AT-AT weapons are rarely quick enough to score a direct hit on a fastmoving snowspeeder. They are more likely to wing a craft, causing a forced landing.
If you have a piloted AT-AT present at a site, target opponent’s non-creature vehicle present at same or adjacent exterior site. Draw destiny. If AT-AT has a vehicle weapon, add 1 to destiny draw. Target ‘crashes’ if total destiny > 3.