The Chicago-based carrier also lifted the forecast for adjusted operating margin on the back of improvements in non-fuel operating costs.

United now expects total operating revenue in the quarter through September to be up 12% from the same period in 2019, up from a prior forecast of 11%.

U.S. carriers have been witnessing the strongest travel demand since the pandemic. Over the four-day Labor Day weekend, 8.76 million passengers made their way through U.S. Transportation Security Agency (TSA) checkpoints, surpassing 2019 levels.

However, staffing gaps have made it tougher for the industry to keep up with booming demand. U.S. airlines trimmed summer capacity by 16% to avoid disruptions.

United said it has seen "improving operational reliability" over the course of this year.

It expects its capacity in the current quarter to be better than its previous estimate. Non-fuel operating costs for the third quarter are forecast to be up 16% from the same period in 2019, a slight improvement compared with its previous forecast of 16%-17%.

As a result, the company expects adjusted operating margin for the quarter to improve to 10.5% from 10% projected earlier.

Shares of the company rose 1.4% in premarket trading.