Gas is prone to be entrapped in the casting resulting from the reaction of molten metal with mold coating material and resin hardened sand cores during filling in gravity diecasting of aluminum alloys with complex shape. Tilted pouring is known to be one of the method to eliminate the gas defect, in which tilting speed and angle are important as operation variables. Transparent water model was employed to observe the gas entrapment and liberation during pouring of complex shaped casting in this study. As a result, slow tilting combined with movable pouring ladle is recommended to evolute gas effectively in gravity diecasting.