WASHINGTON — The Federal Aviation Administration is bringing thousands of furloughed inspectors and other employees back to work as the partial government shutdown drags on, the agency said Tuesday.

The F.A.A.’s announcement came after unions representing aviation safety inspectors and air traffic controllers raised concerns that the lengthy shutdown was eroding the safety of the United States’ air travel system.

It is one of the largest changes made by a government agency to address the need to maintain an essential service since the shutdown began last month. The Internal Revenue Service is planning to bring back tens of thousands of furloughed workers for tax season, and the Food and Drug Administration has said it is bringing hundreds of workers back to step up food safety inspections.

Under its revised shutdown plan, the F.A.A. will have 3,113 employees in its aviation safety organization who are considered essential to protect life and safety, and those employees will work without pay. Under its original shutdown plan, only 216 aviation safety positions were considered essential for life and safety.