SAFE-P: System for Assurance of Flight Executable Procedures, Phase I

Problem: Ensuring that command execution scripts do not deviate from Standard Operating Procedures (SOPs) is time-consuming, costly, and error-prone. Deviations can be inefficient or hazardous. Solution: We propose to design and develop SAFE-P, an interactive tool to ensure conformance between command scripts and procedures, or guide users to clarify their rationale for deviations. Using semantic differencing and formal verification of bisimulation relations, SAFE-P will ensure that the scripts comply with SOPs and will highlight differences for the operators, so that they can double-check their work and confirm any deviations from standard procedures. SAFE-P's design will begin with relatively simple syntactic mechanisms to find differences between command sequences and textual procedures that can be applied directly to current flight control practices, including the use of SOPs captured in simple XML or PDF files and command scripts in ThinLayer. To reduce false error detection and assess the criticality of differences, we will incorporate knowledge of the space platform's architecture. For future missions, we will extend SAFE-P to richer languages (PRL, PLEXIL, SCL) and employ more complex verification of program-equivalence relationships (bisimulation) to ensure conformance between scripts and procedures. More »