Summarize this content to 2000 words in 6 paragraphs American Airlines Flight 5342, a regional jet en route from Wichita, Kan., was zooming down and about to land at Ronald Reagan National Airport in Washington on Wednesday night, when it made a last-minute turn upward.Investigators with the National Transportation Safety Board appeared unsure if that meant that the pilots were alerted to something wrong in the plane’s final descent. But the sudden change in trajectory was not enough to avoid colliding with a military helicopter that was flying higher than it was supposed to be.“I can tell you at one point very close to the impact, there was a slight change in pitch, an increase in pitch,” said Todd Inman, a member of the safety board.In a briefing Saturday, members of the board provided new information and more detail than previously revealed of the moments leading up to the midair crash that proved to be the deadliest aviation accident in the United States in nearly a quarter of a century.The regional jet and the Army Black Hawk helicopter collided between 300 feet and 350 feet above the ground over the Potomac River, according to the investigators who recovered information from the flight data recorders.That places the helicopter more than 100 feet above the height that it was authorized to fly in its particular route near Reagan. Helicopters must fly at designated heights and remain in specific paths to avoid commercial airplanes coming in and out of the busy airport.On the route that the helicopter was approved to fly Wednesday, called Route 4, it was not authorized to fly higher than 200 feet above ground.The New York Times earlier reported that the helicopter was flying higher than authorized, putting it within the path of the American Airlines regional jet, killing all passengers aboard both aircraft.One aspect that is perplexing investigators: The radar scope that the air traffic controller was using Wednesday night appeared to show the Black Hawk at only about 200 feet off the ground at the time of the crash. However, investigators cautioned that this was based on preliminary data that still need to be verified.Investigators say they do not know why the air traffic controller would have information that was not accurate about the helicopter’s height at the point of collision.“That’s what our job is — is to figure that out,” Mr. Inman said. “That’s what we’re doing.”Investigators also provided a detailed accounting of the air traffic communications with both aircraft on Wednesday night. One controller handled the traffic duties with both the passenger jet and the helicopter after a second controller was allowed to leave the shift earlier than usual, The Times previously reported.About 8:15 p.m. the American Airlines plane left 37,000 feet to begin its initial descent. About 25 minutes later, controllers cleared the pilots to land.About 8:43 p.m. the controller asked the plane’s crew if they could switch their landing from Runway 1 to Runway 33. (Runway 33 is shorter than Runway 1, requiring intense focus from pilots landing their planes, the Times previously reported.)“After a brief discussion with the crew, they agreed to switch to runway 33,” said Brice Banning, a member of the N.T.S.B.Two minutes after that, the jet’s autopilot was disengaged.Activity ramped up 8:46 p.m. The controller informed the helicopter pilots that there was a passenger jet circling to land onto Runway 33. Then the controller cleared another jet on Runway 1 to take off.In the next minute, when the passenger jet was about 500 feet off the ground, the controller asked the helicopter crew if the commercial jet was in sight and then directed the helicopter to pass behind it.A second later, the plane received an automated advisory saying: “Traffic. Traffic.”At 8:47:58 the plane crew could be heard uttering something and the flight data recorder showed the plane began to increase its pitch.Immediately after, the sound of impact was heard by the air traffic controller.
