1.—(a) Subject to sub-paragraph (b), the holder of a licence which includes ratings of 2 or more of the classes specified in paragraph 2 of this Schedule shall not at any one time perform the functions specified in respect of more than one of those ratings.
(b)the functions of any one of the following groups of ratings may be exercised at the same time:
(i)the aerodrome control rating and the approach control rating;
(ii)the approach control rating, the approach radar control rating and the area radar control rating; except that the functions of the approach control rating shall not be exercised at the same time as the functions of the approach radar control rating if the service being provided under the latter is a surveillance radar approach terminating at a point less than 2 nautical miles from the point of intersection of the glide path with the runway.