December 6, 2006 (by Lieven Dewitte) -
A USAF F-16 of the 35th Fighter Wing based at Misawa AB, Japan, accidentally dropped a concrete practice bomb on a runway shared by civilian and military flights.

BDU-33 training bombs on a Triple Ejector Rack (TER)
The jet came back from a night training and landed at about 19.25h at Misawa AB. Upon the after-flight check it was discovered that one BDU-33 practice bomb was missing from the jet. After a brief search, the non-explosive ordnance was retrieved from the runway.
The BDU-33 is used in training to simulate actual bombs. These 650 mm long, 11kg (25 pound) practice bombs accurately simulate large and heavier live bombs by their tail fin guidance system.
Mid-November, the same kind of practice bomb fell off a Misawa F-16 during a routine training mission.
Misawa AB is on the northeast end of Honshu Island, approximately 325 miles north of Tokyo, adjacent to Misawa City in the Aomori Prefecture. F-16s operate at all altitudes within a 200 NM radius of the base. Approximately 50 sorties are launched daily.
For most training missions, F-16s fly to the Charlie MOAs off the west coast. F-16s also frequently fly between the base and Ripsaw Range, 10 NM to the north. Misawa's simulated flameout (SFO) practice pattern extends to 10,000' over the airfield.