Nathan Theobold said his father's death continued to have a "devastating" impact.
"The day he died, I lost one of my true mates."
Before the crash he had plans to move south with his family and work with his father, he said.
"Every day when I wake up, I think about what could've been.
"This whole thing has ruined my life, my future."
Theobold's daughter, whose name was suppressed, said her children would never know their grandfather and have the "connection they deserve".
A Transport Accident Investigation Commission (TAIC) interim report two months after the crash said there were "strong'' indications a pair of over-trousers had come out of the helicopter through an open door and became "entangled" with the tail rotor.
Less than a minute after the helicopter took off at 10.53am, several witnesses recalled seeing the helicopter descending near vertically, the report said.
Items were seen coming out of the helicopter towards its tail rotor before it began to rotate and descend.
The tail section separated from the helicopter before it struck the ground and caught fire.
The TAIC investigation is continuing and a final report is yet to be released.
The crash occurred less than three months after Nick Wallis' brother and fellow pilot, Matthew, was killed in a helicopter crash in Lake Wanaka.
The company, founded in 1954, is majority-owned by aviation entrepreneur Sir Tim Wallis and members of the Wallis family.
Sir Tim did not attend today's sentencing due to ill health.
The case was set down for a judge-alone trial in August, but the parties agreed on a summary of facts a week beforehand, and the company admitted amended charges.
Civil Aviation Authority lawyer Stephanie Bishop said the company failed to internally report and investigate three previous in-flight door opening incidents with the helicopter — on October 3, 12 and 16.
It failed to ensure a culture of reporting such incidents, and did not follow its own processes for restraining loose items inside the aircraft, Bishop said.
The company allowed a "culture of non-reporting to become normalised".
The Alpine Group counsel Garth Gallaway said it accepted those failures, but they were not "causative" of the crash.
It was not known at which point in the crash sequence the overalls hit the tail rotor, and that contact could not be established as the accident's "initiating cause", Gallaway said.
The company had voluntarily made payments of $200,000 to each of the three victims' families, and offered further payments of $50,000.
Judge Russell Walker said the reporting and restraint failures were closely linked, and "significantly increased" the nature and seriousness of the risk.
It was clear there was a "casual attitude" in the helicopter industry towards reporting door-opening incidents.
However, he agreed with Bishop acceptable standards should not be "judged by what others were doing, but by what they should have been doing".
There was an "obvious risk" of death or serious injury as a result of the company's failure to follow its processes for restraining items, Judge Walker said.
After discounts for the company's guilty plea, remorse, payments of reparation and the steps it had taken to improve its health and safety processes since the accident, he came to a fine of $315,000, as well as prosecution costs of $64,000.
In a media statement, The Alpine Group said it accepted some of its systems and procedures before the accident "could have been improved".
"We are a family business with a proud safety record, and we are devastated by the loss of three wonderful men."
Although the accident's cause would "likely never be known", the company had collaborated with the wider helicopter industry to improve aviation safety and ensure similar incidents could be avoided in the future.
