Chicago Tribune
“A little bit of ice will take an airplane out of the sky,” Boyd said, so airlines are extra cautious when they run out of fluid. An airline can only store so much glycol at the airport, and the combination of several days of snowy weather and a
Southwest Airlines Just Made Passengers Very Angry (and This Isn’t the First Time It’s Happened)
Southwest Airlines cancels hundreds of flights after running low on de-icing fluidFox News
Southwest Airlines expecting normal operations at Midway Monday after running out of de-icer SundayWLS-TV

Source: TRAVEL