Aerospace Recommended Practice (ARP) 4754 Revision A (ARP4754A), “Guidelines for Development of Civil Aircraft and Systems,”  is recognized through Advisory Circular (AC) 20-174 (AC 20-174)  as a way (but not the only way) to provide development assurance for aircraft and systems to minimize the possibility of development errors. ARP4754A and its companion, Aerospace Information Report (AIR) 6110, “Contiguous Aircraft/System Development Process Example,”  primarily describe development processes for an all new, complex and highly integrated aircraft without strong consideration for reused systems or simple systems. While ARP4754A section 5 mentions reuse, similarity, and complexity, and section 6 is intended to cover modification programs, the descriptions in these sections can be unclear and inconsistent.The majority of aircraft projects are not completely new Products nor are they entirely comprised of complex and highly integrated systems. Due to the lack of focus of ARP4754A on these conventional types of projects, planning for the use of the ARP4754A processes becomes difficult. Further complicating such planning is a redundancy with conventional systems certification, which processes such DO-178C  and DO-254  do not face. Regulatory guidance involving ARP4754A (i.e., AC20-174, AC23-1309-1C , Part 23 ARC , and Order 8110.4C ) can also be vague and in some cases conflict.This work describes a recommended methodology for properly scoping the application of ARP4754A for an aircraft project with new complex and highly integrated systems along with reused and simple systems. This planning methodology can also be applied on modification projects allowing for “traditional techniques” where applicable. This work also provides a path forward for potential changes to sections 5 and 6 in the next revision of ARP4754 to provide clarity and consistency.