According to RA 9497, how is an aircraft defined?

The definition of an aircraft under Republic Act No. 9497 includes the specific criteria that an aircraft is any machine that can derive support in the atmosphere from the reactions of the air. This definition highlights the fundamental principle of flight, which is the interaction between the aircraft and the atmosphere, particularly the lift generated by air flowing around the structure of the aircraft.

This definition is essential because it encompasses a broad range of vehicles that can achieve flight through various means, not limited solely to engines or propulsion systems. By focusing on the concept of deriving support from air reactions, it includes not just conventional fixed-wing aircraft but also lighter-than-air vehicles, gliders, and other types of flying machines that may not rely on traditional engines for their flight capabilities.

The other choices narrow the definition in ways that exclude certain types of aircraft or provide definitions that are too vague or incomplete. For example, stating that it is merely any machine that flies does not consider the mechanics of how lift is achieved. Similarly, mentioning engines diminishes the diversity of aircraft that can operate without engine power, such as gliders or balloons. The key aspect of the correct definition emphasizes the aerodynamic principles rather than simply the presence of an engine.