Boeing Co., which has almost doubled its capacity to turn passenger jets into freighters since the pandemic began, is considering adding even more as demand for air cargo extends into 2022.

“There could be additional lines in the Asia region,” Ted Colbert, head of Boeing’s global services division, said during an interview with Bloomberg at the Singapore Airshow Tuesday. “I see that as a strong place of demand, without a doubt.”

Boeing’s total lines worldwide that convert traditional aircraft into freighters have jumped to 22 from 12 since Covid decimated passenger traffic, Colbert said. Seventeen lines are for Boeing 737s and five are for 767s, he said.

Airlines are relying more on their cargo businesses to replace lost income. Demand for freighters has surged because so many passenger jets—which also carry cargo in their hold—aren’t in service because of the pandemic.

The International Air Transport Association said last month that global cargo capacity was still constrained, driving up the price of air freight. In December 2021, rates were almost 150% above 2019 levels, IATA said.

Cathay Pacific Ltd., whose passenger business has been badly hurt due to Covid considering it has no domestic market, said last month it may report a second-half 2021 profit of between HK$1.5 billion ($192 million) to HK$2 billion with cargo the key bright spot. Korean Air Lines Co. reported a third-quarter profit of $370 million buoyed by robust freight sales.

Colbert declined to say how many conversion lines Boeing is considering adding. “I wouldn’t say it’s a large number right now,” he said. “We do not want to overcapacitize this market.”