any aircraft licensed by a foreign country with which the United States has a reciprocal agreement covering the operation of such licensed aircraft, nor to glider pilots licensed by the commission in accordance with such regulations as it may prescribe, nor to persons operating model aircraft, nor to any person piloting an aircraft which is equipped with fully functioning dual controls when a certificated instructor is in full charge of one set of said controls and such flight is solely for instruction or for the demonstration of said aircraft to a bona fide prospective purchaser thereof, nor to qualified airmen operating an aircraft on the ground at an airport, except on a landing area.