International air travel becomes more affordable over the years with the introduction of low-cost carriers (LCCs) in Asia Pacific. As a result, this region has seen an exponential growth in its air traffic movements. Asia Pacific has been recording faster air traffic growths, compared to regions such as Europe and North America. This is largely due to emerging markets and developing economies in Asia Pacific. This is especially seen in the demand and supply for LCCs in Southeast Asia. Changi Airport, being one of the major air traffic hubs in Asia, is facing overloaded traffic in the future due to this exponential growth. Although a new runway and new terminals are proposed and in the process of being built, the coming years could still bring a huge challenge to the airport, if its existing capacity is not maximised to cope with the increasing traffic demand. Hence, we studied the impacts of increasing LCC flights on the airport runway capacity. Different runway operational scenarios were simulated to investigate their advantages and disadvantages. It is found that the segregated parallel arrival-departure runway operation is beneficial. By simulating various operational scenarios with the projected increasing flight movements, it is found that a dedicated runway to medium-sized arrival aircraft may be more beneficial, as this would possibly enable it to have a higher runway capacity.