The US carrier reported a pre-tax profit of $494 million for the three months to the end of March, down from $511 million in the previous year.
Revenue was down 4.8% year-on-year to $8.2 billion. Fuel costs fell 34.7% to $1.2 billion.
Meanwhile, parent company United Continental Holdings has reached an agreement with two of its investors over new board appointments.
Two people proposed by Altimeter Capital Management and PAR Capital Management, who collectively own 7.1% of the airline group, will join the board with immediate effect.
The newcomers are Edward Shapiro, managing partner and portfolio manager at PAR, and Barney Harford, former chief executive of online travel agency group Orbitz Worldwide.
The appointments follow three others last month, meaning that at the 2016 annual meeting half of the 14 directors will be new to the board as of March 1.
“When taken together with substantial changes the board independently has adopted... the addition of the two new directors designated by Altimeter and PAR will transform our Board governance," said chief executive Oscar Munoz.
Both PAR and Altimeter had previously been critical of United’s performance.
Shares in United closed down 4.6% at $52.76.
