Integrated modular avionics
Integrated modular avionics (IMA) are real-time computer network airborne systems. This network consists of a number of computing modules capable of supporting numerous applications of differing criticality levels.
The IMA concept proposes an integrated architecture with application software portable across an assembly of common hardware modules. An IMA architecture imposes multiple requirements on the underlying operating system.
It is believed that the IMA concept originated with the avionics design of the fourth-generation jet fighters. It has been in use in fighters such as F-22 and F-35, or Dassault Rafale since the beginning of the '90s. Standardization efforts were ongoing at this time (see ASAAC or STANAG 4626), but no final documents were issued then.
First uses for this concept were in development for business jets and regional jets at the end of the 1990s and were seen flying at the beginning of the 2000s, but it had not been yet standardized.[not in citation given]
IMA modularity simplifies the development process of avionics software:
- As the structure of the modules network is unified, it is mandatory to use a common API to access the hardware and network resources, thus simplifying the hardware and software integration.
- IMA concept also allows the Application developers to focus on the Application layer, reducing the risk of faults in the lower-level software layers.
- As modules often share an extensive part of their hardware and lower-level software architecture, maintenance of the modules is easier than with previous specific architectures.
- Applications can be reconfigured on spare modules if the primary module that supports them is detected faulty during operations, increasing the overall availability of the avionics functions.
However, much complexity is added to the systems, which thus require novel design and verification approaches since applications with different criticality levels share hardware and software resources such as CPU and network schedules, memory, inputs and outputs. Partitioning is generally used in order to help segregate mixed criticality applications and thus ease the verification process.
ARINC 650 and ARINC 651 provide general purpose hardware and software standards used in an IMA architecture. However, parts of the API involved in an IMA network has been standardized, such as:
- ARINC 653 for the software avionics partitioning constraints to the underlying Real-time operating system (RTOS), and the associated API
RTCA DO-178C and RTCA DO-254 form the basis for flight certification today, while DO-297 gives specific guidance for Integrated modular avionics. ARINC 653 contributes by providing a framework that enables each software building block (called a partition) of the overall Integrated modular avionics to be tested, validated, and qualified independently (up to a certain measure) by its supplier.
Examples of IMA architecture
Examples of aircraft avionics that uses IMA architecture :
- Airbus A350
- Airbus A380 
- Airbus A400M
- ATR 42
- ATR 72
- BAE Hawk (Hawk 128 AJT)
- Boeing 777 : includes AIMS avionics from Honeywell Aerospace
- Boeing 787 : GE Aviation Systems (formerly Smiths Aerospace) IMA architecture is called Common Core System 
- Boeing 777X: will include the Common Core System from GE Aviation
- Bombardier Global 5000 / 6000 : Rockwell Collins Pro Line Fusion
- Dassault Falcon 900, Falcon 2000, and Falcon 7X : Honeywell's IMA architecture is called MAU (Modular Avionics Units), and the overall platform is called EASy
- F-22 Raptor
- Gulfstream G280: Rockwell Collins Pro Line Fusion
- Rafale : Thales IMA architecture is called MDPU (Modular Data Processing Unit) 
- Sukhoi Superjet 100
- COMAC C919
- Annex: Acronyms and abbreviations in avionics
- OSI model
- Cockpit display system
- ARINC 653 : a standard API for avionics applications
- Def Stan 00-74 : ASAAC standard for IMA Systems Software
- STANAG 4626
- "ASSC - Evaluation of RTOS Systems" (PDF). assconline.co.uk. March 1997. Archived from the original (PDF) on 2011-09-04. Retrieved 2008-07-27.
- "Integrated Modular Avionics: Less is More". Aviation Today. 2007-02-01.
Some believe the IMA concept originated in the United States with the new F-22 and F-35 fighters and then migrated to the commercial jetliner arena. Others say the modular avionics concept, with less integration, has been used in business jets and regional airliners since the late 1980s or early 90s
- "Technical hurdles delay Primus Epic program". ainonline.com. 2003-08-01. Archived from the original on 2010-07-16. Retrieved 2008-09-27.
When Honeywell started the development program no one had ever certified an MAU. There were no regulations or TSO standards to follow and so Honeywell had to start from square one, working with the FAA and JAA to set the standards for what an MAU would be.
- René L.C. Eveleens (2 November 2006). "Integrated Modular Avionics - Development Guidance and Certification Considerations" (PDF). National Aerospace Laboratory. Archived from the original (PDF) on 2012-06-03. Retrieved 2011-06-25.
Biggest challenge within this area is that modular avionics is a composition of building blocks, preferably supplied by different companies in the supply chain. Each supplier is supposed to bring its part to a certain level of qualification, and after this a system integrator can use these “pre-qualified” part in the overall certification process.
- "Avionics for the A380: new and highly functional ! Dynamic flightdeck presentation at Paris Air Show". Thales Group. 2003-06-17. Archived from the original on 2008-05-03. Retrieved 2008-02-09.
Integrated Modular Avionics (IMA), based on standardised modules that can be shared by several functions. The IMA concept is very scalable, and delivers significant improvements in reliability, maintainability, size and weight.
- "Common Core System (CCS)". GE Aviation Systems. Retrieved 2008-02-09.
GE has developed a compute platform running an ARINC 653 partitioned operating environment with an Avionics Full Duplex Switched Ethernet (AFDX) network backbone. The CCS provides shared system platform resources to host airplane functional systems such as Avionics, Environmental Control, Electrical, Mechanical, Hydraulic, Auxiliary Power Unit, Cabin Services, Flight Controls, Health Management, Fuel, Payloads, and Propulsion.
- "Dassault Falcon EASY Flight Deck". Honeywell. July 2005. Retrieved 2008-02-09.
The heart of the EASy platform is two, dual-channel, cabinet-based modular avionics units (MAUs). Highly rationalized, the MAU integrates functional cards for several applications into a single module. Each functional card performs multiple tasks previously requiring dedicated computer processors.
- "Thales wins major Rafale through-life support contract from SIMMAD". Thales Group. Archived from the original on 2008-05-03. Retrieved 2008-02-09.
- "RAFALE". Dassault Aviation. 2005-06-12. Archived from the original on 2007-12-04. Retrieved 2008-02-09.
The core of the enhanced capabilities of the RAFALE lies in a new Modular Data Processing Unit (MDPU). It is composed of up to 18 flight line-replaceable modules, each with a processing power 50 times higher than that of the 2084 XRI type computer fitted on the early versions of Mirage 2000-5.
IMA Publications & Whitepapers
- "Transitioning from Federated Avionics Architectures to Integrated Modular Avionics", Christopher B. Watkins, Randy Walter, 26th Digital Avionics Systems Conference (DASC), Dallas, Texas, October 2007.
- "Advancing Open Standards in Integrated Modular Avionics: An Industry Analysis", Justin Littlefield-Lawwill, Ramanathan Viswanathan, 26th Digital Avionics Systems Conference (DASC), Dallas, Texas, October 2007.
- "Application of a Civil Integrated Modular Architecture to Military Transport Aircraft", R. Ramaker, W. Krug, W. Phebus, 26th Digital Avionics Systems Conference (DASC), Dallas, Texas, October 2007.
- "Integrating Modular Avionics: A New Role Emerges", Richard Garside, Joe F. Pighetti, 26th Digital Avionics Systems Conference (DASC), Dallas, Texas, October 2007.
- "Integrated Modular Avionics: Managing the Allocation of Shared Intersystem Resources", Christopher B. Watkins, 25th Digital Avionics Systems Conference (DASC), Portland, Oregon, October 2006.
- "Modular Verification: Testing a Subset of Integrated Modular Avionics in Isolation", Christopher B. Watkins, 25th Digital Avionics Systems Conference (DASC), Portland, Oregon, October 2006.
- "Certification Concerns with Integrated Modular Avionics (IMA) Projects", J. Lewis, L. Rierson, 22nd Digital Avionics Systems Conference (DASC), October 2003.