An external network outage is impacting the check-in system.
Travellers are being urged to contact their airline about delays - domestic flights are largely unaffected.
One passenger told our newsroom she's been waiting there since 3.30am, and their flight's delayed until at least 3.15pm.
Herald Travel reporter Sarah Pollok is there, and says she hasn't seen an airport this busy is a long time.
She says they've added additional barriers to manage the queue, which is nearing the entrance of the airport - and there's not a lot of room to move.
