So SAE ARP and SAE ARP go hand in hand and use functional approach to safety. Both ARPS focused on complex aircraft systems development . A Comparison of STPA and the ARP Safety. Assessment Process. 1. MIT PSAS Technical Report. 2 Rev. 1. 3. Nancy Leveson, MIT. Chris Wilkinson. The ARP document describes guidelines and methods of performing the safety assessment for certification of civil aircraft. It is primarily associated with.