From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.5-pre1 (2020-06-20) on ip-172-31-74-118.ec2.internal X-Spam-Level: X-Spam-Status: No, score=-0.9 required=3.0 tests=BAYES_00,FROM_ADDR_WS autolearn=no autolearn_force=no version=3.4.5-pre1 Date: 19 Aug 93 16:45:00 GMT From: skates.gsfc.nasa.gov!bambam.gsfc.nasa.gov!nbssal@ames.arc.nasa.gov (Step he Leake) Subject: Re: Sweden Fighter Crash Message-ID: <19AUG199311451826@bambam.gsfc.nasa.gov> List-Id: In article <26347@alice.att.com>, peju@alice.att.com (Peter Juhl) writes... > >Last week Bjarne Stroustrup posted something about the fighter >that crashed in Sweden. Eventhough his main point was about >the difficulty of comparing languages, and the traps that people >fall into when they do so, there was some follow-ups about the >crash as such. > >Somebody from Sweden expressed doubts about Bjarne knowing anything about >what caused the failure, which Bjarne attributed to software. > >This just came in on the apnews > > STOCKHOLM, Sweden (AP) _ Sweden's new jet fighter crashed during >an air show last week because of a computer flaw, an inquiry board >said Wednesday in clearing the pilot of blame. > Producers and military officials had been aware that vigorous >movement of the control stick could cause the JAS 39 Gripen to go >out of control because of computer overcompensation. But they >underestimated the problem, the government board said in a >preliminary report. > >[ ... stuff deleted ... ] > This sounds more like a bad value for a gain parameter, causing the control system to go unstable, rather than a flaw in the program or compiler. I work with real-time control systems; there are many things that can go wrong even after the compiler and algorithm bugs are all found! If it is a bad gain, then it is the control engineers, not the software enginee rs, who are at fault. Let's not assume everything is a software fault just because we are software people! Stephen Leake NASA Goddard Robotics Lab internet : nbssal@robots.gsfc.nasa.gov