On Tuesday the carrier beat forecasts for the first quarter - and predicted stronger-than-expected earnings for the current period.
United says it's seeing robust demand for domestic and transatlantic flights, and a pickup in corporate travel spending.
But it faces a big shortfall in the delivery of new jets from Boeing.
The planemaker has been in turmoil since the midair blowout on one of its 737 MAX 9 jets in January.
The Federal Aviation Administration has since capped output of the planes while Boeing takes steps to address quality control.
However, Reuters has reported that the firm is failing to hit even the 38-per-month limit.
Watchdogs also grounded MAX 9s for a while following the blowout, sparking chaos for big operators like United.
It says the disruption cost it $200 million during the first quarter.
Over that time, the airline received just seven new planes from Boeing - way down on the 23 it got a this time a year ago.
Those delays left it overstaffed with pilots, with United subsequently pausing hiring as a result.
The January incident also raised doubts over regulatory approval for the new MAX 10 variant - which was due to be a cornerstone of United's fleet.
It's now converting some orders to other models, and considering what to do about the rest.
Chief Executive Scott Kirby has been a vocal critic of the problems at Boeing, and has reportedly opened talks with Airbus over placing a big order for its jets instead.
