West Australians are still no closer to finding out when they'll be able to catch a train to Perth Airport, more than two years after the long-awaited rail line was due to open.

The Forrestfield-Airport Link has been more than a decade in the making and is now nearing completion.

But exactly how long the final stretch will last remains unclear, with the government refusing to give any certainty beyond an opening some time this year.

The opposition said that was because the government had something to hide and called on Transport Minister Rita Saffioti to provide a date soon.

Uncertainty around the line's opening comes amid chaos at the airport, with flight cancellations and car parks filled to the brim.