American Airlines posted its highest revenue of the Covid pandemic during the fourth quarter as bookings rose, but it still reported a loss, as the spread of the omicron variant hurt travel demand.

“Over the past year, we have experienced periods of high travel demand countered by periods of decreased demand due to new COVID-19 variants,” American’s CEO, Doug Parker, who steps down at the end of March, said in an earnings release Thursday. “This volatility has created the most challenging planning environment in the history of commercial aviation.” 

United Airlines on Wednesday and Delta Air Lines last week warned that omicron would delay the travel recovery.

Parker told CNBC’s “Squawk Box” on Thursday that bookings for trips a month or two away are stronger than current levels and that fares would likely rise as business travelers return.

The year was challenging for American and other carriers that tried to ramp up flying but staffing shortages exacerbated routine problems like weather, leading to hundreds of flight cancellations.

American ramped up flight attendant pay for the holidays and offered bonuses to other staff, a measure other airlines took as well, even before omicron-related staffing shortages appeared around the year-end holidays.

American said it hired 16,000 people last year and reiterated its goal to hire 18,000 this year.

The airline had a loss of $931 million in the fourth quarter on revenue of $9.43 billion, which was down from $11.3 billion in sales in the last three months of 2019, before the pandemic. Adjusting for one-time items, American lost $1.42 a share, compared with analysts’ estimate of a $1.48 per-share loss.

For the first quarter, American expects revenue to be off 20% to 22% from the same period of 2019 when it generated $10.6 billion in sales. American projected capacity for the first three months will be 90% to 92% restored.

American’s shares were up slightly in morning trading.

Here’s how American performed in the fourth quarter compared with what Wall Street expected, based on average estimates compiled by Refinitiv:

• Adjusted results per share: a loss of $1.42 versus an expected loss of $1.48

• Total revenue: $9.43 billion versus expected $9.38 billion.