The carrier's planes were 69.7 percent filled, up from 65.7 percent last year, mainly because of the reduced service. Bigger plane loads tend to be more cost-efficient for airlines.
Major carriers are adding back service because the US economy is improving and airlines are entering the busy summer travel season when traffic levels are expected to be 3 percent to 7 percent below last year, said ABN Amro analyst Ray Neidl. That's true for United though it's lagging rivals, he said.
Bringing back workers will beneficial to the carrier and helps build employee confidence in Chairman and Chief Executive Officer John Creighton, analyst Denney said. Creighton, who was previously just a UAL board member, took the company's top slot late last year.
That's a crucial part of improving service and bringing back customers to an airline that has struggled with labor issues in the past two years, he said.
United still has "the dominant route network, they've been failing on execution in the past two years," Denney said.



