The relationship between the National Transportation Safety Board, the government entity that investigates civilian airplane accidents, and the Federal Aviation Administration, the agency responsible for aviation safety, can frequently be contentious, especially after a major national tragedy.

Last week, a rift between those two main regulators of aviation safety spilled out into public view.

Frustrations — and sometimes tempers — flared in uncommonly raw fashion during the board’s marathon of investigative hearings into the deadly midair crash between a military helicopter and a commercial jet near Ronald Reagan National Airport in January. Board members grilled witnesses, including air traffic controllers and F.A.A. managers, over three days and 30 hours of public testimony.

Jennifer Homendy, the N.T.S.B. chair, led other board members in accusing the F.A.A. of knowingly stymieing efforts to improve safety at Reagan National Airport and stonewalling parts of the board’s investigation into the crash. And Ms. Homendy directly accused the agency of fostering a culture among the air traffic control operation that discouraged employees from raising legitimate safety concerns, including by wielding the threat of retaliation.

“There is and always has been a healthy tension between the two agencies,” said Jeff Guzzetti, a former accident investigator for the F.A.A. and the N.T.S.B. And while the level of public outrage on display during board hearings depends largely on the proclivities of its members, he added, “in this particular case, it’s a shift.”

Ms. Homendy and the other board members were careful not to direct their ire toward Sean Duffy, the transportation secretary, or Bryan Bedford, the F.A.A. administrator. Still, the very public airing of grievances raised questions about the working relationship between the two agencies at a critical juncture.