Begun in FY2008, the SEI’s participation with the Aerospace Vehicle Systems Institute (AVSI) reached a milestone in FY2009, with the successful completion of a proof of concept demonstration of technology for the System Architecture Virtual Integration (SAVI) initiative.

AVSI is a global cooperative of aircraft manufacturers (also called airframers), government organizations, and academic institutions that launched SAVI as an international, industry-wide program to pilot new technology and a new acquisition process based on architectural models rather than paper documentation, with multiple dimensions of analysis used throughout the life cycle, including aircraft virtual integration early in the development process.

SAVI was initiated because airframers know that increasing reliance on embedded software is perhaps the only way to deliver on requirements by airlines for aircraft with greater range and comfort, more seats, and lower seat-mile costs— features that give the airlines more capacity on fewer, more economical flights.

“The current development process is reaching the limit of affordability for building safe aircraft,” notes Peter Feiler of the SEI. “The increase in functionality is supported by embedded software, and its deployment on integrated modular avionics (IMA) platforms that leverage distributed computing has led to a new class of problems not addressed by traditional system development and testing,” Feiler observes.

But airframers see that the cost of developing and testing the software needed is increasing exponentially. Over the past 20 years or so, industry figures imply that the size of aircraft software, measured in source lines of code (SLOC), has doubled every four years. For the next decade, the projected 27.5 million lines of code required are estimated to cost in excess of $10 billion. With more SLOC come greater complexity, for not only does the software need to perform vital dedicated functions such as power distribution or navigation, but also it must deliver a host of critical non-functional qualities, including safety.

“The current development process is reaching the limit of affordability for building safe aircraft,” notes Peter Feiler of the SEI. “The increase in functionality is supported by embedded software, and its deployment on integrated modular avionics (IMA) platforms that leverage distributed computing has led to a new class of problems not addressed by traditional system development and testing,” Feiler observes.

For the SAVI proof of concept (PoC), an aircraft system architecture was modeled using the industry standard Architecture Analysis and Design Language (AADL). A key concept of virtual integration is the use of an annotated architecture model as the single source for analysis; an independent study identified AADL as closely fitting that concept and other needs of the PoC. Also, as part of the PoC demonstration, the AADL architectural model was analyzed using a resource consumption check that is part of the Open Source AADL Tool Environment (OSATE), a toolset made available by the SEI.

Feiler, along with Jörgen Hansson, Lutz Wrage, and SEI resident affiliate Bruce Lewis, headed the SEI’s contribution to the PoC. Over two months, the international PoC team demonstrated the effectiveness of 

• multi-tier modeling and analysis of an aircraft and its subsystems
  
• support for the needs of both system engineers and embedded software system engineers
  
• propagation of changes to the model across multiple analysis dimensions
  
• maintenance of multiple model representations in a model repository 
• auto-generation of analytical models
  
• interfacing of multiple tools 
• distributed team development via a model repository

After the PoC demonstration, the SAVI management team authorized the next three phases of the project, with continuing involvement by the SEI that will take the virtual integration technology to technical readiness level 9, which designates a technology as proven by application.