DALLAS (AP) — Cheaper jet fuel thanks to falling oil prices helped Delta Air Lines earn $980 million in the fourth quarter despite lower revenue than a year ago.

The results fell slightly short of Wall Street expectations.

Delta officials said demand for travel remained solid, but they forecast another decline in a key revenue measure through the first three months of 2016. That could add to investor concern that airlines will add too many flights and cut fares while fuel is relatively cheap.

Delta expects to pay about $1.20 to $1.25 per gallon for fuel in the first quarter, an even better deal than the $1.85 it paid in the fourth quarter.

Including Delta Connection regional flights, the company saved nearly $2.8 billion or nearly 65 percent on fuel, compared with late 2014. The airline now spends less on fuel than it does on labor — the cost of salaries and benefits rose 9 percent to become Delta's largest single expense.

Atlanta-based Delta's net income for the fourth quarter contrasted with a loss of $712 million a year earlier, when the airline took a $1.2 billion write-down in the value of fuel hedges, which provide insurance against rising energy prices but cost money when oil prices fall. Delta's fuel-hedging loss was a far smaller $54 million in the fourth quarter of 2015.

Excluding what it termed one-time items, Delta said it would have earned $1.18 per share. On the same basis, analysts surveyed by Zacks Investment Research and FactSet expected $1.19 per share.

Revenue fell 2 percent to $9.50 billion, which Delta blamed on losses due to currency exchange rates. FactSet said analysts expected $9.61 billion.

Passengers flew more miles but paid about 2 percent less per mile because of lower average fares. Delta forecast that the per mile figure — a closely watched indicator of demand and average fares — would fall again, by between 2.5 percent and 4.5 percent, in the first quarter of 2016. Company President Ed Bastian blamed international volatility and currency rates.

"The overall demand environment remains solid." Bastian said in a statement. He said the airline's size would let it focus "on those areas of the business with the best opportunity such as the domestic marketplace, while reducing our exposure in some weaker international regions."

Some analysts believe airlines will try to reassure worried investors by curtailing growth plans for 2016 rather than use cheap fuel to flood the market with more flights.

"The airlines will continue to benefit from lower jet fuel costs as they were profitable with oil up to $114 per barrel and are clearly quite profitable at current levels, even with (fare) discounting," Helane Becker, an analyst with Cowen and Co., said in a note to clients.

For all of 2015, Delta earned $4.5 billion on revenue of $40.7 billion. It paid employees $1.5 billion in profit sharing and gave shareholders $360 million in dividends and spent $2.2 billion to buy back its own stock, making remaining shares more valuable.

Airline stocks have performed more poorly than the broader market so far in 2016. At Friday's closing price, Delta Air Lines Inc. shares were down 12 percent this year, and the Arca index of airline stocks was down 14 percent, compared with a drop of 8 percent in the Standard & Poor's 500 index.