The inflated roof of the Subway Soccer Centre to collapsed Monday in Calgary. ((CBC))

The collapse of the inflated vinyl roof at the Subway Soccer Centre for the second time in two years has some parents concerned.

The northeast corner of the dome caved in Monday morning while the facility at 7000 48th Street S.E. was empty.

If there had been children under the dome when it collapsed, they could have been trapped under tons of vinyl and ice, said soccer mom Alison Boyd.

"It could have been catastrophic," she said.

"Take a group of 500 patrons in the soccer centre, possibly one or two staff, no common understanding of what we have to do. I just have no faith they could evacuate us in under five minutes."

The deflation seems to have been caused by one of the roof's anchors snapping and ripping a hole in the dome, said Perry Logan, general manager of the soccer centre.

"We're very diligent for our safety and we take it very, very seriously because of the amount of people that go in there," he said.

The facility holds five soccer fields and the roof collapse has created serious scheduling problems for the estimated 15,000 soccer players who use the building.

A new kind of roof might have to be installed to make sure there isn't another collapse, Logan said.

In December 2008 a piece of ice pressed against the fabric bubble and deflated it, leading to a $1-million repair job.

"There has to be an alternative. I mean again, it's going to be public perception, safety, obviously," he said.

"It's just going to be a big dollar conversation that has to be addressed. We'll start that process sooner than later now," he said.