A jet with 60 passengers and four crew members collided with an Army helicopter Wednesday while approaching the Ronald Reagan National Airport near Washington. The aircraft plummeted into the Potomac River and multiple people were killed. The crash occurred in some of the most tightly controlled and monitored airspace in the world, just over 3 miles (5 kilometers) south of the White House and the US Capitol. Here are some things to know about the collision: The crash The midair crash happened around 9 pm when a regional jet at the end of a flight from Wichita, Kansas, collided with a military helicopter on a training exercise, according to the Federal Aviation Administration. A few minutes before the jet was to land, air traffic controllers asked American Airlines Flight 5342 if it could land on a shorter runway and the pilots agreed. Controllers cleared the jet to land and flight tracking sites showed the plane adjust its approach to the new runway. Less than 30 seconds before t