Delta Air Lines closed out the year by doubling its quarterly profit as travel demand, particularly for international trips, helped drive record revenue in 2023. CEO Ed Bastian said continued strong travel demand could boost earnings this year.

Still, the company’s full-year profit outlook was below a previous forecast, and the stock fell 5% in premarket trading.

The airline on Friday forecast adjusted earnings per share of between $6 and $7 for 2024, below the more than $7 a share the carrier predicted last year. Delta posted adjusted earnings of $6.25 a share in 2023.

“Business is going great. Just go to any airport,” Bastian told CNBC in an interview.

Delta said it expects revenue in the first quarter of 2024 to increase 3% to 6% over the prior year period. The carrier forecast earnings per share of between 25 cents and 50 cents, within the range analysts are projecting, according to LSEG, formerly known as Refinitiv.

The winter is typically one of the slowest periods for air travel. Airlines have also been navigating cooling fares and higher expenses like fuel and labor.

Delta is the first of the major U.S. carriers to report fourth-quarter results.

Here’s how the company performed in the three months ended Dec. 31 compared with Wall Street expectations based on consensus estimates from LSEG:

• Adjusted earnings per share: $1.28 vs. $1.17 expected.
• Adjusted revenue: $13.66 billion vs. $13.52 billion expected.

Delta reported $2.04 billion in net income for the last three months of 2023, up from $828 million a year ago. Revenue rose 6% to $14.22 billion from a year earlier.

Stripping out one-time items, Delta posted adjusted revenue of of $13.66 billion, slightly ahead of LSEG estimates. Adjusted per-share earnings of $1.28 topped analysts’ estimates for $1.17 a share in the fourth quarter.

Delta’s president, Glen Hauenstein, said in a news release that the carrier has had strong demand for international travel “and a positive inflection” for domestic travel. Some carriers have struggled with oversupply of domestic flights in recent months, forcing them to discount off-peak fares more than usual.

Delta and other large U.S. carriers have benefitted from offering sprawling international networks, where many high-priced tickets were sold last year. Delta also said that premium revenue from higher-priced seats like those in first class or premium economy continue to lift revenue.

But the carrier still faces challenges with the aerospace supply chain for parts and repairs, Bastian said.

“It’s taking longer to fix planes and taking longer to put them back into service,” he said. Aircraft repairs and the parts supply chain is “the biggest area of the business that’s not returned to a pre-pandemic level of performance.”

The airline industry was rocked in recent days when a door plug blew out of a Boeing 737 Max 9, an Alaska Airlines flight, when the plane was at about 16,000 feet. The Federal Aviation Administration grounded those Boeing planes a day later.

Delta doesn’t have any Max 9s in its fleet, though it does have dozens of 737 Max 10 aircraft, which the FAA hasn’t yet certified, on order. It isn’t yet clear whether the Alaska incident will mean further delays to the certification of the Max 10s.

Delta also announced Friday an expected order for 20 wide-body Airbus A350-1000 aircraft, with deliveries starting in 2026.