On February 11, Thomas landed his Cessna aircraft at the Yards Gully airstrip in the valley.
A witness, who was part of a nearby fishing party, saw Thomas' plane make two passes before landing on the third pass.
The plane crashed and the witness ran to help. Thomas and the plane's other occupants, two English tourists, were not injured.
When asked what had happened, Thomas said: "I hit a rock ... I should have known better."
When interviewed by a DoC ranger, Thomas admitted he did not have a permit.
The court was told he had been flying with two friends and had landed to take photos.
Ms Williams said Thomas had known a permit was required as, not only had he been told when the park was created, but he was involved in the consultation at its formation.
Ms Williams said DoC was disappointed that it had been left with no other option than to go ahead with a prosecution.
Defence counsel David Jackson said Thomas had been flying for more than 30 years and knew the area well.
"He probably knows every blade of grass," he said.
As a man with huge involvement in the community, Thomas' unblemished record was a matter of personal pride, Mr Jackson said.
He said Thomas was remorseful and embarrassed about what had happened.
Judge Joanna Maze said Thomas had intentionally breached the law by landing without a permit.
"There is no challenge that you knew the concession was required," she said.
However, Judge Maze said Thomas' wrongdoing was at the lower end of the scale.