Some flights from Christchurch international airport were delayed on Friday after a communications cable was cut.
Jetstar and Air New Zealand check-in terminals were disrupted all morning.
Jetstar was the worst affected, with both domestic and international check-ins being processed manually.
The airport company says the cable was due to be cut as part of ongoing ground work. It was severed only after being cleared by airport staff and an external specialist who both ensured it was not live.
Chief executive Jim Boult has apologised to passengers. He says an investigation will follow to make sure it does not happen again.