A computer-implemented method of controlling a gimbal stabilisation system of an aircraft in an antenna test system for testing an antenna under test, AUT, the gimbal stabilisation system comprising a control assembly rotatably coupled to a gimbal assembly comprising a payload, the payload comprising a first section including a communication sensor interface for use in testing the AUT and a second section, the payload rotatably coupled to the gimbal assembly, the control assembly comprising a controller, the method, performed by the controller, further comprising: receiving an in-flight position of the aircraft during testing of the AUT; characterised by the method further comprising: receiving a position of the AUT in relation to the aircraft; and controlling the gimbal assembly by: calculating a pointing direction and alignment of the first section of the payload relative to the AUT based on the received position of the aircraft and the received position of the AUT; and maintaining pointing and alignment of the first section of the payload towards the AUT based on the calculated pointing direction and alignment of the first section of the payload, further comprising: controlling the pointing and the alignment of the first section of the payload about at least three axes of rotation, wherein one axis of rotation of said at least three axes of rotation is configured to control said alignment of the first section of the payload, wherein said alignment of the first section of the payload comprises a polarisation alignment of the communication sensor interface. receiving a position of the AUT in relation to the aircraft; and controlling the gimbal assembly by: calculating a pointing direction and alignment of the first section of the payload relative to the AUT based on the received position of the aircraft and the received position of the AUT; and maintaining pointing and alignment of the first section of the payload towards the AUT based on the calculated pointing direction and alignment of the first section of the payload, further comprising: controlling the pointing and the alignment of the first section of the payload about at least three axes of rotation, wherein one axis of rotation of said at least three axes of rotation is configured to control said alignment of the first section of the payload, wherein said alignment of the first section of the payload comprises a polarisation alignment of the communication sensor interface. calculating a pointing direction and alignment of the first section of the payload relative to the AUT based on the received position of the aircraft and the received position of the AUT; and maintaining pointing and alignment of the first section of the payload towards the AUT based on the calculated pointing direction and alignment of the first section of the payload, further comprising: controlling the pointing and the alignment of the first section of the payload about at least three axes of rotation, wherein one axis of rotation of said at least three axes of rotation is configured to control said alignment of the first section of the payload, wherein said alignment of the first section of the payload comprises a polarisation alignment of the communication sensor interface.