25-years-ago on Monday, April 4, a small plane was making its approach into Philadelphia International Airport when the pilot reported trouble with the landing gear. A helicopter pilot tried to take a closer look at the landing gear, and the plane and the helicopter collided.
http://philadelphia.cbslocal.com/2016/04/03/a-community-remembers-fatal-lower-merion-plane-crash-25-years-later/