Family members of some of the 67 people killed in January’s midair collision in Washington listened to the US Army and Federal Aviation Administration take fiery questions from lawmakers for the first time Thursday at a Senate subcommittee hearing on the preliminary findings of the accident.

If investigators were able to quickly find alarming data about the number of close calls in the years before the midair collision over the nation's capital that killed 67 people in January, then aviation safety regulators should have seen the problem,

NTSB is investigating a “potential for equipment malfunction” with ADS-B Out transponders, agency Chair Jennifer Homendy said Thursday.

During the hearing, the head of the National Transportation Safety Board and members of Congress again questioned how the FAA hadn’t noticed an alarming number of close calls near Ronald Reagan National Airport and addressed the problem before the January collision between an Army helicopter and a jetliner.

The head of the Federal Aviation Administration has told Congress that the agency must do more to ensure flying remains safe after a midair collision over Washington, D