Health Minister Erin Selby said a woman was transported to Winnipeg for medical care on Nov. 28 following a heart attack.
The patient died shortly after landing in Winnipeg even though the flight was fully staffed with two pilots, a doctor, a paramedic and a critical care nurse, Selby said.
The case and 15 others are now under review by an external auditor and the use of the Shock Trauma Air Rescue Service has been suspended until "issues of concern" are resolved, she said.
"Families in Manitoba deserve safe, effective, quality emergency services and make no mistake, we know that this helicopter ambulance plays a vital role in our health-care system," Selby said Monday at a press conference.
"This was not a decision that was taken lightly."
In May, a two-year-old boy was left brain-damaged following a flight from Brandon to Winnipeg for medical treatment.
Morgan Moar Campbell was placed in a medically-induced coma, which required insertion of a breathing tube prior to the helicopter flight with STARS.
The tube was discovered dislodged when the chopper landed in Winnipeg and the toddler ended up in pediatric intensive care.
Another previously unreported critical incident in February also involved a patient who was not provided with sufficient oxygen.
Although the province brought together experts following the first incident to review the case and draw up some conditions for future flights, the head of health emergency management said it doesn't appear that those conditions were being followed.
"It's clear, based upon this third critical incident, that basic medical practices and basic medical advice appears not to have been followed," said Gerry Delorme, with Manitoba Health.
This is the first time STARS, which operates in Manitoba, Saskatchewan and Alberta, has been suspended.
The province will rely on its own fleet of 24 air ambulances and two jets during the suspension, Selby said. She couldn't say how long the suspension will last, but said the results of the review will be made public.
"We plan to get this right," she said. "We're not going to rush it. We will wait until we get that review and make decisions at that point."
Colin Fast, a spokesman for STARS, said the non-profit service, which gets $12 million from the Manitoba government a year, has a "culture of safety" and is co-operating fully with the review.
"We look forward to working with the government on this review and we're fully confident in the ability of our physicians, our nurses and our paramedics," he said.