Bags of food fall from the sky as a plain unloads its humanitarian cargo in midair. This is an airdrop -- one of the most iconic images of humanitarian assistance, even though they don't actually happen very often. WFP started airdrops of food in South Sudan in March 2014, because of insecurity and other barriers to humanitarian access that made it otherwise impossible to reach many remote conflict-affected communities. In three days of airdrops, the plane in this photo delivered cereals and pulses to feed about 25,000 people for 15 days in Ganyiel, Unity State, one of the first locations to be reached by the airdrop operation.


But what happened before the hold opened and food bags plunged to the ground? And what happened after this shot? This series of photos will explain...