Underwater robots have spotted part of the cabin, bodies and engines of an Air France plane on the Atlantic Ocean floor _ nearly two years after it crashed in 2009. Here are some key moments in the unprecedented and protracted search for wreckage:

June 1, 2009: Crash of Air France flight 447

June 6: First bodies and debris recovered, 680 miles northeast of Fernando de Noronha islands off Brazil's northeast coast.

June 10: First month-long undersea search begins to listen for signals from black box flight recorders.

June 27: Search for bodies called off.

July 1: Emergency beacons on aircraft's black boxes believed to stop transmitting.

July 10: First search for black boxes ends unsuccessfully.

July 27-August 17: Second undersea search, unsuccessful.

April-May, 2010: Third undersea search, unsuccessful.

March 25, 2011: Fourth undersea search effort begins.

April 4, 2011: Robots spot large piece of plane including bodies, engines, cabin.