The Federal Aviation Administration failed to heed numerous appeals in recent years to mitigate risks at Ronald Reagan National Airport, forcing pilots and air traffic controllers to make the best of hazardous options, according to testimony at a hearing Thursday on the January midair collision over the Potomac River.

Officials assigned to air traffic control facilities in the area around Washington, D.C., said that senior F.A.A. managers squelched or disregarded formal efforts to reduce the rate of departures and arrivals at the airport, to make changes to a route that put helicopters in proximity to planes landing on one of its runways, and to get support staff assigned to the airport tower to ease the workload of controllers trying to manage a frequently chaotic airspace.

The testimony came in the second of three days of hearings before the National Transportation Safety Board, the agency that investigates aviation accidents. The sometimes contentious hearings aimed to probe the circumstances leading to the collision between an Army Black Hawk helicopter and a commercial jet, killing 67 people, on Jan. 29 — the worst airplane crash in nearly a quarter of a century in the United States. A report on the agency’s findings of the causes is not expected to be released until early next year.

It cannot be known if the changes urged by employees with the F.A.A., if put into action, would have prevented the collision, but the unheeded warnings indicate that there were multiple opportunities for the agency to address conditions that may have contributed to the crash.

“If a facility is coming to you with this type of information — I didn’t do it lightly — and it needs to be addressed, and we didn’t address it,” said Bryan Lehman, the F.A.A. official in charge of the Potomac TRACON, which directs traffic headed to or from the Washington, D.C., area.

Mr. Lehman told the board that in 2023, he wrote a formal memo asking the F.A.A. to reduce the rate of arrivals at National Airport, having noticed that at peak times, controllers were struggling to keep up with traffic that frequently exceeded capacity.