Training of new air traffic controllers, rulemaking activities and long-term NextGen progress are among the key FAA efforts that will cease under a government shutdown, the U.S. Transportation Department’s (DOT) funding-lapse contingency plan shows.

The FAA stands to lose about one-third of its 46,000 employees under a shutdown that at press time was scheduled to start today. Of the FAA’s 30,500 remaining employees, 24,200 will be in the Air Traffic Organization.

However, the DOT document notes that a shutdown would suspend “development of new air traffic control specialists not certified to work a position.”

Much of the FAA will continue to operate in a business-as-usual mode during the shutdown, the DOT’s plan shows. Besides air traffic control (ATC) operations and facility upkeep, other services that will continue include airport and flight standards-related field inspections, commercial space launch oversight, aircrew and ATC personnel medical certifications, and accident investigation.

Long-term NextGen efforts will slow a bit, the DOT says. The agency includes “developmentoperational testing, and evaluation of NextGen technologies” and “development of NextGen safety standards” on the list of suspended activities.The DOT notes that En Route Automation Modernization deployment will continue.

While non-safety-related critical rulemaking will halt, the FAA’s Aviation Safety (AVS) workforce—limited initially to “safety-critical staff whose job is to perform urgent continued operationalactivity to protect life and property”—will steadily rebound if the shutdown drags on. The FAA will bring back about 2,800 AVS employees over the next several weeks“tobetter manage safety risk,” the DOT explains.

Employees would be called back based on “the percentage of continued operational safety work.”

Among other functions that will cease are air traffic performance analysis, dispute resolution, capital planning for facilities and equipment, and budgeting functions not tied to multi-year appropriations or contract authority.

The FAA—by far the largest agency within the 55,500-employee DOT—would also be among the hardest-hit by any government shutdown.

Neither the Federal Highway Administration nor the Federal Motor Carrier Safety Administration—the next-largest DOT agencies by staff size—will lose any of their employees.However, nearly the entire 400-person Inspector General’s staff and the 530-member Federal Transit Administration, as well as more than half of the 900-strong Federal Railroad Administration would be furloughed until Congress pushes through a full or partial fiscal 2014 spending bill for the DOT.