The software that provides the F-22's avionics system's full functionality is composed of approximately 1.7 million lines of code. Ninety percent of the software is written in Ada, the Department of Defense's common computer language. Exceptions to the Ada requirement are granted only for special processing or maintenance requirements. The software development plan, though stretched as a result of past funding constraints, remained essentially unchanged since the start of Engineering and Manufacturing Development.

Three blocks

The avionics software is integrated in three blocks, each building on the capability of the previous block. Each block cycle is a sequence of subsystem deliveries, integration testing at the Avionics Integration Lab at Boeing and then delivery to Lockheed Martin in Marietta, Ga., for final integration into the aircraft and check out, as well as support to the aircraft.

Block 1 is primarily radar capability, but Block 1 does contain more than 50 percent of the avionics suite's full functionality source lines of code and provides end-to-end capability for the sensor-to-pilot data flow. The fourth F-22 to come out of Engineering and Manufacturing Development will be the first to have a full avionics suite, and it is scheduled to fly in mid-1999. Block 2 is the start of sensor fusion. It adds radio frequency coordination, reconfiguration and some electronic warfare functions.
Block 2 is scheduled to be integrated into the aircraft in late 1999. Block 3 encompasses full sensor fusion built on enhanced electronic warfare functions. It has an embedded training capability and provides for electronic counter-counter measures. It is scheduled to be integrated into the aircraft in the spring of 2000.
Block 3.1, which adds full GBU-32 Joint Direct Attack Munition launch capability and Joint Tactical Information Distribution System receive-only capability, will be integrated in the April of 2000.
The proposed Block 4 software will be post-Engineering and Manufacturing Development. It is scheduled to be integrated on the Initial Operational Capability F-22s and will likely include helmet-mounted cueing, AIM-9X integration, and Joint Tactical Information Distribution System send capability.
Common Integrated Processor (CIP) hardware was available well before the subsystem application software code and unit test phases began for the Block 1 software.
The Block 1 system test tools, including simulations of the subsystems, non-avionics aircraft systems, and external environment, are on schedule for Block 1 integration. For some of the higher risk software, such as sensor data fusion, specific algorithm testbeds have been constructed, and prototype software, which is instrumented to measure performance (correlation times, accuracy, etc.). has been operational since the start of Engineering and Manufacturing Development.