CHICAGO  The parent company of United Airlines, the UAL Corporation, reported a $537 million loss in the first quarter on Tuesday, bigger than expected, as a 51 percent increase in fuel costs overwhelmed furious efforts to raise fares at the country’s second-largest carrier.

UAL shares closed down $7.88, to $13.55.

Unless oil prices unexpectedly retreat, there is no relief in sight for airlines, and nearly the entire industry is expected to lose money this year.

United, based in Chicago, plans to reduce employment by 1,100 by the end of the year, as airlines begin a new round of layoffs. United increased the number of planes it plans to shed to 30, from an earlier estimate of 15 to 20, in hopes of constraining capacity and driving fares up further.

JetBlue Airways and AirTran Holdings, two formerly fast-growing discount carriers, also posted first-quarter losses. JetBlue, which operates from John F. Kennedy International Airport in New York, reduced its growth plans for the year, hoping to keep raising fares.