United Airlines Holdings Inc. warned that sales won’t exceed half of last year’s levels until there’s a vaccine for the new coronavirus.

“Our best guess is demand, as measured by revenue, will recover over time to be down approximately 50 per cent and then plateau at that level until a vaccine is widely distributed,” Chief Commercial Officer Andrew Nocella said Wednesday on an earnings call with analysts.

The downbeat projection points to the limits of any short-term rebound for airlines as the industry grapples with an unprecedented travel collapse because of the coronavirus pandemic. United late Tuesday reported an adjusted loss of US$2.6 billion for the second quarter, which the carrier described as “the most difficult” in its 94-year history.

Neither Nocella nor Chief Executive Officer Scott Kirby would guess when the airline might reach that 50 per cent milestone. The Chicago-based carrier expects a relatively quick travel recovery whenever a vaccine is widely available.

United expects to burn US$25 million a day in the third quarter, down from US$40 million in the second, as the airline braces for a choppy recovery.

More than 6,000 employees have agreed to leave the company in its effort to cut costs, United said. Another 26,000 have accepted various temporary leave offers. The company this month warned 36,000 workers that their jobs would be at risk when federal payroll aid expires at the end of September.

United fell 3.5 per cent to US$31.92 at 1:59 p.m. in New York while other carrier stocks were little changed. The airline’s shares tumbled 62 per cent this year through Tuesday, the biggest drop on a Standard & Poor’s index of major U.S. airlines.

Demand for flights collapsed in March and April because of the coronavirus, and the U.S. government stepped in with US$25 billion in assistance for the nation’s airlines.

United is bolstering its cash position and said it would have more than US$18 billion of liquidity by the end of the third quarter. The company has raised US$16.1 billion since the start of the pandemic and can borrow another US$4.5 billion from the federal government later this year if necessary.

Delta Air Lines Inc. last week reported a record loss in the second quarter. American Airlines Group Inc. and Southwest Airlines Co. report earnings Thursday.

United remains cautious about adding flights, with third-quarter seating capacity set to be about 35 per cent what it was a year earlier. Its plans in part reflect deep declines for international travel, which typically is a bigger market for United than for its U.S. rivals.

The company said it would “tilt” some capacity to leisure destinations and areas with strong family travel patterns. It will continue to review and cancel flights on a rolling 60-day basis “until it sees signs of a recovery in demand.”