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Integrated modular avionics

technology Maturity 11-13 Next article →

Integrated Modular Avionics, or IMA, is a real-time computer network system used in aircraft. This technology represents a major shift in how airplanes manage their electronic systems. Instead of using many separate, dedicated boxes for every single task, IMA uses a group of computing modules. These modules work together as a unified network to support many different applications. These applications can have different levels of criticality, which means some tasks are more vital to flight than others. IMA is essential because it makes aircraft more efficient, easier to maintain, and more reliable during flight.

To understand how IMA works, we must look at its modular architecture. In older systems, each function had its own specific hardware. In an IMA system, software is portable across an assembly of common hardware modules. This means the software is not stuck to one specific piece of equipment. The modules share many resources, such as the central processing unit (CPU), memory, and input/output systems. To make this work, the system uses a common Application Programming Interface (API). This API acts like a universal translator, allowing different software to access the hardware and network resources in a standard way.

Because these modules share so much hardware, the system uses a process called partitioning. Partitioning is a method used to segregate applications with different criticality levels. This ensures that a less important task does not interfere with a critical flight function. By using partitions, engineers can manage how the CPU, memory, and network schedules are shared. This structure also allows for high availability. If the primary module supporting an application is detected as faulty during operations, the application can be reconfigured on a spare module.

The history of IMA is closely tied to the evolution of military aviation. It is believed that the IMA concept originated with the design of fourth-generation jet fighters. Since the beginning of the 1990s, this technology has been used in advanced fighters like the F-22 Raptor and the F-35. The Dassault Rafale also utilizes these principles. During the early development of these systems, engineers worked on standardization efforts. These included early efforts like ASAAC and STANAG 4626, though final documents were not issued during that specific era.

Standardization is vital for the safety and certification of these complex systems. Several technical standards govern how IMA operates. For example, ARINC 653 is a standard API that manages software partitioning constraints within the Real-time Operating System (RTOS). This framework allows each software building block, known as a partition, to be tested and validated independently by its supplier. For flight certification, engineers rely on RTCA DO-178C and RTCA DO-254. Additionally, DO-297 provides specific guidance for Integrated Modular Avionics. Communication between modules can happen through an internal high-speed computer bus or external networks like ARINC 429 and ARINC 664.

Many modern commercial and military aircraft rely on IMA architecture today. In the Boeing family, the 777 uses the AIMS avionics from Honeywell Aerospace. The 777X will feature the Common Core System from GE Aviation, while the 787 uses a similar system also called the Common Core System. Airbus aircraft, such as the A220, A350, A380, and the A400M, all utilize IMA. Other notable examples include the Bombardier Global 5000 and 6000, which use Rockwell Collins Pro Line Fusion. The Dassault Falcon series uses Honeywell's Modular Avionics Units, or MAU, within its EASy platform.

The variety of implementations shows how central this technology has become. For instance, the Sukhoi Superjet 100 and the COMAC C919 also use these architectures. Even smaller aircraft, like the ATR 42 and ATR 72, benefit from this modularity. By moving away from federated architectures, the aviation industry has gained a way to simplify software development. Developers can focus on the application layer rather than low-level software. This reduces the risk of faults and makes maintaining the modules much easier than it was with older, specific architectures.

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