On *** typical morning you'd see planes right over my shoulder here making their way into Reagan National Airport. That's the same flight path that that plane and helicopter crashed last night on. Now, many have been wondering how did all of this happen? Why did it happen? And we at the National Investigative Unit have obtained audio recordings from air traffic control that sort of help paint the story. This is the terrifying moment the American Airlines flight collided with an Army Black Hawk helicopter at 8:48 Wednesday night. After the horrific crash, multiple local and federal agencies sending rescue units. The Army helicopter was on *** training flight near the river, an area that often has heavy military and law. Helicopter traffic at all hours. We're learning more about the path of Flight 5342 as well. *** few minutes before landing, air traffic controllers asked the jet if it could land on *** shorter runway, and the pilot says yes. Controllers then cleared the plane to land. *** short time later, audio we obtained pinpoints the moment inside the air traffic control tower as they witnessed the collision. Audible gasps heard in the background and seconds later. The national investigative The Unit also tracked what appears to be the adjusted final approach. You can see it brought the plane east of the main runways and over the river. The last tracking point we found, the plane was at an altitude less than 300 ft, going about 128 miles an hour. Now just beyond those smoke stacks over there is sort of *** staging area for search and rescue. We were down there all night long until we had to get pushed back to where we are right now, but when we were down there, we did see pieces of that plane being taken out of the water and also unfortunately the bodies of some of those who lost their lives. Reporting in Washington DC, I'm national investigative correspondent John Cardinelli.