Southern region coroner and skier David Crerar, of Dunedin, backed evidence given by police search adviser Geoff Wayatt, of Wanaka, when he said 2009 had been "a particularly bad year for New Zealand mountains".
There were three avalanche fatalities and several near-misses by heli-skiers between July 24 and August 15.
At the Queenstown District Court, Mr Crerar heard evidence relating to the death of Mr Campbell, who died on Sunday, August 2, when an estimated 400 tonnes of snow engulfed him in the Dirty Four Creek.
The creek is about 1km across an open ridge to the southwest of the Coronet Peak skifield boundary.
Fraser Charles Campbell, Ryan's younger brother, said the experienced snowboarders had not heard about any avalanche risk that day, or noticed any warning signs at the top or bottom of the Greengates chairlift.
They were not wearing transceivers and did not carry probes or shovels.
He said they boarded underneath the boundary rope and eventually decided to drop into the gully, with the elder Campbell deciding to board around and below a rock, instead of above.
Fraser saw his brother slide downward and what appeared to be an avalanche triggering, about 1m above where he had boarded.
Ryan was upright while Fraser could see him, until he boarded around the rock out of sight.
Two additional avalanches started as Fraser boarded to the point where he last saw Ryan.
"I was calling out to him, but got no response ... there was no sign of Ryan anywhere.
"Away in the distance on the ski area some 100m or 200m away, I saw two skiers hiking up the mountain. I yelled out to them, I screamed my lungs out, actually."The skiers called for help on a cellphone and used ski poles with the baskets ripped to probe the debris.
The first rescuers arrived about 15 minutes later, by which time Ryan had been under the avalanche for 30 minutes, Fraser said.
Mr Wayatt said Ryan triggered a "wind-slab avalanche", which swept the snowboarder down the face for 170m to 200m and into the confined gully under 2.5m of snow.
Mr Campbell's body was recovered at 7.13pm, about two and a-half hours after being buried by the avalanche.
Search and rescuers removed about one tonne of dense snow to retrieve the body and created a heli-pad nearby for the rescue helicopter to land.
Inquest officer Senior Constable Chris Blackford, of Queenstown, confirmed with Fraser Campbell that the two experienced snowboarders were "under no illusions" about the fact they had gone outside the skifield boundary, but he noted they had seen tracks where skiers and boarders had entered the area earlier that day.
Mr Crerar said to Fraser Campbell: "You were the unlucky ones."
Fraser said he did not recall seeing avalanche-risk warning signs at the top of the skifield chairlift.
He said he was aware "more so now" of the need for safety precautions, such as a beacons, and his contemporaries were "definitely" more aware, in response to Mr Crerar's questions.
Fraser said he would report back from the inquest to his parents, Wendy and Joe Campbell, of Auckland, who were not present in court yesterday.
He told the coroner: "Coronet Peak staff did a really good job; they did their best. [It's] just a shame we lost my brother over it."
Sergeant Brian Cameron, of Queenstown, said the coronial autopsy report, on August 3, found tetrahydrocannabinol (THC) in Ryan Campbell's blood, "consistent with the deceased having smoked a single cannabis cigarette within about three hours prior to death".
Sgt Cameron said a small tin containing cannabis leaf material and a cannabis pipe was in Ryan's possession.
Mr Crerar said: "This is a warning that using drugs, such as cannabis and alcohol, requires a safer setting than our mountains."
The coroner said he accepted the incident did not happen on the Coronet Peak skifield and its management was not responsible.
He quoted Prof Han-Seung Yoon, who carried out the autopsy, and said Ryan had suffered a "fatal crash injury" and not suffocation.
Mr Crerar said he would adopt Mr Wayatt's recommendations concerning greater avalanche awareness in his report.
He would advise the appropriate Government minister funding for the New Zealand Mountain Safety Council was essential.
Inquest information
• Ryan Campbell was found under 2.5m of snow when a laptop-sized Recco device detected a weak signal from his digital camera.
• Communication between rescuers was an issue during the search, with limited mobile phone reception.
• The rescue dog did not find Mr Campbell because of the depth he was buried and the number of swirling scents from rescue personnel.
• Avalanche survival statistics from Switzerland indicate a 7% survival rate for burials of 120 minutes.
• Snowboarders are at a higher risk of burial because their boots are securely strapped to their board.
• New Zealand has the third highest per capita avalanche fatality rate in the world - police search adviser Geoff Wayatt.
• A beacon, probe, shovel and partner are back country essentials - Mr Wayatt
