Besides seeking information on the weather, the pilot also relies on the very important information contained within aeronautical publications. These tell the pilot of the availability of radar, radio frequencies, landing and weather minima, glide slope angles, and the types of approach available at a particular runway. The terminal or approach plates contain further information. They give a runway and airfield pictorial presentation of the obstructions surrounding the field, the approach lighting, and the relative position of the NAVAIDs. Additionally, they give the length and width of the runways, as well as information on rates of descent and ground speeds. All of this may be needed by the pilot in order to execute the approach.As previously mentioned, there are a variety of approaches used around the world at different airports. These approaches are divided into two major categories: precision and non-precision. Non-precision approach procedures are intended to provide an orderly and safe flight progression from the en-route structure to a position at an aerodrome from which a visual landing can be made. VOR, VORTAC, NDB and airport surveillance radar (ASR) are all examples of non-precision approaches. The only precision approaches available anywhere are the precision radar approach (PAR), the instrument landing system (ILS) and the new microwave landing system. Of these three, the ILS is the most prevalently used.On a precision radar approach，the controller interprets radar displays and transmits course and glide slope information to the pilot. The pilot then maneuvers the aircraft as directed by the controller in order to arrive at a position from which to land safely.The instrument landing system (ILS) is designed to provide an approach path for exact alignment and descent of an aircraft on its final approach to a runway. An ILS consists of a highly directional localizer and glide slope transmitter with associated marker beacons and at some sites，distance measuring equipment (DME). There are three ILS categories: category I equipment gives guidance information down to a decision height (DH) of not less than 200ft, while category Ⅱ gives a DH of not less than 100ft, and category Ⅲ ILS approach are subdivided into three groups, all of which allow descents to touchdown, since decision height are not specified.1.To execute an approach, the pilots need to consult with （ ） ．