Twenty years ago, David Hoback had a bird's-eye view of the chaos and devastation wrought by the Roanoke Valley's worst flooding on record.

A volunteer firefighter at the time, Hoback spent the afternoon of Nov. 4, 1985, aboard a U.S. Coast Guard helicopter, rescuing people from the rooftops where they had been trapped by raging floodwaters.

"Nobody had a clue this was coming," Hoback said.

Today, as the acting chief of the Roanoke Fire-EMS Department and the beneficiary of 20 years of hindsight, Hoback has a different view of how the Roanoke Valley's first responders would handle a flood like the one in 1985, which caused more than $100 million in damage and killed 10 people.

"We can't stop the water from rising and falling," he said. "But we certainly can make preparations to prevent property loss and the loss of life."

Since 1985, the region's flood response plans have undergone major improvements:

* A sophisticated flood warning system is now in place. More than 30 gauges measure rainfall accumulations and creek levels in Roanoke and Montgomery counties, automatically feeding the information every 15 minutes to the National Weather Service in Blacksburg. There, officials crunch the data in a computer system designed to spot a flood in the making.

* When a flood warning is issued in Roanoke, officials will implement the city's new Reverse 911 system. The computer software will dial every number in the affected areas and play a recorded message informing residents of potential flooding and telling them what to do.

* Once the high waters arrive, Hoback said, rescue officials are now better trained and have far more tools at their disposal, such as improved radio communications and swift-water rescue teams.

But despite all the advances made over the past two decades, officials concede they would still be scrambling today to deal with the weather of Nov. 4, 1985, which dumped 6.6 inches of rain in 24 hours over a region already saturated by heavy rainfalls the preceding week.

But now, they say, they would see the disaster coming and be better prepared to deal with it.

In 1985, by comparison, the National Weather Service did not expect a low-pressure system from the remnants of Hurricane Juan to cause much of a problem in the Roanoke Valley.

A flood warning for the area was called off the morning of Nov. 4. Residents in low-lying areas went about their daily routines. The emergency services coordinator in Salem wore a suit and tie to work. Most of the city's firefighters made plans to attend a funeral for two colleagues killed in the line of duty several days earlier.

Then the weather system stalled. "I had never seen it rain like that," then Roanoke assistant city manager Bob Herbert said of the unrelenting deluge.

By the time new flood warnings were issued, people who never heard them were stranded on rooftops and in buildings that had become islands.

The odds of such a scenario repeating itself have since been reduced by the implementation of IFLOWS, or the Integrated Flood Observing and Warning System. The system relies on radio transmissions from automatic rainfall gauges scattered around the valley and devices that measure the levels in tributaries such as Mason and Tinker creeks.

Whenever there's a heavy rainfall, "We have lots of alarms that go off, different things beeping," said Peter Corrigan, a hydrologist at the National Weather Service in Blacksburg. Corrigan and his co-workers take the rainfall amounts and creek levels that are updated four times an hour and analyze the data with other variables, including ground saturation and projected rainfalls from the latest radar readings.

"We're so far ahead of 1985 in terms of rainfall estimates, with radar," Corrigan said. "That alone would have made a huge difference."

Joe Coyle, who was Roanoke's emergency management coordinator before taking a job with the state earlier this month, says IFLOWS can tell officials what is happening at 8 a.m. at the Roanoke River's headwaters in Montgomery County, which in turn gives them a pretty good idea of what to expect by 2 p.m. in downtown Roanoke.

"It allows us to do a lot of things proactively, where 20 years ago we would just be guessing," Coyle said. For example, officials can use the warning system to activate swift-water rescue teams in Roanoke and Salem, positioning personnel trained in rescue operations in the places they might be needed most.

Although IFLOWS has already played a key role during floods, city officials have yet to implement the Reverse 911 system. The city is encouraging residents without land lines to provide their cellphone numbers for the system, which will also be used in the event of gas leaks, terrorist attacks or other natural disasters.

Even with the best warning system available, it's inevitable that rescue workers will still be called on by people caught in the high waters. To that end, Hoback said, firefighters and paramedics have learned valuable lessons since what he called the "makeshift rescue operation" of 1985.

Some of the lessons are as basic as not having firefighters work a flood in heavy turnout gear and boots that can become deadly anchors in a hard current. Other training and education is more specialized, such as that provided to members of swift-water rescue teams in Roanoke, Salem and Bedford County.

And with the Roanoke River prone to retreat as swiftly as it advances, sometimes the trick is knowing when not to take unnecessary chances to rescue people who are not really in danger, Hoback said.

"We took a lot of risks we didn't need to," Hoback said, recalling people dangling in harnesses as they were pulled through the air to the waiting helicopter. "When you go back and look at it, we're lucky we didn't lose anybody."

Even with risks identified and plans in place, chaos can still break out -- as evidenced by the botched response to Hurricane Katrina in New Orleans. That was one reason Roanoke City Council recently called for a comprehensive study of the city's entire emergency response system.

The idea, acting assistant city manager Jim Grigsby said, was partly to look at the lessons learned in New Orleans and ask: "Do they apply to us and our plan? We don't want to have a document just sitting on the shelf, where you pull it off once a year and blow the dust off it."