Rescue workers walk in a field before an official ceremony near the crash site of the Germanwings Airbus A320 in Seyne-les-Alpes on March 25, 2015. Investigators combed through the pulverised wreckage of the German airliner and examined its badly damaged black box for clues as to what caused the mysterious crash that killed all 150 aboard. AFP PHOTO / POOL / CHRISTOPHE ENA