Imperial Airlines will lay off up to 20% of its staff.

Citing drops of more than 30% in both passengers and revenue, the Carlsbad-based carrier said it will lay off between 15% and 20% of its 210-employee work force by the end of the month as part of a restructuring to become a discount commuter airline. The layoffs likely will come from the firm’s 56 pilots and nine flight attendants, President James Harmon said.