Three senior Democratic lawmakers on Tuesday urged the Federal Aviation Administration to address significant safety issues at Reagan Washington National Airport and maintain reduced air traffic after a series of troubling incidents.

The Federal Aviation Administration says analysis in the wake of January’s crash between an Army helicopter and a passenger jet landing at Ronald Reagan Washington National Airport and has identified other airports where the risks of similar collisions are too high.

The Federal Aviation Administration (FAA) has implemented stricter controls on helicopter operations around Las Vegas’ Harry Reid International Airport following a review sparked by January’s fatal mid-air collision near Washington, D.C.