FAA administrator Michael Huerta said the agency has instituted a hiring freeze and will have “no choice” but to start employee furloughs in April.

Citing the US government’s budget sequestration that started last week, Huerta said FAA this week is sending furlough notices to most of its 47,000 employees. Most agency workers will be furloughed one day every two weeks starting next month, he said.

Speaking Wednesday at the Aviation Forecast and Policy Summit in Washington DC, Huerta rejected suggestions that FAA could avoid furloughs and air traffic control service reductions. The sequestration law “limits our ability to prioritize [cuts] across the full spectrum of activities” and mandates immediate cuts “as opposed to [implementing budget reductions with] a longer lead time,” he said.

FAA’s budget has to be reduced by more than $620 million between now and the Sept. 30 end of the US government’s fiscal year.

Huerta said FAA’s sequestration strategy is to have “minimal impact to the maximum number of travelers” by reducing services and closing facilities at the least busy airports first. But the severity of the cuts will inevitably mean flight delays at large US airports, he explained.

“These are all terrible choices,” he said. “In order to maintain a safe system, we may need to take a penalty in terms of efficiency.”