The subject matter disclosed herein includes, inter alia, a method and system which enables to determine the steering-angle between the longitudinal axis of a tractor and the longitudinal axis of an aircraft which is being led by the tractor (referred to herein as “steering-angle” in short). While an aircraft is being led, the steering-angle can be repeatedly calculated and compared to a threshold value defining a mechanical steering limit. In case the comparison complies with one or more predefined conditions (e.g. the steering-angle is equal or smaller the threshold value) a warning can be generated indicating to an operator that the steering-angle has reached (or is about to reach) its limit and should be adjusted accordingly.