Safety In Numbers, or At Least DO-178B

There's something about the term "safety-critical systems" that makes you stop and think, especially at that moment when the wheels leave the ground. Fortunately I'm among those lucky people who fall asleep (yes, head back, mouth open) as soon as the the airplane leaves the terminal, and the only thing I worry about is snoring too loudly.

Still, because I tend to fly more than drive these days (driving to the airport doesn't count), anything involving avionics wakes me up. Which is why DO-178B caught my attention. Granted, if you've been involved in avionic software or real-time systems, DO-178B is probably is old hat. In a nutshell, DO-178B identifies guidelines and certification for the development of aviation software in the U.S.

What got me thinking about safety-critical issues and introduced to me DO-178B was conversations at this week's Dr. Dobb's SD Best Practices Conference in Boston. It's no surprise, for instance, that Ada has long been a mainstay in large-scale high-reliability, safety-critical arenas. To that end, in support of DO-178B and other such safety standards, AdaCore announced a static analysis tool called GNATstack that helps engineers predict the maximum stack usage requirements for applications. The tool statically caluculates the maximum stack space required by each task in an application. The coputed bounds can be used to ensure that sufficient space is reserved, thus ensuring safe predictable execution in regards to stack usage. The tool's output data can then be used to satisfy DO-178B requirements. Putting this another, stack overflow is bad enough at any time, but really bad at 20,000 feet up.

LynuxWorks also made some announcements regarding safety-critical systems for the avionics industry. In particular, the company said it is working with TTTech Computertechnik AG, a supplier of solutions in the field of "time-triggered technologies," to build tools for the migration of prototype safety-critical avionics applications to full airborne deployment. TTTech’s TTP protocol is supposedly the first high-speed, time-triggered fieldbus selected for commercial and military aircraft, such as the Boeing 787, Airbus A380 and Lockheed Martin F-16. TTP systems can be built using TTTech’s design tools deployed in production programs. Available embedded COTS software and hardware components are compliant to DO-178B and can be reconfigured for reuse in different distributed real-time systems.

Like I said: I'm lucky that I can sleep on airplanes and not have to worry about safety issues. It looks like plenty of other people are doing the worrying for me.

Posted by Jon Erickson at 09:39 AM  Permalink