Arch was buried on Sunday, after a private funeral with family and friends. The wreckage of the helicopter is being examined by experts in Vienna.
Arch died instantly from a broken neck after the helicopter he was flying crashed in steep terrain in the Grossglockner mountain area at night.
Experts say that flying conditions were good that evening but that the helicopter may have had a technical failure, causing it to crash into the side of the mountain when Arch steered it to the right.
There is some speculation that he hadn't been authorised to make the night flight and perhaps wasn't properly equipped for flying in the dark, but that hasn't been confirmed.
Arch was accompanied in the helicopter by Reinhard B., a 62-year-old German who runs an Alpine hut which Arch had delivered supplies to. The German was seriously injured in the crash but survived.
The pair set off on Thursday evening, around 2,400 meters above sea level. They planned to land at Salzburg airport but almost a minute after takeoff the helicopter crashed against the rock face and fell between ten and 20 metres down a steep rocky gully.
The crash transmitter in the helicopter immediately sent a distress signal to the flight control authority Austro Control but passenger Reinhard B. waited for eight hours trapped in the wreckage as the rescue team struggled to make its way to him through steep and dangerous terrain.
He told Germany's Bild newspaper that he would never forget the sound Arch made as he died.
He said that as they took off he could only see the beam of the take-off and landing lights and then it was nothing but darkness, with Arch navigating using only his headlights.
Out of nowhere, a wall of rock suddenly appeared. Reinhard B. said that Arch desperately tried to steer the helicopter away from the rock, but it was too late. He survived with fractured vertebra and a broken elbow.
The five-seater, single-engine helicopter was a Robinson R66 model from US manufacturer Robinson Helicopter which has its headquarters in California. It was registered under Arch's name in June 2015.
The last fatal accident involving a Robinson R66 was in Arizona in June. Two men died.