In India, National Board of Accreditation (NBA) has been mandated with the quality assessments and accreditation of engineering programs. NBA has introduced the accreditation system based on Outcome Based Education (OBE) with paradigms like program educational objectives (PEOs), program outcomes (POs), course outcomes (COs), assessments, continuous improvements etc. A sustainable assessment methodology based on students' feedbacks on course outcomes has been adopted and implemented in an engineering institute. Based on the assessments of COs and COs vs POs mapping, attainments of POs were arrived. Further, the COs attainments are validated against the University Results. Assessments are repeated every semester, leading towards periodic assessments of COs and POs. The process was found to be sustainable and achieved continuous quality improvements across all programs, when implemented.