The trio opted to play it safe with less difficult jumps to ensure their progression to the 12-woman final on Wednesday night.
Lassila, considered one of Australia’s top gold medal hopes at the Vancouver Winter Olympics, qualified in ninth position with a score of 167.55, while Gardner was 10th (164.60) and Cooper 11th (162.99).
But Lassila, who has two aerials World Cup victories this season, blasted the judging as inconsistent.
"I saw Xinxin from China do a full-full-full and she crashed it and got 88 points, so, that doesn’t make sense. I stomped a double-full-full and got 85," she said.
"Even though her degree of difficulty is higher, she still crashed and that’s something I don’t really understand."
Cooper was also confused by some scoring decisions.
"It would have been a big problem had I not made it, but Lydia is in, I’m in, Liz is in, we have three Aussies in. As long as we’re in and we’ll leave the judges to sort it," Cooper said.
Cooper, a veteran of five Olympic Games, was pleased to come through qualifying unscathed.
"The aim of the day was to be flexible and start off with a double twisting double, see where that positioned us and me running later was fantastic because we were just watching the others go and seeing what scores they got and what we needed," Cooper said.
"I just wanted to get in and get to Wednesday’s final and do my big jumps which I’m looking forward to unveiling."
Gardner, who was fourth after her first jump, dropped back to 10th after missing her second landing.
"I had two solid jumps, they weren’t fantastic but landed," Gardner said.
Australia’s other competitor Bree Munro missed the landing on both her triple somersaults for a total score of 143.46, placing her 18th to miss the final.
"I was happier with my classical leg, which is unusual for me, as I usually prefer the free."
"My equipment was good. We got the waxing right on my skis, but the warm conditions are always tough. It was a bit like skiing back home in Australia."
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