the trunk of a buoyant tree, usually a Bloodoak, and the tree was lit on fire. Then, the victim went soaring up, launched like a rocket, from the sky ship. Even later, in the Third Age of Flight sky-firing was used as a punishment for thieves on sky-taverns.
Sky-Firing almost always resulted in death, but it was possible to deliberately execute it in a way that allowed the victim to survive, using it as means of travel, even; however, this has only been seen once in the series.
Having arrived at Riverrise, Twig and Cowlquape were informed that Sanctaphrax's anchor chain needed to be severed in order to let the Mother Storm pass. Lacking any other method of getting to Undertown in time, Twig and Cowlquape were sky-fired back to the edge cliff, landing in the stone gardens.
Many years later, when Twig was returned to Riverrise by the Caterbird and imprisoned there by Golderayce, he considered Sky-Firing as an escape method. However, he did not attempt it, as he would not have survived the trip as an old man, and also because Maugin, who had calculated the angle of flight on the previous journey, was no longer present to help.