When Changi Airport's Terminal 5 opens in about a decade, it may not be able to handle up to 50 million passengers a year, as is the plan. Depending on air traffic numbers and projections, there could be a Phase 1A and 1B, said Senior Minister of State for Transport Josephine Teo.
Ultimately, the aim is for T5 to handle up to 70 million passengers a year - more than T1, T2 and T3 combined. Flexibility is key in the design of the mega passenger terminal to ensure efficient use of resources, she said.
During seasonal or other lull periods, for example, parts of the terminal could be shut down if necessary to minimise waste, she added.
Keeping an eye on future demand is important, said research firm Endau Analytics' aviation analyst Shukor Yusof.
"The main challenge for any airport today is to manage capacity and cope with future traffic growth. How to achieve this?
"It needs to be cost-efficient and there must be a timeframe corresponding to expanding airport infrastructure according to user demand," he said.
Even as planners are mindful of the industry's volatility, there is confidence that there will be strong growth, Mrs Teo said.
Last year, Changi Airport handled a record 54.1 million passengers, but the growth of 0.7 per cent year on year was the lowest since 2009, when business was hit by the global financial crisis. Industry analysts do not expect the numbers to pick up significantly this year.
The moderation, due in part to consolidation in the low-cost carrier sector, does not change the trends of a growing middle class in Asia and the high propensity of Singapore residents to travel, Mrs Teo said. The slowdown is more likely "a temporary blip", she said.
This is why it is important for Singapore to plan ahead, even beyond T5, she stressed.
"Is there room for further growth and room to organise things even more efficiently?... We are not only looking at 10, 20 years," she said.
"We have to look at SG100 and ask ourselves what might Changi Airport be then... We have to leave enough on the table for the future generations of Singaporeans to work on."
She added: "We have built up a good habit of looking very far into the long term, which I think is an advantage you need given Singapore's land constraints."