The aviation industry continuously evolves, necessitating modifications to existing aircraft designs to enhance performance, efficiency, and safety. Design Organizations play a vital role in this process, undertaking rigorous analyses and testing to ensure compliance with airworthiness requirements. This study focuses on the certification process for TCAS 7.1 Software Updates modification on A320-200 aircraft, considering both TC Holders and Non- TC Holders within the regulatory frameworks of the three civil aviation authorities: FAA, EASA, and DGCA Indonesia. The study aims to highlight the similarities and differences in the certification processes and regulatory requirements of the three authorities. To achieve this, a comparative analysis is conducted, providing concrete examples through simulations of the certification process for the study case. Additionally, the study proposes the development of a user-friendly database research tool to streamline the process of defining the certification basis, specifically for EASA regulation. The research objectives are to elucidate the regulatory variances and develop the database research tool with a user-friendly interface. The scope of work is limited to the specified regulatory frameworks, A320 Family TCDS as a prototype, and EASA TCDS A.064 Issue 51 as the basis for the tool. The methodology involves an extensive literature study, problem statement and research objective development, data collection, database and GUI model development, and comprehensive analysis and discussion of the certification processes. Ultimately, this study contributes to a better understanding of the certification processes among the civil aviation authorities and offers an efficient database research tool to streamline the certification basis definition for regulation.