The U.S. federal agency responsible for investigating transportation accidents is calling for immediate changes at Reagan National Airport near Washington, D.C. following a deadly mid-air collision involving an American Airlines flight and a U.S. Army helicopter earlier this year.

The National Transportation Safety Board issued an "urgent recommendation report" Tuesday, pressing for the Federal Aviation Administration to prohibit helicopters from flying on "Route 4 between Hains Point and the Wilson Bridge when runways 15 and 33 are being used for departures and arrivals."

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The NTSB also urged the FAA to designate an alternative helicopter route that can be used when those runways are in use.

The recommended changes are in response to the crash that occurred on Jan. 29, when an American Airlines regional jet traveling from Wichita, Kansas, was preparing to land at Reagan National Airport. The jet collided with a Black Hawk helicopter conducting a training flight.

Both aircraft plunged into the Potomac River, killing all 67 people aboard.

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NTSB chair Jennifer Homendy has cautioned that the radio altitudes captured by flight recorders and the altitudes the flight crews saw from their main instruments may have conflicted. Officials said the collision likely occurred just under 300 feet — well above the helicopters 200-foot limit in that area.

The NTSB has not yet issued a final report about the crash, maintaining that all of its investigative findings are preliminary. Homendy reiterated to reporters Tuesday that it will take time to completely analyze all of the data and variables involved in the incident.