One of the management problems in the most frequent airports is the application of delays at the time of departure or arrival of a flight or even the arrival of an unplanned flight. These changes require real-time decisions that can lead to delays in other flights if not managed correctly. That is why airports require automatic simulation systems to avoid management and planning problems. This project offers a standard solution for managing the reallocation of parking sites by looking for the available slots in the tactical phase, taking into account the characteristics of the airport, the data of the stands and the air traffic of the studied airport. Specifically, these data is extracted from Orly Airport (France). The main purpose of the stand assignment simulator in the tactical phase is to offer an assignment proposal with planning changes at a specific airport. Another objective of the simulator is to be independent of the airport and be able to be executed at any aerodrome with different characteristics and enviroment. The present simulator has been developed in Java applying external requirements. The most relevant requirement is the modularity of the simulator. The system has been designed to be embedded and scaled in the future with other modules and features of an airport simulator. The data of the Orly Airport have been obtained from the Aeronautical Information Publication (AIP) with the help of Google Earth tool and Eurocontrol. This information is analysed and treated by the simulator and applying criteria and restrictions presents the re-allocation of parking places. The algorithm used is based on the classification of parking sites for priorities and preferences, taking into account whether it is remote, the distance to the runway or if it has finger to access to the terminal. The restrictions on the allocation of stands are given by the size of the aircraft with regard to the size of the stands, the type of flight (for security factors), commercial agreements between airlines and airport managers and minimize taxi time of the aircrafts. The simulation obtained by the system presents a new allocation of stands including the changes to the original daily planning, either by changes of arrival time or the incorporation of new flights. The most relevant result obtained from the Orly case is the distribution of the delay between the aircraft, which destabilizes the planning of flights. A second result is related to the offer/demand balance of the Orly Airport; It is concluded that taking into account only the number of stands, Orly Airport could plan more flights.