From my favourite pilot’s blog ((Well worth bookmarking – only one or two posts a week, but always with a nice photograph.)), Flight Level 390: See what happens when you try to manoeuvre 75 tons of A320 ((“Fi-Fi” to her friends.)) on a sheet of ice:

After we loaded 150 passengers and bags, the tug crew pushed our aircraft shaped iceberg back while the co-pilot started number one engine. Ground control cleared us to taxi to the ice pad. As I advanced number one throttle, Fi-Fi slowly slid on the icy ramp in the direction of the thrust vector. Ooops! Not good… We are forced to start number two for symmetrical thrust. Slowly, very slowly, I taxied to the Ice Man’s ramp which was full of airliners being sprayed with hot de-icing fluid. Ice Man, actually a woman, asked us to proceed to spot #9 and configure the aircraft for de-icing fluid. Then, in a last second change of plans, she asked us if we could proceed to spot #7. I turned the nose wheel left but Fi-Fi kept going straight.
“Tell her we can’t accept spot #7.”

No kidding.