The city’s troubled EMS 911 system briefly flat lined this morning, which could have caused delays for people desperately waiting for an ambulance, authorities said.

The software crash happened from 11:10 a.m. to 12:10 p.m. and 350 EMS calls taken during that time period were processed manually, officials said.

Authorities said they do not believe response times were impacted.

“Preliminary indications are this was caused by routine maintenance done on the system today,” said Mark Lavorgna, a spokesman for Mayor Bloomberg.

“Backup systems and procedures immediately went into effect, and 911 calls for EMS assistance were taken and responded to without noticeable delay to the 911 caller, or impacts to response times. The system that briefly failed is now back up and running.”

The system that went down was the EMS Computer Aided Dispatch System, commonly referred to as “CAD,” sources said.

The CAD system is where the call taker enters the data about the call and electronically relays that information to the EMS dispatch team.

Four servers support EMS CAD and routine maintenance had been successfully performed on three of those servers, sources said.

While the fourth server was being serviced, all four servers briefly went down.

EMS CAD was installed in the early 1980s and is set to be replaced as a part of the city’s ongoing, comprehensive 911 system overhaul.

The replacement will cost approximately $40 million, and planning is currently under way.

All the personnel working on the system work off the same floor at the Public Safety Answering Center in MetroTech in Brooklyn, allowing them to communicate quickly.

In this case, EMS call takers manually relayed information to the EMS and Fire dispatchers, who are only a few steps away.

This malfunction was just the latest problem with the city’s beleaguered 911 system, which is currently undergoing a $2 billion overhaul that’ll replace this CAD system.

A report commissioned after the disastrous response to the December 2010 snowstorm uncovered a myriad of problems.

The shortcomings of the system, launched in May 2009, were numerous and resulted in 14 recommendations for improvements included in the report put out by City Hall.

Most centered on the lack of coordination between the Police and Fire Departments in creating what was supposed to be a “unified” response to get emergency vehicles to the scene more quickly.

And it wasn’t the first time the EMS system crashed in recent months.

Last October, the system went down on consecutive days, leaving Emergency Medical Services dispatchers scrambling for pen and paper to take down calls by hand.

Dispatchers fell back on radios to send ambulances out on calls – but had no way of knowing where units were or which ones were available.

“They had to read every job to the units over the radio, and the units had to write everything down in the ambulance. It takes forever,” an EMT who works The Bronx told The Post at that time.

Normally the computer system creates a screen for each call with all the necessary info.