Both Air New Zealand and Prime Minister John Key are defending the diverting of a flight to pick up the stranded prime minister from New Plymouth and deliver him home to Auckland.
The Mana Party's Waitakere candidate, Sue Bradford, says the incident shows Mr Key has "gone power crazy" and goes beyond National's "normal born-to-rule arrogance".
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Ms Bradford said a passenger on the Thursday evening flight, which had meant to fly directly from Nelson to Auckland, contacted her, angry that it was redirected to New Plymouth for "operational" reasons.
"Little did they realise that 'operational' meant their flight was diverted simply to pick up the Prime Minister. The whole flight was over half an hour late as a result," Ms Bradford said.
The Prime Minister's office said that Mr Key did not ask for the flight to be diverted after his own New Plymouth-Auckland flight was cancelled because of an aircraft breakdown.
It was standard practice for Air NZ to divert flights to pick up stranded passengers, the office said.
Air New Zealand, in a statement, said the cancelled flight was the last of the evening and there was no opportunity to transfer affected passengers to Auckland.
The diverted aircraft had spare seats for seven passengers including Mr Key and his entourage.
"Air NZ does occasionally divert flights to pick up passengers from cancelled flights if there is limited or no opportunity to re-accommodate those passengers onto other services directly from that airport."
Passengers were informed about the diversion before the flight, Air NZ said.
Mr Key has been criticised for his use of RNZAF helicopters and Beechcraft Kingair for travelling to his engagements.