The son of an Aviation Security officer whose dog was shot dead at Auckland Airport says it has been "traumatising" for the family.
Sixteen domestic and international flights were delayed for three hours as ground staff tried to catch explosive detector dog Grizz on Friday morning.
Police say Auckland Airport staff eventually directed airport-based police to shoot Grizz, saying they were left with no other choice.
"This is not an outcome which anyone wanted, and police were only asked to be involved as a last resort," Counties Manukau District Inspector Tracy Phillips says.
Nicky Thorburn posted to Facebook that his father Noel, who had worked in customs and aviation for more than three decades, was "very upset" about what happened.
The shooting also sparked major debate online over whether Grizz needed to be killed.
"I'm reading disgusting comments... and people need to understand how traumatising and upsetting this was for him," Mr Thorburn wrote.
"Please have compassion."
Grizz's shooting has left animal rights group SAFE "appalled" at the decision.
Spokesman Hans Kriek disputes whether Grizz needed to be shot, saying they had plenty of time for a non-lethal alternative.
"Appalled was my first reaction and I'm still appalled with my later reaction because there was no reason for them to shoot that dog," he told Newshub.
"They could have used a tranquiliser gun of course, and that would have resolved the issue straight away with good results for the airport and good results for the dog."
However, an aviation commentator says it was the right move to keep the airport running.
The death of Grizz
The 10-month old bearded collie/German short-haired pointed cross was six months from graduating and was still getting used to the airport environment.
He was "spooked" by something while being loaded into the back of an Avsec vehicle in an airport public area around 4:30am.
He escaped through the security protected area and managed to get to the security area when a gate opened to let a truck through.
Avsec says a full-scale search was launched, including all off-duty Avsec dog handlers, but it was made more difficult because it was dark.
When they did eventually find him, he wouldn't let anyone approach and kept sprinting across the runway.
Avsec says they "tried everything" including food, toys and other dogs but to no avail and because the area was too big, using mobile fencing wasn't possible.
Grizz didn't have a dedicated handler so wasn't as responsive as the more experienced dogs with a single handler.
Mr Kriek says although the airport didn't have a tranquiliser gun on hand at the airport, there was enough time to borrow one from other organisations such as Auckland Zoo.
"We just can't understand what the hell was going on there."
Grizz was not on the tarmac at the time of shooting.
Animal behaviourist Mark Vette, who is working with the Avsec team, has defended not using a tranquiliser gun, saying it would only be effective under certain conditions which didn't exist on Friday.
"Normally that's very tricky - and I ran a zoo and am trained with dart guns – it's very difficult to hit an animal more than 30 metres away, let alone at night when it's black."
Avesec spokesman Mike Richards says the handler and wider team are "naturally upset".
"But [they] do understand there were no other options in the very difficult circumstances."Flights were delayed as pilots would not risk passenger safety with a dog on the run.
They resumed at 8am, though there was a backlog of flights.
Aviation industry commentator Peter Clark says the decision to close the airport for three hours was "generous" given the amount of lost income and passenger inconvenience.
He says it was the "right decision" to shoot Grizz.
"I think it was a necessary decision. You cannot close Auckland Airport for any length of time. It costs hundreds of thousands of dollars for airlines, passenger inconvenience, and somebody had to make that decision," he told Newshub.
"It probably should have opened a lot earlier."
Grizz had become a safety hazard which could have been calamitous and needed to be resolved quickly, he says.
"Small aircraft hitting an object like that could be quite catastrophic on takeoff or landing so the decision was right, and they had to take that safety issue away in order to operate."
A review of the incident will try and figure out why the dog was spooked, and whether it means their dog training needs to change.
Mr Kriek believes Grizz's death needs to come with lessons any possible repeat situations including keeping a tranquiliser gun at the airport.
"These things could happen again...hopefully they will now introduce some better systems of how to deal with these situations in the future.
"They need to be prepared for something like this and they clearly I think were unprepared for it and didn't have the right equipment to deal with it."
However, he admitted such criticism was easy make in hindsight.
"They might never have envisaged something like this happening and that's why we're saying learn from it, let's make sure this never happens again."
The work of Avsec dogs
Avsec dogs are different to Customs or Ministry for Primary Industries dogs; their primary role is to sniff out explosives to make sure no dangerous material gets inside planes or the airport.
The dogs are highly trained and costs up to $100,000 to train through to final graduation.
Their search areas include carparks, unattended items and cargo and aircraft, as well as random searches.
They also help police and other agencies during bomb threats at airports and elsewhere.
The dogs are based at airports in Auckland, Wellington, Christchurch and Queenstown.