Does anyone know what it&#x27;s written in?<p>Boeing writes (nearly) everything in Ada and as far as I know has never had any software problems of this scale. Most of it is in SPARK as well, a restricted subset of Ada that can be partially formally verified[1]. Frankly, <i>not</i> formally verifying mission-critical software where a failure can potentially threaten someone&#x27;s life seems rather irresponsible.<p>1. Contrary to what seems popular opinion, regular Ada is not particularly strict (less so than Rust). SPARK is very, very strict about what you can compile, and if it compiles it follows the spec (which is usually easier to audit).