He began shouting and rocking, punching a wall before breaking the seat in front of him.
The youth noticed the female staff member reaching for handcuffs as the other staff member tried to restrain him.
"Handcuff me b.... and I will punch you in the face," he said.
He then punched the woman, breaking her glasses and splitting her lip, before assaulting the other staff member, leaving him with a bleeding nose. Passenger then intervened.
The youth was met by police in Christchurch and taken to a secure youth justice residence. The staff members were taken to hospital for assessment.
Fairfax said the report referred to the youth's previous history of assaults on staff, the risk of damage to the aircraft and injuries to passengers, as well as possible media coverage.
In a statement, Ministry for Vulnerable Children youth justice residences manager Ben Hannifin apologised for the incident.
The youth was assessed before the flight and had not been agitated or aggressive.
"Unfortunately, the complex and chaotic nature of the lives these young people have lived means they don't always respond to stress like you or I would.
"We take this into account; we have highly skilled staff who are really experienced and know the kids. It in no way excuses the behaviour, but is important to factor in."
Hannifin had written to the passengers who assisted on the flight, apologising and thanking them for their support.
"While our staff are well trained, it's still incredibly traumatic to experience any violence."
No arrests have been made.