Duffy slams Defense Department over recent DCA incident: 'No more helicopter rides for VIPs' / Over 40 percent of DCA flights were delayed or canceled last month / 3D analysis shows how helicopter pilots could have mixed up jets in DCA crash / Altimeter in Black Hawk helicopter may have malfunctioned before DCA mid-air collision / NPR's Adrian Ma remembers girlfriend, Kiah Duggins, who died in DCA plane collision / Flight recorders recovered in DCA crash / Watch live: NTSB gives update on DCA crash probe / DCA crash: Timeline of Black Hawk, plane collision