When aircraft volume goes down, a supervisor can make the decision to combine two controller positions into one position. This happens routinely, and on Wednesday at Reagan Airport, it happened 40 minutes earlier than it normally does because the supervisor determined that the traffic was low enough to combine, according to a source with direct knowledge.

This position handles local arrivals into Reagan and helicopter traffic when it’s combined.

Reagan is not understaffed, the source added.

The air traffic controllers’ union said in a statement that it’s working with all federal agencies and “stands with the highly trained, highly skilled” workforce that “keeps the United States as the gold standard for aviation safety.”