In an integrated change management project, human factors and functional safety cannot be considered separately. Both must work closely together to provide appropriate and comprehensive assurance for the introduction of complex changes to safety critical industries. This paper presents case studies of two different projects where safety and human factors were joined up in a coherent set of activities across all project phases. The first project looks at the UK airspace de-sign changes to air traffic management in preparation for the London 2012 Olympics. The second examines the introduction of an advanced set of controller tools (iFACTS), introduced at the Swanwick London Area Control Centre in 2011. Both case studies represent examples of effective integration of safety and human factors assurance activities.