The study of the capacity of an airport has been -and will keep being- one of the most common and necessary activities to do when designing an airport. An efficient airport means a good performance, and therefore good incomes. To design the air-side of an airport, we must find the proper configurations according to the estimation of traffic that we aim to obtain. We also need to look further at the future, and not only prediccting how will it change in the following years of its opening. What will happen in 10 years? Will it need an extension? Will we have enough space to satisfy the demand? This is intended to stress the importance of forecasts and analysis that are done for the capacity of an airport.