Environmental concerns are one of several factors driving up airfares.
Taipei has agreed to resume flights to multiple cities across China, saying it hoped this might help improve ties. Reintroducing the flights will make the situation more comparable with the pre-coronavirus norm.
Several domestic flights headed for St. Petersburg had been turned back to their destinations. News outlets reported that it was because an unidentified object had been spotted in the sky.
Around 300 flights that were scheduled to take off and land at the Berlin airport on Wednesday were cancelled. It is the first time since 2018 a labor strike led to so many flight cancellations.
Air traffic operations were gradually returning to normal, the Federal Aviation Administration said, after a systems failure grounded thousands of flights on Wednesday morning.