DENVER -- Management problems at Denver Health are resulting in ambulance delays that are endangering patients' lives, a two-month CALL7 Investigation found.

Current and former paramedics, dispatchers and firefighters talked to CALL7 Investigator Tony Kovaleski about the problems that they say are putting patients at risk.

"People absolutely are waiting for ambulances longer than they should," said one paramedic who asked to be anonymous for fear of retaliation at work.

"It's as bad as I have ever seen," another long-time paramedic said.

A series of problems -- including understaffing, not enough ambulances, repeat calls from people who do not need emergency services and poor management -- are causing Denver Health to repeatedly arrive late at emergency scenes, the paramedics and dispatchers said.

"People can be waiting for 12 to 15 minutes for an ambulance. Sometimes it can even be longer than that," a paramedic said. "Sometimes in Denver you would be a lot better off driving yourself to the hospital."

Records obtained by 7NEWS back up the paramedics' claims.

Denver Health's contract with the city includes a goal of having an ambulance arrive in less than 9 minutes on an emergency scene after 911 is dialed. Denver Health has told the city -- and city officials have accepted -- that the hospital will meet that standard only 85 percent of the time, which is below the national standard.

Over the past two months, paramedics failed to meet that goal 12 percent of the time or on 1,100 calls, records show.

According to records obtained under state open records laws there were 88 calls that exceeded 20 minutes, including calls that took 24:57, 26:15 and 26:33.

Hospital officials refused to provide a number of records or said that it would take hundreds of hours and thousands of dollars to produce other documents.

However, Dr. Chris Colwell, medical director of the Denver Health EMS System, said that Denver has one of the best outcomes for patients who use Denver Health ambulances.

Despite Denver Health denying records on deaths associated with delayed ambulance response, Colwell said he reviews every case where a patient dies after an ambulance takes longer than 8:59 to respond.

"If you don't meet the city's standard of 8 minutes 59 seconds and an individual dies from a cardiac arrest -- should you know about that?" Kovaleski asked.

"Yes," Colwell answered.

"Should you know about every one?" Kovaleski asked.

"Yes," Colwell said.

One big problem is that ambulance shifts are not filled. Records show that during shifts over the past two months, managers have elected to cancel or not fill five or more paramedic or EMT units.

Another problem is the people who repeatedly call to get a ride to the hospital even though they do not have an emergency. Paramedics and doctors call them "frequent fliers," and paramedics say their calls may cost someone who has a real emergency his or her life.

"It happens every single day. I've seen some people hundreds of times," one paramedic said. "We probably take six to 12 people to the hospital every single night just because they know the right things to say."

Sources say management has identified more than 200 "frequent fliers" but top Denver Health officials have failed to do anything about the problem.

Colwell said he has worked with social services agencies and at-home medical providers to try to mitigate the problem, but he admits it is a difficult issue to control.

"I do agree it's a very difficult aspect to manage, and I do agree it has impact on the system," Colwell said.

"Would you agree you could do a better job?" Kovaleski asked.

"No, I would not agree that there is something clear we should be doing better," Colwell answered.

Paramedics disagree.

"Have you witnessed where these non-emergency calls have led to delays in real emergency calls?" Kovaleski asked.

"Absolutely, it happens on a daily basis," one paramedic said.

Denver Health must answer to the city for its response times because it has a contract to provide emergency services to Denver residents.

Council President Michael Hancock said he will send Mayor John Hickenlooper a letter asking him to review the ambulance response system.

"It's inexcusable. There's no excuse for not getting to where you need to be to serve a person who needs assistance," he said. "I think there needs to be a wholesale review of our EMS system."