After announcing a major workforce reduction at the beginning of the year, Air Wisconsin is planning another round of layoffs affecting more than 100 people.

In a layoff notice filed with the state, the regional airline based in the Fox Valley said the workforce reduction comes in response to uncertainty in the economy and the airline industry.

The airline says the layoffs will affect workers at airports in both Milwaukee and Appleton.

In the notice, Tina Vos, vice president of human resources for Air Wisconsin Airlines, said the layoffs are expected to be temporary for unionized employees and permanent for management and salaried employees.

“The duration of the reduction is unknown and will be dependent on future opportunities, as they may arise,” Vos wrote. “The resulting reduction will affect approximately 128 salaried/ management.”

The layoffs will be effective in June for non-union employees, but they could happen sooner for union workers, the airline said.

In January, Air Wisconsin announced that more than 500 people would be affected by a mix of temporary and permanent layoffs. According to that layoff notice, that round affected 219 management employees and 294 union workers.

Those layoffs came after the company said it was terminating an agreement with American Airlines that allowed Air Wisconsin to take flights for the major airline. Air Wisconsin had said the move would allow it to focus on federally subsidized “Essential Air Service” routes that connect to rural and underserved communities.

In the most recent layoff notice, the company indicated that it’s struggled to find new opportunities.

“Although we have been diligently pursuing alternative flying opportunities, recent uncertainty in the general economy and the airline industry has caused us to re-evaluate our strategy,” Vos wrote.