A supply channel for a means of transportation is provided. The supply channel comprises a fluid line, an inflatable projection element having an opening and a pressure sensor which is configured for determining a pressure difference between an internal pressure in the projection element and an ambient pressure. The inflatable projection element is connected to the fluid line via the opening. The projection element is configured for being transferred from a compressed state to an inflated state by filling it with fluid from the fluid line. The projection element provides a predetermined projection surface in the inflated state.