[caption id="attachment_47423" align="alignright" width="358"] Alaska Air currently serves Santa Rosa with Bombardier Q400 turboprop aircraft.[/caption]

SANTA ROSA -- Passenger volume at Charles M. Schulz--Sonoma County Airport increased 4.7 percent in September from a year before and was 3.5 percent ahead of the year-to-date pace from 2011, according to the latest figures.

It was the highest level of airline traffic for the first nine months of the year in Santa Rosa since commercial airline service returned in 2007, according to Alaska Airlines, the airport's only airline.

In the first three quarters of 2012, airline volume totaled 159,991, compared with 154,618 in the same period last year.

A total of 19,348 passengers used the airport in September, compared with 18,485 in September 2011.

Seattle-based Alaska Airlines, through its subsidiary Horizon Air, operates five flights a day from Santa Rosa to Portland, Seattle, Los Angeles and San Diego. In June, Alaska Airlines started flights between San Diego and Santa Rosa, replacing service from Sonoma County to Las Vegas.