Wade Liknes holds up a bag full of ice that allegedly fell off a plane, crashed through the roof of his house narrowly missing his wife who was sitting on her bed talking on the phone. The ice passed through the shingles, plywood and drywall and left a hole about a 12 inches in diameter. (SUN MEDIA/Jim Wells)

Ice from a plane, possibly from a toilet, plummeted to earth and punched through the roof of a southeast Calgary house yesterday, narrowly missing a woman who was in the home.

Marian Liknes said she had just entered her bedroom to answer the phone shortly before 9:30 a.m., when a massive chunk of ice crashed through the ceiling with a deafening blast, mere centimetres from where she was sitting.

"I thought it was a gunshot at first and I ducked, I ducked down and I was scared, I was really scared," said Marian.

"Then I got a bit hysterical, crying and shaking.

"Two feet over and it could've killed me ... the police said it would've killed me."

The frozen missile punched through roof shingles, wood, insulation and drywall with explosive force, leaving a half-metre hole in the house, located on Riverbend Dr. S.E. -- and the bedroom littered with debris and ice, said the grandmother of four.

Marian was struck by flying shards of ice, which at the time she thought was glass.

She ran for cover, ducking into the couple's ensuite bathroom.

"I peeked out and there was this huge hole in the ceiling ... and there was ice everywhere and this huge chunk of ice on my bed, about two feet from me.

"Two hours earlier, my husband would've been lying on the bed."

The couple lives under the approach path for Runway 34 of the Calgary International Airport and are accustomed to seeing jets above them, said Marian's husband Wade.

"Some days you can see them stacked up one right behind the other," he said.

"So, it's not unusual to see planes coming in, but it is unusual to have stuff fall off of them."

The Transportation Safety Board of Canada is gathering information on the incident, but is not clear what kind of plane or which airline was involved.

Although the safety board has not officially determined the cause of the incident, investigators believe it was likely frozen waste water from an airplane's toilet system, said board spokesman Johnathan Lee.

In the past, O-ring valves -- used to drain planes' toilet water -- have leaked while in flight, prompting the water to freeze to the outside of the fuselage and dislodging in the form of an ice chunk when the aircraft drops in elevation, he said.

"These kinds of occurrences are rare, but not unheard of," said Lee, adding this is the first such incident in the Calgary area in at least nine years.