A suspicious scrub fire at Karikari Peninsula on November 30 had quickly spread down to a nearby beach putting the safety of residents and property at risk, the coroner said.
Mr de Ridder had flown over the fire with a monsoon bucket at 8.22pm but stopped fighting the fire when conditions grew too dangerous.
Panicked residents trapped on the beach began phoning emergency services. A decision was made to take to the air an hour later for what was believed to be a reconnaissance flight to assess the situation.
"Flying conditions had deteriorated to the point where Prickles had made a decision that he would no longer fly with the monsoon bucket as it was too windy and conditions were dangerous. It was at that point that he was contacted to pick up Mr Macrae so they could have a further look at the fire. It was accepted they were initially planning a reconnaissance flight.
"It is also at that point they had received, obviously, information that people were still trapped on the beach. It was getting dark. It was smokey and it was well known that Prickles did not like to fly in smoke as it was simply dangerous.
"However, these two very experienced men, in a 6-8 minute discussion whilst they sat on the ground in the helicopter, must have considered all of those factors and then decided it was safe enough to have a look at the situation."
The pair flew at low altitude underneath the cloud and close to sea level.
At 9.38pm the helicopter was reported missing and a loud crash was heard by those trapped on the beach.
The helicopter and its two crew were found in seven metres of water the next day by police divers 680m from the shoreline.
The coroner said it was more than likely that as they started towards the beach the flying conditions were acceptable.
However, the conditions changed dramatically with the rolling back of the smoke which made for treacherous flying conditions, distorting the pilot's spatial orientation and resulting in the crash.
Mr Shortland said both men were very experienced and respected fire fighters. They had a history of making good decisions under pressure.
"They made a decision to try and assist given the report people were trapped on the beach."
Mr Shortland said there was confusion in terms of communications, chaos, possible misinterpretation of the available information until command and control was established.
"I accept there was emotional pressure brought to bear on the New Zealand Fire Service operator from those on the beach using the 111 emergency calls. These calls were stressful resulting in a building up of emotional pressure and anxiety."
The deaths highlighted the need to have an extra level of safety in the overall planning strategy when using helicopters to fight fires, Mr Shortland said.
