MANILA -- None of the 25 pilots who resigned from the country's flag carrier, Philippine Airlines, have returned to work despite the ultimatum given to them by the company.

The ultimatum ended Tuesday dawn.

With this, PAL is now set to file charges against the pilots for violating their contract with the company.

PAL said it will start processing the case to be filed against those who resigned without proper notice, leaving several flights of the airline cancelled and hundreds of passengers stranded. (Sunnex)