The SW-4 ion cannon was a notoriously delicate weapon system, and its internal crystal matrices invariably vibrated out of alignment during flight or combat. Rebel mechanics came to dislike the SW-4 due to the time they were forced to put in to maintain the cannons. At the Battle of Yavin, only two of the Alliance's Y-wing fighters had functional ion cannons.
The BTL-S3 Y-wing variant had space for a weapons systems officer, who manually operated the SW-4 turret when necessary. Single-pilot variants had their cannons locked forwards for optimum covering fire, though some pilots chose to lock it facing aft to counter pursuers.