The chief executive of American Airlines said that he is assuming that oil at $75 per barrel is the "new reality".
Earlier the company warned that profits would fall this year due to higher fuel, which have been driven higher by the rising cost of crude oil.
However, Doug Parker said he is "confident" that revenue will grow in 2019 and beyond.
American Airlines has endured "the most challenging quarter" since it merged with US Airways five years ago, according to its chairman and chief executive.
Net income fell by 34.5% to $566m (£429m) on revenues up 3.7% at $11.6bn in the three months to June.
American Airlines chairman and chief executive Doug Parker, said: “This was perhaps the most challenging quarter for the American team since our merger with US Airways in 2013.
He said: "Higher fuel prices increased our expenses by more than $700m versus last year and our revenues, while increasing, have begun to trail the rate of increase at our largest competitors for the first time since early 2016.
"Because fuel expenses are expected to increase by more than $2bn this year, we expect 2018 earnings to be lower than last year."
American Airlines updates its policy on therapy animals, and bans tusked animals from flying.
Read moreA man accused of groping a passenger refused to leave and wrestled officers who tried to remove him.
When Jacob Garcia was accused of groping a passenger he refused to leave his American Airlines flight in Miami. The police were called to remove him and a struggle ensued.
American Airlines wrongly accused two professional basketball players of stealing first class blankets.
Read moreBette Nash is celebrating 60 years working as cabin crew and says she has no plans to retire.
Dave Lee
North America technology reporter
Computer glitch at American Airlines gives too many pilots time off over the Christmas break.
Read more
The NAACP warns African Americans could experience "disrespectful" treatment from the airline.
Read more