Southwest Airlines flights to Hawaii continue to perform “tremendously successful right out of the gate,” according to one executive. The Dallas-based airline has been hyping service to Hawaii for years, but the level at which the market has responded to Hawaii flights has surprised even the company. “We are performing, I would say, actually ahead of our expectations,” Tammy Romo, chief financial officer of Southwest Airlines Co. (NYSE: LUV), told a crowd at the Cowen Global Transportation Conference on Wednesday.