As air traffic volume is growing around 5% each year in Europe it has become a priority to improve air traffic control in order to deal with tomorrow's air traffic configuration. In 2007 the SESAR (Single European Sky ATM Research) project was created under European Community law as an initiative to design the future of air traffic management over Europe. One of the objective of SESAR is to increase air traffic density and optimize flight route plans. This can be achieved through en-route deconfliction. Reducing the global number of conflicts through speed regulation has been tested in the ERASMUS project (En-Route Air traffic Soft Management Ultimate System) and efficiency of the concept has been analysed through tests and simulations. It provided many insights related to en-route control using speed variations hence becoming a solid reference. In this paper we develop a mixed integer linear model for a speed regulation problem that suits SESAR requirements. We focus on flights crossing times at intersection points rather than distance to ensure separation along our resolution. Speed regulation is thus converted into travel time control. Finally we propose an integer linear program aiming at minimizing the global potential conflict quantity by speed modulations.