A shortage of pilots has caused chaos for thousands of passengers during peak travel season in the region, as cockpit crew complaining of overwork extended a strike at Taiwan’s biggest carrier to a fourth day.

Since the pilots’ union of China Airlines Ltd. decided to stay away from work starting early Feb. 8, the carrier has scrapped more than 60 flights, including 26 for Monday, taking the total to 10 percent of its scheduled operations, according to Jason Liu, a spokesman for the company. The airline has lost NT$78 million ($2.5 million) in sales after 60 services from Feb. 8 to 10 were cut, according to a regulatory filing.

Citing fatigue, the union is demanding more pilots be assigned to long-haul flights, while China Airlines says it doesn’t have enough cockpit crew, leading to a break down in talks between the parties over working conditions. While the carrier has said more than half of its about 1,400 pilots have reported to work as of Monday, another meeting to sort out the issue is scheduled to be held at 5 p.m. Monday, according to Liu.

The strike and the ensuing cancellations at the Taiwanese carrier—while the Lunar New Year holidays were winding down—also underscore the paucity of skilled air crew in the Asia-Pacific region, where travel demand is set to double in the next two decades. Boeing Co. forecasts about a quarter of a million new pilots will be needed over the period in this region as 40 percent of the world’s fleet is expected to be delivered to Asian carriers.

Flights affected by the strike so far include those between Taipei and Hong Kong—the world’s busiest international air route—as well as from Taipei to Bangkok, Gatwick, Rome and Vienna, according to China Airlines’ website.

Taiwan’s Transport Ministry, which controls about 35 percent of the island’s biggest carrier by fleet, has called on the management to reflect and initiate reforms. This year’s Lunar New Year holiday in Taiwan began Feb. 2 and ended Sunday.

Shares of China Airlines tumbled as much as 6 percent Monday in Taipei, their biggest intra-day loss in a year.

China Airlines was last beset by industrial action in June 2016 when flight attendants went on strike to protest their working conditions. That cost the carrier’s president his job with the government installing a new top management in the wake of the disruption.