In 1981, a late production F-15B (serial number 77-0166) was modified as the test vehicle for the Integrated Flight Fire Control (IFFC)/Firefly III program. The IFFC program was undertaken by McDonnell under a contract from the Air Force for the development of a system which would modify the Eagle's fire control and flight control systems to accept control inputs from both the pilot and the IFFC flight control system and to tailor flight control response to the various weapons delivery modes. The parallel Firefly III program was conducted by General Electric under an Air Force contract for further development of the fire control system for use against air-to-ground targets.
The coupling of IFFC with Firefly III allows for automatic positioning of the aircraft in order to attack targets that are detected by an electro-optical target designation pod. As part of the program, the F-15B carried a Martin Marietta ATLIS (Automatic Tracking Laser Illumination System) II designation pod in the port forward missile well, linked to the aircraft's fly-by-wire system via a computer. The designation pod enabled the aircraft to release air-to-ground weapons while maneuvering along a three-dimensional flight path, avoiding having to fly directly over the target and thus exposing itself to enemy ground fire.
The IFFC/Firefly III system was never adopted for production F-15s. However, the work done on the system was helpful in development of the LANTIRN navigation and targeting system which was adopted for the F-15E Strike Eagle.