The management of oil exploration is among the most important strategic tasks that a nation has. In Brazil, the Campos Basin is a petroleum rich area compassing oceanic fields that accounts for 80% of Brazil's oil production. Because the Campos Basin is offshore, there is a high volume of helicopter traffic in the area. Currently, the Department of Airspace Control, that manages the Brazilian Air Traffic System, is developing a plan to improve Air Traffic Control Operations in this area using ADS-B technology (Automatic Dependent Surveillance-Broadcast). ADS-B will be used in a restricted oceanic airspace to supplement radar coverage to provide better service. As ADS-B technology is new and has vulnerabilities (unencrypted messages in a broadcast transmission mode), understanding the impact of a cyber-attack on the safety and security of Air Traffic Control Operations is a major challenge. This paper provides a case study in the evaluation and assessment of cyber-attacks to critical infrastructure using Simulation Tools. An analysis of the Simulation Environment used and its suitability for its purpose will be presented as a key finding. This environment consists of: 1) a cyber-attack generator; 2) an entity-level simulation to provide the dynamic behaviors of entities (helicopters and ATS infrastructure); 3) a network simulation that will include modeling ADS-B; and 4) a 3D visualization tool. The HLA protocol will be used to integrate selected components of the testbed. To provide information about the impact to the Campos Basin Air Traffic System, an external tool will be used to export the information to a Log System, for analysis by a cyber-assessment tool. This testbed will be used for developing an impact assessment framework that is applicable to a wide range of military and civilian missions.