A security officer who planted a fake bomb at Dunedin Airport says the evidence used to convict him was insufficient.
Preetam Prakash Maid, 33, was jailed for three years before the Dunedin District Court in January after a jury found him guilty of a charge under the Aviation Crimes Act.
The incident occurred just two days after the Christchurch mosque attacks, which Judge Michael Crosbie said made the hoax particularly cruel.
Maid has maintained his innocence throughout and yesterday the case was called before the Court of Appeal, which is sitting in Dunedin this week.
Counsel Len Andersen QC accepted there was enough circumstantial evidence to suggest his client planted the device but said that was ''clouding the issue''.
The specific charge was: taking an imitation explosive device into a security enhanced area.
The Crown said that occurred when Maid took the fake bomb - inside a laptop bag, which was inside a black backpack - out to his patrol vehicle before his perimeter check.
Andersen, who was appealing the conviction and the sentence, said there was no real evidence to support that assertion.
''When does a theory become circumstantial evidence?'' he said.
Maid had been vocal with superiors about what he perceived to be inadequate security in some areas of the airport and the Crown, at trial, said the bomb hoax was his way of exposing those supposed shortcomings.
Swipe-card analysis showed that on March 17, 2018, the defendant twice entered a corridor to the dangerous goods store, spending 20 minutes there.
Maid took items from the storeroom - a SodaStream gas canister, a decommissioned cellphone, and red and black wiring - and stashed them in a laptop bag knowing it would resemble a bomb.
While conducting a perimeter check of the airport, he slipped the bag into the alcove of a ''localiser hut'' at the north end of the runway and reported finding it there to his superiors.
Once the item was neutralised by the New Zealand Defence Force, police picked through the remains and discovered the items inside had come from within the airport.
Possibly the most critical piece of evidence for the jury came from a cryptic handwritten note wrapped around the bag's handle.
''A: Alpha, B: Birds, C: Crash, D: Dunedin, E: Emergency, F: Fools,'' it said.
The court was shown a comparison of Maid's handwriting and the penmanship from the note, and a forensic document examiner said she was confident the defendant was the author.
Andersen accepted it was the strongest evidence of his client's involvement.
''This was a very silly, disruptive and dangerous course of conduct,'' Justice Denis Clifford said.
A Probation report on Maid described him as ''intelligent and articulate'' but said his explanation of events appeared ''rehearsed''.
As part of his sentence, he was also ordered to pay $6000 reparation, though the court heard the total cost of the disruption was incalculable.
Justices Clifford, Matthew Muir and Susan Thomas reserved their decision.