Flight Simulator 2004 or FS 2004 is officially known as Microsoft Flight Simulator 2004: A Century of Flight. Microsoft Flight Simulator 2004: A Century of Flight was released in 2003 to commemorate the 100th anniversary of Wright Brothers' first flight. FS 2004 is also known as FS9. The AI flight plans for FS 2004 or FS9 are known as fs9 ai flight plans.

The fs9 ai flight plans allow aviation enthusiasts and hobbyists to experience flying several historical aircraft. The fs9 ai flight plans include historical aircraft such as the Wright Flyer, Ford Tri-Motor, Charles Lindbergh's Ryan NYP “Spirit of St. Louis,” and the Douglas DC-3 to commemorate the centenary of Wright Brothers' first flight.

The fs9 ai flight plans feature interactive multimedia providing rich historical information on the planes that shaped aviation history and the pilots who flew them. The fs9 ai flight plans include informed and insightful articles that explain the 24 aircraft included in the software. The fs9 ai flight plans also feature updated-dynamic weather system, enhanced automatically generated scenery (AutoGen) and detailed visual effects, improved Air Traffic Control functions, and 3D interactive cockpits, as well as 15 modern aircraft, including the Beechcraft Baron and the Robinson R22 helicopter.

FS 2004 offers a wide range of fs9 ai flight plans and packages. The fleet for fs9 ai flight plans also include the aircraft that are part of each version of Microsoft Flight Simulators, which include Aérospatiale-BAC Concorde, Airbus A321, Air Creation Trike Ultralight 582 SL, Beechcraft Baron 58, Beechcraft Baron 58 G1000, Beechcraft King Air 350, Bell 206B JetRanger, Boeing 737-400, Boeing 737-800, Boeing 747-400, Boeing 777-300, Bombardier CRJ 700, Bombardier Learjet 25G, Bombardier Learjet 35A, Bombardier Learjet 45, Cessna C208 Caravan Amphibian, Cessna C208B Grand Caravan, Cessna C172SP Skyhawk, Cessna C172SP Skyhawk G1000, Cessna C182S Skylane, Cessna C182RG Skylane, Curtiss Jenny, de Havilland Dash 8-100, de Havilland Canada DHC-2 Beaver Floatplane, de Havilland DH-88 Comet, DG 808S 18 Meter Sailplane, Douglas DC-3, Extra 300S, Ford 4-AT-E Tri-Motor, Grumman G-21A Goose, Lockheed Vega, Maule Orion M-7-260C Ski, Maule Orion M-7-260C Super Rocket, McDonnell-Douglas/Boeing MD-83, Mooney Bravo, Mooney Bravo G1000, Piper Cherokee 180, Piper J-3 Cub, Robinson R22 Beta II, Schweizer 2-32 Sailplane, Sopwith Camel, Ryan NYP “Spirit of St. Louis”, Vickers Vimy, and Wright Flyer.

The system requirements for fs9 ai flight plans include Microsoft® Windows® 98/Me/XP/2000, PC with 450 MHz equivalent or higher processor, 28 MB of system RAM for 2000/XP, 64 MB RAM for 98/Me, 1.8 GB available hard disk space, 4x speed or faster CD-ROM drive, 8 MB video card, Sound card, speakers or headphones, Microsoft Mouse or compatible pointing device, 56.6 Kbps or better modem for online play. There is a wide variety of fs9 ai flight plans available online that can be downloaded and enjoyed.