Infrastructure analysts at the Commonwealth Bank warn that Sydney Airport may hit capacity 20 years earlier than it expects.
The airport's management has previously said it will have sufficient capacity to meet the city's air transport needs until 2045.
However, Commonwealth Bank infrastructure analysts Andre Fromyhr and Matt Crowe estimate that Sydney Airport is likely to near or reach its maximum capacity in 2025, based on the bank's passenger forecasts.
The bank's estimate is consistent with a finding by a joint Federal and NSW Government study that found signs of constrained capacity would emerge at Sydney Airport from around 2020.
That report found that all peak morning (6:00am-12:00pm) and evening (4:00pm-7:00pm) weekday slots would be allocated by 2020, and that there would effectively be no free slots by 2027, with unmet demand for more than 100 flights per day.
While Sydney Airport is likely to hit constraints in about a decade, the CBA report finds that it could currently handle 61 per cent more passengers if it matched world's best practice utilisation of existing facilities, exemplified by Beijing's main airport.
London (Heathrow), Hong Kong, Bangkok, Atlanta and Tokyo's Haneda airport rank next for capacity utilisation, with Sydney in the middle of a group of 20 airports studied by the bank, with a similar utilisation to Charles De Gaulle Airport in Paris.
However, Sydney had the best utilisation rate of any airport in Australia, comfortably above Melbourne and well ahead of Brisbane and Perth.
To match Beijing, the analysts suggest Sydney Airport could increase the number of flights by 34 per cent and cater more for larger aircraft to increase the average number of passengers per flight by 19 per cent.
The report also noted that less restrictions on the number of flights and a reduced night time curfew would increase the Sydney Airport's capacity, but that these seemed unlikely to occur in the short-term, given intense political opposition.
However, the report also finds that Sydney Airport will almost certainly need to spend more on staff and facilities to cope with the increase in passengers, even if it does not expand its capacity.
CommSec analyst Juliana Roadley told ABC News 24 that changes in technology mean Sydney Airport must keep investing in infrastructure to keep up with increasing demand.
"If you're seeing more passengers arriving you've got to come up with more avenues of access for those arrivals as well, and that'll mean more taxi bays, more parking, so its really a growth structure over time," she said.