Why Airlines Don’t Allow More than 100ml Liquid in Cabin? For air travellers worldwide, understanding the reasoning behind the 100 ml liquid restriction can transform frustration into appreciation for these necessary security measures that have helped maintain safe skies. The 100ml liquid restriction for air travel was introduced in 2006 after authorities uncovered a terrorist plot involving liquid explosives. Security experts determined that containers of 100ml or less cannot hold sufficient quantities of liquid explosives to cause catastrophic damage to an aircraft. Even if multiple 100ml containers were combined, the total volume would remain below the threshold needed for a major explosive event.