A method of using an aerial device capable of controlled flight, the device comprising: a lift generator for providing lift to the aerial device; and a suspension device for suspending the aerial device from an object, wherein the method comprises: controlling the lift generator so as to controllably fly the aerial device relative to a supporting structure; and using the suspension device to suspend the aerial device from the supporting structure, characterized in that the suspension device is arranged to retractably deploy an elongate flexible member by a controllable length, for suspending the aerial device from the supporting structure using the elongate flexible member, the method further comprising: detaching, by the aerial device, the aerial device from the elongate flexible member, thereby releasing the aerial device from its suspension from the supporting structure, wherein detaching the aerial device comprises deploying the full length of the elongate flexible member such that the aerial device detaches from the elongate flexible member, or, wherein the device is arranged to sever the elongate flexible member, and detaching the aerial device comprises severing the elongate flexible member. a lift generator for providing lift to the aerial device; and a suspension device for suspending the aerial device from an object, wherein the method comprises: controlling the lift generator so as to controllably fly the aerial device relative to a supporting structure; and using the suspension device to suspend the aerial device from the supporting structure, characterized in that the suspension device is arranged to retractably deploy an elongate flexible member by a controllable length, for suspending the aerial device from the supporting structure using the elongate flexible member, the method further comprising: detaching, by the aerial device, the aerial device from the elongate flexible member, thereby releasing the aerial device from its suspension from the supporting structure, wherein detaching the aerial device comprises deploying the full length of the elongate flexible member such that the aerial device detaches from the elongate flexible member, or, wherein the device is arranged to sever the elongate flexible member, and detaching the aerial device comprises severing the elongate flexible member. controlling the lift generator so as to controllably fly the aerial device relative to a supporting structure; and using the suspension device to suspend the aerial device from the supporting structure, characterized in that the suspension device is arranged to retractably deploy an elongate flexible member by a controllable length, for suspending the aerial device from the supporting structure using the elongate flexible member, the method further comprising: detaching, by the aerial device, the aerial device from the elongate flexible member, thereby releasing the aerial device from its suspension from the supporting structure, wherein detaching the aerial device comprises deploying the full length of the elongate flexible member such that the aerial device detaches from the elongate flexible member, or, wherein the device is arranged to sever the elongate flexible member, and detaching the aerial device comprises severing the elongate flexible member.