Santa Rosa's airport terminal was a quiet spot when Horizon Air first landed five years ago.
The county airport had been without passenger service for more than five years, after United Express halted flights to Sonoma County in 2001.
Horizon started small on March 20, 2007, flying two daily nonstops from Santa Rosa to Los Angeles and Seattle.
Since then it's grown to five round-trips a day, with added nonstops to Portland and Las Vegas. A sixth flight is coming in June.
Now flying under the banner of Horizon's sister carrier, Alaska Airlines, the service has pumped new life into the regional airport. More than 207,000 passengers took Alaska's Santa Rosa flights last year, up nearly 10 percent from 2010.
There are plans for longer runways, a new passenger terminal and other improvements at Charles M. Schulz-Sonoma County Airport. And there's talk of new carriers and destinations, including a critical eastbound connection.
Sonoma County service has paid off for Alaska and Horizon, said Marianne Lindsey, spokeswoman for the Seattle-based airlines, both part of Alaska Air Group.
"We see Santa Rosa as a strong market and very welcoming since we started service five years ago," she said. "The public response to our Santa Rosa flights has been outstanding."
Alaska will launch a new daily flight from Santa Rosa to San Diego on June 5, dropping its service to Las Vegas. It will also add a third flight to Los Angeles four days a week through Aug. 25.
"San Diego is currently booking strong, ahead of LAX, which is already booking ahead of last year," Lindsey said.