Airlines have touted how much-dedicated cargo flying they're doing with transformed passenger planes, but United Airlines is the only major U.S. carrier where cargo is boosting the bottom line during the COVID pandemic.

United's second-quarter earnings last weekincluded an eye-popping 36.3% increase in cargo revenue to $402 million. Cargo-ton-miles were up 40.3% to 496 million. Even more impressive is the fact that cargo revenue represented 27.3% of the company's total operating revenue compared to 2.6% in the same period last year. Half-year results showed cargo revenue grew 14.6% to $666 million.

"Our commercial team has done a better job, I think than any airline in the entire world recognizing what the pandemic has meant for demand and taking advantage of opportunities where they present themselves," CEO Scott Kirby boasted. "Our cargo team, led by Jan Krems, [generated a] 36% increase in cargo. I mean, who would have ever thought we could do something like that?"