Earlier, Ferrari technical boss Aldo Costa played down suggestions the team's F-duct solution is dangerous.
Unlike McLaren's system which is believed to be activated by the drivers' knees, it became clear in Barcelona that Alonso and his teammate Felipe Massa are triggering the airflow on the straights with their left hand.
Often at the same time, the drivers are then using their right hand to make adjustments to the brake balance.
But Alonso insisted after qualifying: "I always have my hands on the steering wheel."
Indeed, onboard video shows that the Spaniard has a black pad sewn onto the knuckles of his left glove that allows Alonso to block the airflow while keeping his thumb in place on the steering wheel.
"There is no problem," he told Germany's Motorsport-Magazin.com.