Delta Air Lines shares rose Thursday after the Atlanta-based carrier raised its profit forecast for the year as travel demand continues to climb, particularly for its premium-class cabins. Its CEO said the airline is also benefiting from the grounding of competitors' Boeing 737 Max planes.

Delta expects to earn $6.75 to $7.25 per share this year, up from a previous estimate of $6 to $7 a share. Its stock was up 1.5% in afternoon trading.

Delta doesn't operate the Boeing 737 Max, which has been grounded worldwide since mid-March following two fatal crashes that claimed a total of 346 lives.

"We do not fly the Max and clearly there was a benefit to the airline in the quarter," Delta's CEO Ed Bastian told CNBC's Squawk Box on Thursday, calling the boost "marginal."

Competitors American, Southwest and United have canceled thousands of flights throughout the busy summer travel period and removed the 737 Max from their schedules through the end of the season as the plane remains grounded. Regulators have not indicated when they will allow the planes to fly again.

"It's taken longer than any of us expected to see it return to service," Bastian said. "We don't have a crystal ball on that."

American Airlines on Wednesday said the Max grounding likely cost it $185 million in pretax income in the second quarter, but as a result raised its forecast for revenue per seat mile, a measure of how much an airline is making for every seat it flies one mile, to an increase of 3% to 4% from the April to June period of 2018, up from its previous forecast for growth of between 1% and 3%.

American's flying in the three months ended June 30 fell about 0.8% from the second quarter of 2018, as it had to cancel 7,800 flights, American said. Delta, on the other hand, expanded flying by close to 5% from a year earlier.

Delta's second-quarter profit rose about 30% from a year ago and topped analysts' expectations, as demand for travel, particularly for premium-class cabins and corporate travel drove its earnings higher.

Delta passengers have shown they are willing to pay more for seats on the airline. Travelers are buying 65% and 70% of seats in first class cabins, Bastian said. That's up from about 13% for domestic routes in 2011.

Delta's revenue from premium seats, which include seats with extra legroom and premium economy as well as business and first, rose 10% in the second quarter to $4 billion, twice as fast as revenue from the main cabin, which came in at $5.9 billion.

Delta posted a per-share profit of $2.35, on an adjusted basis, on record revenue of $12.5 billion, which roughly in line with estimates. Higher revenue from premium cabins and corporate travel helped drive sales higher, the airline said. Net income rose to $1.4 billion from $1.04 billion in the April-June quarter of 2018.

Delta expects earnings per share of $2.10 to $2.40 in the third quarter. Analysts expected third-quarter per-share earnings of $2.18.

United Airlines will be the next carrier to report results on July 16. American and Southwest report at the end of the month.