TORONTO - A son devastated by the death of his 69-year-old mother last Friday said he's concerned that it took over four hours for an air ambulance to transport her to an Ottawa hospital.

It's still unclear whether his mother would have survived had the air ambulance arrived sooner, said Scott Dearman.

"I just don't want another family to have to go through this if a prompt Air Evac would have saved a family member," an audibly upset Dearman said in an interview. "It's too late for my mom."

Last Wednesday, the hospital in Barry's Bay asked Ornge to transport his mother to Ottawa -- about 150 kilometres east -- for treatment, but were told that no air ambulance was available, he said.

The hospital arranged for a land ambulance, so Dearman's father Clyde went home to pick up an overnight bag before making his way to Ottawa. When he got there, he was told his wife Judy hadn't arrived, so he drove back to Barry's Bay, Dearman said.

An Ornge air ambulance finally arrived -- more than four hours after it was first called -- and took his mother to another Ottawa hospital, he said. His upset father drove back in the rain to Ottawa to be with her.

"My understanding is that at the point that Mom made it to the hospital, it was too late for her," he said.

Dearman, who lives in Victoria, said he rushed to Ottawa with his wife and three-year-old daughter on the earliest flight. But they arrived at the hospital just a half-hour before his mother died. His grieving father filled him in on what had happened, he said.

"When we finally saw her, she was on a ventilator and dialysis," an upset Dearman said. "They were basically keeping her alive until we arrived from Victoria."

His mother, a colon cancer survivor, had an operation in April that allowed waste from her bowels to be collected in an external pouch, Dearman said. Doctors believe that something went wrong and the waste leaked inside her body, creating an infection that irreparably damaged her internal organs.

It's the second time in less than a week that Ornge has failed to respond on time to an emergency call, charged Progressive Conservative Frank Klees.

On the same day that Judy Dearman was waiting for an air ambulance, Ornge also failed to respond to a fatal collision north of Toronto.

The emergency call came in early last Wednesday, but Ornge said it couldn't send a helicopter because the incoming crew -- who had worked overtime the day before -- wasn't available for another half-hour due to federal rules requiring time off between flights.

Ornge has been under fire for months over questionable business deals and sky-high executive salaries that were hidden from public view.

The agency, which is now under a criminal probe for "financial irregularities," is in such disarray that it can't do its job, Klees said.

"This should never happen," he said.

"The fact that the hospital was willing to make the land transfer -- Ornge insists, no, this is now our patient and you have to wait until an Ornge ambulance shows up -- I can tell you, serious, serious problems here."

Klees said he also questions whether Health Minister Deb Matthews really has any sense of how deeply those problems run.

Matthews fired back, saying it's "a big mistake" for a politician to point fingers without having all the facts.

Her ministry, which installed new leadership at Ornge in January, is looking into the incident, she added.

It's unrealistic to expect that Ornge will be able to answer every call it receives, Matthews said. While patient safety is the top priority, sometimes staff just can't send a helicopter due to bad weather or other factors beyond their control.

"So, does Ornge respond to every call? No, it cannot. It cannot respond to every call," Matthews said.

"Do they do their very best to get there whenever they possibly can? Absolutely, and the front-line staff deserve our gratitude."

James MacDonald, a spokesman for Ornge, said the organization is conducting an internal investigation, but can't provide any further comment due to patient privacy.