The Federal Aviation Administration says helicopters will be permanently banned from flying near Washington, D.C.’s airport on the route where an airliner and an Army helicopter collided in midair.

When Congress pushed ahead last year with adding 10 new daily flights to the Reagan National Airport in Washington, D.C., the Federal Aviation Administration had data showing an unnerving number of near misses in the already-crowded skies — something lawmakers apparently did not know.