An aerofoil comprising an air-redirection formation for a tip portion of the aerofoil, wherein the air-redirection formation includes: a first portion, which includes a first surface which forms a continuation of the aerodynamic lifting surface of the aerofoil, the aerodynamic lifting surface of the aerofoil defining a horizontal plane; and a second portion connected to the first portion by a connection structure, the second portion including a second surface spaced from the first portion via the connection structure, and the second portion being in the horizontal plane of the aerofoil or below the horizontal plane of the aerofoil; wherein, in use in nominal flight conditions, the first surface is substantially horizontal and is for directing vortices away from the aerofoil and towards the second surface, and the second surface is substantially horizontal and is positioned to interact with the directed vortices, and wherein the air-direction formation is connected to the aerofoil; and the connection structure comprises at least a first connection element and a second connection element, the first connection element and second connection element being joined by a third connection element, the first connection element being connected to the first portion of the air-redirection formation, wherein the first connection element projects rearwardly and downwardly from the first portion; and the second connection element being connected to the second portion of the air-redirection formation, wherein the second connection element projects forwardly and downwardly from the second portion. a first portion, which includes a first surface which forms a continuation of the aerodynamic lifting surface of the aerofoil, the aerodynamic lifting surface of the aerofoil defining a horizontal plane; and a second portion connected to the first portion by a connection structure, the second portion including a second surface spaced from the first portion via the connection structure, and the second portion being in the horizontal plane of the aerofoil or below the horizontal plane of the aerofoil; wherein, in use in nominal flight conditions, the first surface is substantially horizontal and is for directing vortices away from the aerofoil and towards the second surface, and the second surface is substantially horizontal and is positioned to interact with the directed vortices, and wherein the air-direction formation is connected to the aerofoil; and the connection structure comprises at least a first connection element and a second connection element, the first connection element and second connection element being joined by a third connection element, the first connection element being connected to the first portion of the air-redirection formation, wherein the first connection element projects rearwardly and downwardly from the first portion; and the second connection element being connected to the second portion of the air-redirection formation, wherein the second connection element projects forwardly and downwardly from the second portion. the first connection element being connected to the first portion of the air-redirection formation, wherein the first connection element projects rearwardly and downwardly from the first portion; and the second connection element being connected to the second portion of the air-redirection formation, wherein the second connection element projects forwardly and downwardly from the second portion.