Trying to gauge the rebound in air travel? Watch United Airlines CEO Scott Kirby. A year ago, Kirby, then the Chicago-based airline’s president, was perhaps the most pessimistic airline chief about the Covid-19 pandemic, warning investors at a J.P. Morgan industry conference in March that the carrier was preparing for a sharp drop in revenue.

The declines surpassed even Kirby’s expectations. U.S. airlines lost a combined $35 billion last year.

After Congress approved each of two rounds of government payroll support last year Kirby and other United executives warned about challenges ahead. After Congress approved a third round of payroll aid last week, Kirby appeared to take a more optimistic tone, saying in a LinkedIn post that “our teams will be able to remain current in their training and ready to match expected future demand.”