Thousands of passengers faced significant disruption on Tuesday as staffing shortages within air traffic control led to widespread flight cancellations and delays at Sydney and Melbourne airports.

Airservices Australia warned travelers of potential delays of up to an hour, with ground delays expected to continue throughout the day in Melbourne. Restrictions at Sydney Airport were slated to lift by 2 p.m., though strong winds also contributed to flight disruptions in Sydney.

At least eight flights were canceled, affecting an estimated 1,200 passengers. Airservices Australia advised passengers to verify their flight status before traveling to the airport.

The disruptions come as safety concerns at Sydney Airport have been mounting. In the past two weeks, two near-miss incidents involving aircraft have occurred. Most recently, a Jetstar flight bound for the Gold Coast narrowly avoided colliding with a Qatar Airways plane on Sunday. Two employees were stood down for mandatory testing following the Sunday incident.

Rob Sharp, chief executive of Airservices Australia, has been summoned to Canberra for emergency talks with the federal government. He issued an apology for the recent wave of delays at Sydney Airport, stating that while safety is not compromised, measures are put in place to reduce traffic levels, which can result in delays.