Nine out of ten scheduled take-off and landing slots at Sydney Airport were operated in the six months to March 28, according to new data from slot manager ACL Asia Pacific.The Northern Winter 2025 (NW25) end of season report from ACL reveals that total utilisation of slots allocated for Australia’s busiest airport was 95%.
This figure was calculated by combining the 90% of allocated slots flown with the 5% of slots airlines cancelled due to circumstances beyond their control such as war and weather.
Jetstar, Virgin and Qantas, the biggest users of Sydney Airport, operated at close to all their allocated slots, maintaining usage rights for the NW26 schedule, which starts in late October.
It is the first time such detailed slot usage data has been publicly released for any of the world’s major airports, part of the Australian Government’s push to bring transparency to slot management and enforcement practices at Sydney Airport.
The number of operated flights were in some cases heavily impacted by the US-Israel war with Iran through March, when airspace across the United Arab Emirates, Qatar and other Middle Eastern countries closed due to the conflict.
In such cases, impacted airlines – notably Emirates, Etihad Airways, Qatar Airways, Qantas and Virgin – were given slot usage dispensation, allowing them to retain the unused slots for next season.
Airlines that consistently breached the 80:20 ‘use it or lose it’ rule* during the period, without a valid reason, lost the automatic right to that slot in NW26.
Most airlines operated the vast majority of their slots and had retention rates of more than 95%.
At the other end of the spectrum, Tianjin Airlines retained just 33% of its slots, Hong Kong Airlines 71%, and China Eastern Airlines 76%.
On time performance
More than 25% of operated flights missed their slot (a 15 or 30 minute window to either take-off or land depending on sector length) over the period.
Most of these flights were late, potentially disrupting the airport logistics and passenger flow.
International flights were more likely to be on time with 83% of flights landing or taking off within their allocated slot window, while domestic on slot movements were 72%.
The major reason for missing slot windows was airlines arriving late due to consequential delays from previous sectors.
Comment from Darren Batty, Coordination Manager – Asia Pacific, ACL
“Airports need confidence that every available movement is being used effectively. ACL’s approach delivers strong utilisation and operational performance while preserving capacity for future growth – a key priority for airports across Australia,” said Batty.
“At Sydney, we continuously refine how slots are used – aligning schedules, clearing waitlists and responding to operational changes in collaboration with airlines, Sydney Airport and Airservices Australia to deliver strong utilisation and ensure the system remains responsive to demand so that there’s still available capacity for airline expansion.”
Click: Northern Winter 2025 end of season report.
*The ‘80:20 rule’ is the global benchmark for slot management. Slots are allocated every six months for the so-called northern summer and winter seasons and an airline must use their allocated slots at least 80% of the time to ensure they retain them at that airport for the next equivalent season. Either use it or lose it.
