"Helicopter Ride" was a planned campaign mission in Call of Duty 4: Modern Warfare. All that proves its existence is a file called "compass_map_helicopter_ride" present in the game's source files. Additionally, a vision file called helicopter_ride.vision was found in the game's source files.
The minimap for the mission is mostly unedited, save for a quick de-saturation to rid the minimap of color. The mission's helicopter's starting point is defined, as well as the path it takes. In the bottom right-hand corner, the text "CoD3 1.0 build 10047 Wed Dec 20 17:5" can be made out, meaning this level existed 11 months before the game's release.