The F.A.A. has since been training on-call specialists to be snappier about administering alcohol and drug tests after a serious incident, an official said.

Air traffic control managers told the National Transportation Safety Board that F.A.A. leaders rebuffed efforts over the years to address hazardous conditions that played a role…

The F.A.A. has since been training on-call specialists to be snappier about administering alcohol and drug tests after a serious incident, an official said.