A United Airlines plane seen at the gate at Chicago OHare International Airport (ORD) on October 5, 2020 in Chicago, Illinois.

Daniel Slim | AFP | Getty Images

United Airlines shares fell more than 5% Tuesday morning after the airline reported its fifth straight quarterly loss, and its CEO was unsure about when two key parts of the business would recover from the pandemic.

CEO Scott Kirby said the demand for long-haul and business international travel had declined by about 80% compared to 2019, depriving the airline of high-paying customers it relied on before the pandemic.

“The big question is when those two things will come back and we’re not sure when that is,” Kirby said in an interview with CNBC’s Squawk Box. He said both segments are expected to recover in the summer and the second half of the year.

The airline reported a $ 1.4 billion loss for the first quarter on Monday and said it could achieve profitability even if demand for long-haul and business international travel returns to 35% of 2019 levels.

Demand for domestic vacation travel in popular vacation destinations like beaches has surpassed 2019 levels, Kirby said.

Vacationers flying within the US have spearheaded the recovery of travel as more people are vaccinated, governments relax travel restrictions, and tourist attractions reopen. But companies still haven’t got many of their employees back on the streets, and international travel bans or quarantine requirements continue to keep many travelers closer to where they live.

“I don’t know how people find hotels,” said Kirby.