Speaking in general terms, the software load on a 5th generation jet has much to do. It must tie multiple systems together into a coherent whole. An incomplete

Speaking in general terms, the software load on a 5th generation jet has much to do. It must tie multiple systems together into a coherent whole. An incomplete list of what the software must do includes: 1) Provide basic flight control services through the control laws that transform pilot intent into commands to individual flight control surfaces 2) Basic and advanced navigation (GPS, TACAN) 3) Sensor fusion. Taking in data streams from multiple types of sensors and presenting a coherent picture to the pilot of the space surrounding the aircraft, notifying the pilot of dangers and target opportunities 4) Stores management. Keeping track of the ordnance loaded on each station of the aircraft so that the flight control system can compensate as weapons are launched. Communicating with active weapons so that they have the necessary targeting information. 5) Electronic warfare, jamming, and countermeasures. 6) Operational mission plan. Fans of the old Microprose flight sims would recognize this as a set of instructions that tell the jet something like -- 1) Takeoff from Sicily 2) Destroy missile boat 3) Destroy SAM Radar at Benghazi...etc. 7) Data links to other aircraft, satellites, and ground systems. 8) Provide interfaces for future system growth and improvement. You can see that there are a vast array of data interfaces that must be managed with all kinds of operational and time constraints. Writing and testing all of this code does take much time and effort.