This study tried to get the accurate air demand forecasts for improving the capacity of aviation safety facility and presenting how we manage the air traffic growing, using Seasonal ARIMA(Autoregressive integrated Moving Average). For this purpose, we used monthly data, which was a combined total of domestic and international flights from January of 2012 to July of 2017 of the Gimhae Airport. As the result, in 2018 the passenger may increase to 19,304,778, in 2019 to 22,451,185, so we have predicted the demand of domestic and international flights will continue to increase. On a monthly basis, the demand of flights may be high in order of December, November, October, August and September of 2018, on the other hand, in March and February the demand of flights may be the lowest. In 2019, the demand of flights may be higher in order of October, December, November, August and July, but in March and February, it may be the lowest. Considering these forecasts, it is necessary to consider a strategic alliance that will expand the number of flights operated by domestic and overseas large airlines and low-cost carriers with code-share as Gimhae Airport demand for air travel increases. Also, it is necessary to promote the expansion of the Gimhae new port to overcome the current capacity, and it should be supported by the policy leadership.