Travellers have faced hours of disruption at Sydney Airport after air traffic restrictions triggered widespread flight delays and cancellations across the country’s busiest aviation hub. Qantas said more than 50 flights were delayed and four were cancelled, while Virgin Australia reported 20 delayed services and two cancelled Melbourne flights. Airservices Australia said the restrictions were introduced to safely manage demand but have since been lifted. “Airservices this morning enacted Air Traffic Flow Management measures at Sydney Airport due to operational restrictions to safely manage projected airborne and departure demands,” a spokesperson said. “Airservices air traffic controllers are incredibly proud and dedicated to performing what is a demanding, safety-critical role,” the spokesperson said.