Airfares have climbed sharply this year, driven in part by the war in Iran. But Delta Air Lines CEO Ed Bastian says elevated ticket prices may prove durable even if oil prices ease, because travelers keep buying.

Speaking in an interview with CNBC on Friday, the chief executive of one of America's largest airlines said he was surprised that Delta's profits held up through a 60% jump in fuel prices, thanks to resilient demand for tickets. In July, following the airline's second-quarter results, Bastian told CNBC that Delta was passing along 60% of its higher fuel costs to consumers and expected that figure to approach 100% in the third quarter.

"To not dent those profits, to me is incredible," Bastian said in the CNBC interview. He noted that the 60% increase in the airline's jet fuel costs in the third quarter amounted to an extra $1.6 billion. "In past cycles, past shocks, if we saw a 60% increase in fuel prices, we'd be flat on our back."

Delta last week reported $17.6 billion in adjusted revenue for the third quarter, a 16% year-over-year increase that fell just short of analysts' $17.67 billion estimate. The airline spent an adjusted 62% more on jet fuel than in the same period a year earlier, yet its revenue per seat mile—the measure of how much money an airline earns for each seat it flies one mile—rose 15%, reflecting higher fares and strong demand. In other words, fuel spending is rising roughly four times as fast as the revenue generated per seat, leaving fare increases so far only a partial offset.

On the company's third-quarter earnings call, Bastian credited consumers for helping Delta maintain its profits despite the price increases.

"Fuel has been the impetus for the industry to move quickly to adjust the pricing environment. But given the fact that the market has accepted these price points," and given that the company still views airfare as reasonably affordable, Delta's position is very sustainable, he said.

"I think we're going to be fine as you look forward. Hopefully, we will see fuel recede into the next year at some point, and that's when I think you'll see the real earnings power of this franchise be amplified," he said on the earnings call.

The sector's continued strength comes as the average price for domestic trips hit $445.26 in the second quarter, according to the Bureau of Transportation Statistics. Airline ticket prices rose about 23% year over year, according to the U.S. Travel Association.

Skyrocketing Oil Prices

Higher oil prices are partly to blame for the surge in airfares. Oil rallied this year as the war in Iran crippled transit through the Strait of Hormuz, the chokepoint through which 20% of the world's oil flowed before the conflict. Brent crude stood at $108 on Monday, up more than 70% from a year ago.

Airlines are particularly exposed to increases in oil prices. After labor, fuel is airline companies' biggest expense, accounting for roughly 21% of their operating costs as of earlier this year, according to Airlines for America, a trade association and lobbying group.

Because jet fuel prices generally move with oil prices, they rise in tandem, and jet fuel is already up more than 100% compared with a year ago, according to the International Air Transport Association. U.S. Gulf Coast jet fuel cost $4.34 a gallon on Thursday, nearly double the $2.19 of a year earlier, according to CNBC.

Unlike their European counterparts, U.S.-based airlines also do not hedge against rising oil prices, meaning increases are often passed on to the customer. Delta, for its part, bought an oil refinery more 10 years ago through a subsidiary, which helps offset its fuel costs.

Delta was the first major U.S. airline to report third-quarter earnings, but other carriers' chief executives have also noted the industry's sales resilience in the face of rising fuel costs. Southwest Airlines CEO Bob Jordan told CNBC in July, "Despite high fuel and high prices, we're seeing really strong demand."

In prepared remarks during American Airlines' second-quarter earnings call, CEO Robert Isom said, "Consumer spending remains resilient, underpinned by a healthy labor market and a sustained preference for travel relative to other discretionary categories."

With Delta the first major U.S. carrier to report third-quarter results, peers' upcoming numbers will show whether that resilience—and the fare durability Bastian describes—holds across the industry.

Higher fares have not fully shielded Delta from rising fuel costs. The airline last week cut its full-year profit outlook to between $5.10 and $5.60 per share, down from its previous forecast of $6.50 to $7.50. It also missed Wall Street's earnings estimate for the first time in two years.

This story was originally featured on Fortune.com.