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’s preliminary report on the Jan. 29 crash that killed 67 people said current helicopter routes allowed around the airport are an ‘intolerable risk to aviation safety.’