Southwest Airlines said Monday that it will start flights from Charlotte next year, replacing AirTran, but an aviation expert said the small number of flights offered likely won’t have a serious impact on fares at Charlotte Douglas International Airport.

Southwest agreed to acquire AirTran in 2010 for $1.4 billion worth of cash and stock, and closed the transaction last year. The airlines have been integrating their operations since then.

Currently, AirTran flies seven daily nonstop flights from Charlotte to Atlanta and Baltimore. AirTran’s final day of flights from Charlotte will be April 13.

On April 14, Southwest will begin six daily nonstop flights to Baltimore/Washington International airport, Chicago’s Midway airport, Houston’s Hobby airport and Orlando.

“Southwest Airlines is known throughout the country for its unique product and customer service delivery. I am sure this will please a number of our passengers who have been requesting this for some time,” said Jerry Orr, Charlotte Douglas International Airport’s aviation director.

Aviation analyst Fred Lowrance, with Avondale Partners, said Southwest has made an impact on major carriers in other AirTran markets it’s taken over, by offering steep sales to lure new customers. Lowrance said it hurt Delta Air Lines in Atlanta, which was formerly AirTran’s main hub.

But the effect was short-lived, Lowrance said.

“You might have a month of disruption. They’ll do it just to say, ‘Yeah, we’re here,’ ” said Lowrance. “Once that wears off, they’re going to have to get down to the business of covering their cost of flying those routes.”

Southwest is offering one-way fare sales as low as $69 on its new Charlotte routes. They must be booked by Oct. 28, for travel between April 14 and May 22.

US Airways is the dominant carrier at Charlotte Douglas, with about 90 percent of the airport’s more than 700 daily flights. With so many flights from Charlotte Douglas, customers aren’t likely to see a large effect from the six Southwest flights that replace what was already a low-cost carrier.

“In the grand scheme of things, when you think about how many flights leave from CLT each day, it’s probably not that big a deal,” Lowrance said.

Southwest’s schedule for Charlotte, which runs through May 31, drops the Charlotte-Atlanta flight AirTran offered.

Federal data shows Charlotte has the 18th-highest average fare among the nation’s top 100 airports. The average domestic fare from Charlotte was $428 in the first quarter of 2012, up 9.3 percent from the same quarter last year.

Southwest is third in domestic market share, with 15.6 percent, government statistics show. US Airways is fifth, with 8 percent.

Last week, Southwest reported that it swung back to a third-quarter profit of $16 million, up from a $140 million loss during the same period a year ago. Revenue remained flat and ticket prices actually sank slightly, however.