Sister Bertrille could be relied upon to solve any problem that came her way by her ability to catch a passing breeze and fly. This was generally attributed to her weighing under , high winds at the Convent high on the ocean bluffs, and the large, heavily starched cornette that was the headpiece for her habit. (The cornette was based on one worn until the middle 1960s by the Daughters of Charity, although Sister Bertrille was never said to belong to that order. Indeed, the order which included the Convento San Tanco was never actually specified in the series.) Her flying talents caused as many problems as they solved. She explains her ability to fly by stating, "When lift plus thrust is greater than load plus drag, anything can fly." In one episode, she tries to gain weight so she could stay grounded, but the attempt fails. Additionally, in the first-season episode "Young Man with a Cornette," she specifically tells a young boy who intended to use her cornette to fly that there were many factors other than her weight (which was distributed differently from that of the boy) that made her flying possible. She was unable to take off only when heavy rains or storms caused her starched cornette to lose its shape, when she had to wear something that would keep her grounded at all times, or, on one occasion in the episode titled "The Flying Dodo", when an inner ear infection caused her to lose her balance.