Current rules force airlines to use the time slots at busy airports at least 80 percent of the time or face losing them the following season. After the European Parliament agreed to loosen these “use-or-lose rules”, airlines will gain more flexibility in how they use take-off and landing slots: They will be entitled to the same series of slots during the summer 2010 season as were allocated in 2009, regardless of how much they use them.Source: AEA information