Final answer:
The airframe includes structural elements of an airplane like wings and fuselage, excluding engine and avionics. Advances in aviation have led to more reliable engines, better materials, and sophisticated electronic systems.
Step-by-step explanation:
The airframe of an airplane refers to all the components that make up the plane, excluding the engine and avionics (electronic systems used on the aircraft, such as communication and navigation systems). When one refers to the airframe, they are specifically talking about the structural elements such as the wings, fuselage, tail, and landing gear. The development of airplanes has seen significant advancements over the years, with major innovations being the introduction of reliable and powerful engines, the use of new construction materials, and the evolution of electronic instrumentation and actuators, which have dramatically improved air travel safety and efficiency.