Avionics systems are becoming more powerful and more dependent upon data exchanged between instruments. These instruments and subsystems reside on a network and must share time-critical data to achieve their mission. For example, targeting systems require real-time input of aircraft speed and attitude, as well as position and velocity data of the target. At the same time, additional bandwidth is required for data from onboard systems, such as GPS, airspeed and directional gyro, flight control systems, and dozens of other instruments and subsystems. As a result, network traffic is high, and potential data interactions can be highly complex. This complexity makes real-time integration of the data from disparate instruments during operational missions a significant challenge. Furthermore, upgrades of avionics and software applications during the useful life of the airframe means that new subsystems must be seamlessly integrated with legacy subsystems. In other words, data paths, interactions, and integration are not fixed forever. Today, aircraft systems typically are constructed to provide point-to-point communications between instruments and control systems that require realtime data. This approach has a significant impact on the complexity of the system and its subsequent maintainability. If an instrument is upgraded or replaced, the interfaces between it and other directly connected devices have the potential to change, requiring significant recoding and retesting.
Correct upfront design choices can minimize the technical issues and complexity of integrating time-critical data from disparate avionics systems and enable those systems to make decisions based on that data. A proven method is to use a design architecture based on a standards-based commercial RTOS and data distribution middleware that abstracts the need for specific knowledge about the devices generating or consuming data. Such a solution can ensure timely delivery of data across an avionics network, no matter what specific instruments are present on that network An RTOS that employs the POSIX (Portable Operating System Interface) standard provides a known and published application interface that can support changes in applications, instruments, and even the RTOS itself. Full POSIX conformance ensures that applications can be easily ported between conforming operating systems, making it possible to upgrade or change code without major changes and extensive testing to the application. Further, an RTOS that conforms to the POSIX standard can also be tested and certified according to the rigorous requirements of the POSIX standard, as defined by The Open Group, proving full API support and the most portability for customers. Avionics system integrators can have confidence in the integrity, performance, reliability, and flexibility of their software.