A Sydney teenager who typed "I have a bomb" into an in-flight messaging app as the plane he was travelling in prepared to take off has been deported from New Zealand and ordered to pay a $3000 reparation sum.

Meke Fifita, 19, sparked an emergency response after he made the "threatening comment" on Wednesday night while the Sydney-bound Air New Zealand A320 was taxiing to the runway at Auckland International Airport.

The message was posted as the Air New Zealand flight was preparing for takeoff.

He was arrested after the plane returned to the gate, and was later charged with breaching the Civil Aviation Act for providing false information relating to the safety of an aircraft.

On Thursday, Manukau District Court heard Fifita was travelling home to Sydney from Tonga, transiting at Auckland, when he made the false threat.