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

The NTSB says the current helicopter routes around the busy airport "pose an intolerable risk to aviation safety" in the wake of January's collision that killed 67 people.

Six weeks after 67 people perished in a D.C. midair collision, the NTSB’s preliminary report exposes a history of near misses between commercial jets and helicopters at the airport.