NEW YORK — Lower airfares and rising salaries are putting a squeeze on Delta Air Lines.

Luckily for the airline, the price of jet fuel remains cheap and the Atlanta-based carrier was able to report Thursday a third-quarter profit of $1.26 billion, down 4 percent from the same period last year.

Summer is typically the strongest period for U.S. airlines and Delta’s earnings could signal and end of an extraordinary run of record profits for the industry. The issue is that this era of cheap fuel isn’t going to last forever.

Delta paid $1.50 for each gallon of jet fuel in the quarter, down from $1.89 during the same period last year. Every penny per gallon saved adds up with the airline consuming 1.1 billion gallons of fuel during the quarter. Delta warned in its earnings release that, for the first time in several years, year-over-year fuel prices will be higher in the next quarter.

At the same time, the industry is struggling with too many seats in the sky, lower airfares and increased costs for most non-fuel expenses including salaries and payments for new aircraft.

The amount of money Delta collected for each mile that each available seat flew plunged 6.8 percent during the three months that ended Sept. 30.

The average airfare for each 1,000 miles passengers flew during the summer was $153.80, down 5.3 percent from the $162.40 Delta collected during the same period last year.

The number of available seats and the miles they flew increased 1.5 percent while the actual flying by paying customers fell 0.2 percent. A year ago, 86.8 percent of Delta’s seats were filled with paying passengers during the peak July, August and September quarter. That fell this year to 85.4 percent.