What is the common designation for operations at O'Hare Airport?

The designation "ORD" refers to O'Hare International Airport and is widely recognized as the airport code for this location. This code is part of the International Civil Aviation Organization (ICAO) and the International Air Transport Association (IATA) coding systems, which assign unique identifiers to airports worldwide. Using a standardized code like ORD helps streamline communication and logistics in aviation, ensuring that pilots, air traffic controllers, and ground staff all refer to the same place without confusion.

In contrast, the other options presented do not conform to the established airport coding conventions. “ORDC” and “OHR” do not represent any recognized identifiers for O'Hare, while "OHARE," while it may signify the airport's name, does not follow the coding structure that is universally accepted. Therefore, "ORD" is the appropriate and correct choice for referring to O'Hare International Airport.