game's airspace with up to 600 artificially intelligent (AI) planes, which fly and respond to the player in real-time. Real-time air traffic control (ATC) directs the player and the AI planes to prevent collisions. The player interacts with the ATC and with other planes by constructing radio messages with a menu. Three cockpit views are available: IFR (instrument flight rules), which allows the player to monitor and interact with all flight instruments; VFR (visual flight rules), which features a larger windshield area but fewer flight instruments; and Virtual Cockpit View, which allows free look but features no interactive flight instruments. External camera angles are also available, and the player may ride as a passenger in any AI plane. Development Following the completion of Flight Unlimited in 1995, project leader Seamus Blackley planned to use that game's computational fluid dynamics (CFDs) code to create a combat flight simulator called Flight Combat. However, a new manager at Looking Glass Studios demanded that Blackley instead design a direct sequel to Flight Unlimited. Blackley refused and was fired, leaving the company in late 1995. Constantine Hantzopoulos became the lead designer and project leader of the fourteen-member Flight Unlimited II team. The team eschewed the aerobatics focus of their previous game in favor of general civilian aviation, in order to compete with the Microsoft Flight Simulator series. Looking Glass announced the game on December 18, 1996. It was slated to include 6 planes, 45 airports and 8,500 square miles of terrain from the San Francisco Bay Area. The Bay Area was chosen because of its varied landscape and numerous airports. In January 1997, Eidos Interactive partnered with Looking Glass to provide the game's marketing and distribution. The team opted not to reuse the technology of Flight Unlimited. Hantzopoulos learned from Blackley that it was necessary to recreate the "visceral feel" of real flight, but Blackley's CFDs system was "all black box spaghetti code" that the team could not understand. Programmer Jim Berry, who had previously worked on simulators such as Falcon 4.0, wrote new physics code based on force vector calculations to replace the CFDs system. To gather data for the new physics, Hantzopoulos and Berry flew in real-world planes with designer Ed Tatro and aerobatic pilot Michael Goulian. James Fleming coded Flight Unlimited IIs new terrain renderer, ZOAR. Flight Unlimited uses distance fog to limit visible terrain, but this causes pop-in issues that the