Air traffic control employees at Ronald Reagan National Airport (DCA) are often forced to "make it work" with limited resources, Federal Aviation Administration officials said during the second day of the National Transportation Safety Board's hearing into afatal January crash. Sixty-seven people died after an Army Black Hawk helicopter collided with an American Airlines regional jet on January 29 over the Potomac River close to Washington. It was thedeadliest U.S. aviation accidentin decades. The NTSB launched a probe into the tragedy, which includes a three-day investigative hearing taking place this week. Here are some major takeaways. Preliminary investigative results released shortly after the accident showed the FAA was aware of ongoing risks at the airport, particularly with military aircraft, but did not take action before the crash, the NTSB alleged. Other issues with DCA included airspace congestion and a shortage of air traffic controllers. Following the tragedy, the FAA restricted the use of military helicopters along Route 1, a helicopter route on the Potomac River that passed in front of DCA's runway 33. Wednesday and Thursday's portions of the hearing partly focused on the roles the Army and FAA played on the night of the crash, with NTSB Chairwoman Jennifer Homendy telling FAA officials the agency did not act on warnings from air traffic control staff who had previously suggested flight path changes to avoid collision threats. "Every sign was there that there was a safety risk, and the tower was telling you," said the chairwoman. In a statementposted to X, Senate Commerce Committee Chair Maria Cantwell, D-Washington, who has been a leader in the investigation into the incident, said: "The NTSB hearing revealed the conflicts on the DCA helicopter routes were so clear that an air traffic control working group suggested changing them. "What caused the FAA's oversight to be so flawed that they couldn't fix this problem before this tragedy occurred?" Is flying still safe?:Yes. Here's what travelers should know. NTSB investigator Brian Soper asked air traffic control officials whether a "make it work mentality has been normalized at DCA airport." National Airport Operations Manager Clark Allen said he believed it had. "There's limited real estate for the airport and where to put aircraft, and that can back up very easily," Allen testified. "So, being a high-volume, high-complexity airport, with not a lot of real estate, you have to keep things moving in order to provide a safe and efficient service." Bryan Lehman, an FAA front-line manager, said his tower is currently dealing with many of the issues DCA has and is performing "non-standard air traffic maneuvers" on a daily basis. "We take pride in it," said Lehman, adding, "But I will say that at a certain point, it's too much." Investigators also pressed officials on staffing turnover. Allen said Wednesday that the DCA control tower has had approximately 10 air traffic wardens since early 2013. "Air traffic managers are responsible for considering any sort of changes to routes, any sort of changes, amendments, evaluation of routes annually," Homendy responded. "You've had 10 air traffic managers in a pretty small amount of time. You've had five in the past five years, three in the past two years. How are they supposed to know to do that if you keep switching air traffic managers?" Many of the victims of the plane crash were children and their parents returning from a figure skating competition in Wichita, Kansas. Speaking to ABC affiliateWJLA, Aisha Duggins, whose sister Kiah Duggins died in the crash, said the hearing "brings me hope that we're having these conversations," even though some of the results of the investigation are "deeply unsurprising." Contributing: Nathan Diller, USA TODAY Michelle Del Rey is a trending news reporter at USA TODAY. Contact her at mdelrey@usatoday.com. This article originally appeared on USA TODAY:FAA, Army grilled on Potomac plane crash in investigative hearing