From the news report:
The Civil Aviation Safety Authority (CASA) confirmed that one of the planes was a Piper-Seminole aircraft operated by flying school Moorabbin Aviation Services that had departed from Moorabbin.
The other was a Beechcraft Travel Air, operated privately out of Tyabb, on the Mornington Peninsula.
CASA spokesman Peter Gibson said they were operating on instruments, meaning the pilots were flying visually and would have lodged flight plans before takeoff.
“We don’t have any explanation of what happened. We can’t speculate on that,” Mr Gibson said.
Logansi - it's not a direct quote so it could be the reporter did not know what CASA were talking about and intepreted the CASA statement to suit the reporter.