Portuguese airline TAP, partially privatized by the government in 2015, said it’s preparing for an initial public offering.

The carrier, part-owned by airline tycoon David Neeleman, is readying itself for a sale but can’t be sure when that might be, Chief Executive Officer Antonoaldo Neves said at a press conference in Lisbon on Friday.

“We’re preparing the company so that when TAP has to do the IPO it will carry out the IPO,” he said. “It’s very hard to determine the timing.” Neves declined to specify how much of TAP might be sold off, while adding that it’s normal for companies to offer 15 to 30 percent of their shares in a flotation.

TAP plans to lift its annual passenger count to 20 million within five years from about 16 million now as it adds 70 new planes to expand its network and save on fuel. The carrier posted a loss of 118 million euros ($133 million) last year from a profit of 21 million euros in 2017 as it booked restructuring costs, signed union deals and saw its expansion held back by delays at Airbus SE.

Neeleman, who owns a 45 percent stake in TAP through the Atlantic Gateway venture with Portuguese investor Humberto Pedrosa, said at the briefing that the airline partly needs to float because of its 600 million-euro debt burden with banks, though it generates sufficient cash to meet its obligations.

“To strengthen the company and to make sure we’re covered for the good and the bad years, we have to at some point in time go public,” he said. TAP may be in shape for an IPO next year, though that doesn’t mean it will go ahead with a sale in 2020 as the market needs to be right, he added.

Earnings are being held back by issues with the fleet, Neeleman said, citing the late delivery in November of the first Airbus A330neo, for which TAP was the global launch customer, and A321neoLR narrow-bodies. Next year should be better as more planes arrive, he said.

Portuguese state holding company Parpublica owns 50 percent of TAP, according to the carrier’s website.