The Indonesian Aviation Industry has become a primary need and has become a strategic industry. In 2019, the issue of soaring airfares was highlighted by several domestic airlines. This certainly raises suspicions about cartel practices in the Indonesian aviation industry. In business practices in Indonesia, businesses often Conduct unhealthy competition through horizontal, vertical or through certain business behaviors. One of the business behaviors that can harm workable competition in the market or industry is the Oligopoly. Therefore, the study of the alleged occurrence of cartels in the domestic flight industry in Indonesia is written. This study is written based on two formulations. The first is that the pricing of domestic flight tickets made by the two dominant airlines in Indonesia can be categorized as a cartel according to Law No. 5 of 1999 on Prohibition of Monopoly Practices and Unfair Business Competition. Second, How the efforts of the government and the Business Competition Supervisory Commission ("KPPU") in overcoming cartel practices by two domestic airlines within the framework of enforcement of Law No. 5 of 1999 on Prohibition of Monopoly Practices and Unfair Business Competition. Based on the results of the decision issued by KPPU through a verdict with case number 15/KPPU-I/2019 KPPU cannot prove that cartel activities occurred in the domestic aviation industry. KPPU's inability to prove cartel activities in this industry is suspected due to the lack of detailed guidelines on the application of indirect evidence in the proof of article 11 such as economic evidence already available in Indonesia, the KPPU will be able to prove legitimately and convincingly the cartel practices carried out in oligopolistic industries such as aviation, pharmaceutical, cement, infraStructure, telecommunications, and similar industries.