What is defined as Airfield in airport terminology?

The term "Airfield" in airport terminology refers specifically to a part of the Airport Operations Area (AOA) that is designated for aircraft operations. This includes runways, taxiways, and other surfaces necessary for the movement of aircraft during takeoff, landing, and ground operations. Understanding this definition is critical for aviation professionals, as it relates directly to aircraft safety, operations management, and airport design.

The other options are distinct aspects of airport functionality but do not accurately capture the definition of "Airfield." Administrative offices are typically located in terminal buildings but have no direct role in the operational aspects for aircraft. A passenger boarding area pertains to the terminal facilities for passenger processing rather than the physical area where aircraft operate. The customs and immigration zone deals with the processing of passengers and goods entering a country, which is separate from the operation of aircraft on the airfield.