Low light and "what I would describe as whiteout conditions'' hindered a clear view of it.
"I'd never seen one take off at that angle before, quite honestly.
"Normally, they come out and climb, but this one sort of didn't.''
The aircraft did not follow the steep angle "that I would expect ... it just didn't look quite right''.
He watched it fly past him and continue east up the Frankton Arm before it banked left at an angle of "about 20 to 30 degrees'' near the Queenstown golf course.
It then flew back towards Jardine Park before Mr Clark lost sight of it.
Under cross examination, he confirmed to defence counsel Matthew Muir by "whiteout'' he meant a "very low cloud layer''.
St John office administrator Lynn Cain said she was outside her Douglas St property having a cigarette between 5.20pm and 5.25pm when she heard the "roar'' of the plane starting up.
She saw the plane "power off'' and sit under the cloud, something she had "never seen'' before.
Initially thinking "they were pushing to get out of town at that time of night'', she continued to watch, as she was "rather concerned''.
The weather had "closed in'', with a "misty cloud layer that appeared to get thicker as it went up'', while the "tail of the plane just seemed to be attached to the cloud''.
She stood on a stool outside to try to see the plane and remained outside after she had lost sight of it, listening, "until I knew it was well out of range from us ... east of the runway ... over the Shotover Delta''.
Queenstown boat skipper Max Perkins - also a pilot - told Judge Phillips he had emailed the CAA after reading reports of the incident online which he felt were "sensationalised''.
"It was when people were implying the plane was extremely low, below 1000ft and doing steep turns.''
He was parked on State Highway 6 near the runway and saw the plane take off, climb and then "level off underneath the cloud base''.
It flew east and then banked about 25 degrees, turning to proceed west towards Deer Park Heights, where he lost sight of it.
"I read an article online and ... I was spurred on by that just to tell the CAA what I saw, for what it was worth.
"I felt that it was being sensationalised in the media.''
The hearing continues today.