Southwest Airlines' first flights from Hartsfield-Jackson International Airport took off Sunday, with some local travelers giving the carrier a try for the first time to see how it compares with longtime Atlanta carriers Delta Air Lines and AirTran Airways.

Dallas-based Southwest, which acquired AirTran last year in part to gain access to the Atlanta market, launched service from Hartsfield-Jackson to Austin, Baltimore/Washington, Denver, Houston Hobby and Chicago Midway, with a total of 15 daily flights.

The initial flights out of Atlanta were on 137-seat Boeing 737-700s that left only partially full. The first three flights each left with fewer than 50 passengers. Southwest officials pointed to this time of year being a slower period for travel and the ramp up may take time.

Even without full flights, passengers were greeted by enthusiastic Southwest employees clad in yellow shirts reading "Atlanta at Last" who offered refreshments, prizes and gift bags  -- along with tutorials on Southwest's unconventional boarding process and open-seating system. Southwest, the nation's largest low-cost carrier, has all-coach class planes and no assigned seats. It also allows two free checked bags. It has a unique boarding system calling for passengers to line up in an order that's primarily based on when they checked in for their flights.

Julie Boston, a Southwest customer services manager, said staff will be on hand at Southwest gates at Hartsfield-Jackson for the next few weeks to explain how the boarding system works.

Some Atlantans were curious about the newcomer.

Phillip Dumond, who lives in Buford and said he was flying Southwest for a business trip on Sunday, was eager to try the airline.

"I'm kind of excited to fly," Dumond said. A long-time Delta customer up until this year, he acknowledged, "I don't know if Southwest is any better. But at least they communicate they're better."

"I'm just excited to have another option here," Dumond said. "Hopefully they won't disappoint."

Hartsfield-Jackson general manager Louis Miller said the arrival of Southwest brings one of the most financially stable carriers to Atlanta.

"The local Atlanta residents are really the ones that will benefit the most," Miller said.

Atlanta-based Delta, the largest carrier at Hartsfield-Jackson, said it's "business as usual for us." Spokesman Trebor Banstetter said Delta competes with low-cost carriers nationwide, and has a global route network of nonstop flights from Atlanta to nearly 250 destinations, along with first class, assigned seats and other amenities.

AirTran general manager Rick Pelc said nothing changes for AirTran immediately.

AirTran, the second-largest carrier at Hartsfield-Jackson, will continue to operate out of Atlanta in some form for a couple of years. Southwest will add more flights out of Atlanta in coming months, as it prepares to gradually transition AirTran planes to the Southwest fleet. Some travelers say they'll miss AirTran's presence in Atlanta once it is gone, particularly its business class and assigned seats. In the second quarter, the company aims to allow frequent fliers to convert AirTran credits to Southwest points and vice versa, said Southwest's chief marketing officer Dave Ridley.

Lawrenceville resident Brian Gilbert and flew Southwest to Denver on Sunday for a business trip, said he was trying Southwest "as a new thing."

"Delta's always been my favorite," Gilbert said.

But, "every time you fly across the country, you hear about Southwest," he said. "I just thought I'd give them a try. This is their test for me."