Figure 4-40. ILS final approach segment design criteria.  Figure 4-41. ILS approach categories.  4-70  CAT II  100  0  150  700  Runway visual range (feet)  1,200  1,800  2,400  200 Decision height (feet AGL) CAT IIIc  CAT IIIb  CAT IIIa  CAT I  The lowest authorized ILS minimums, with all required ground and airborne systems components operative, are:  CAT I - decision height (DH) 200 feet and runway visual range  (RVR) 2,400 feet (with touchdown zone and centerline lighting.  RVR 1,800 feet).  CAT II - DH 100 feet and RVR 1,200 feet.  CAT IIIa - No DH or DH below 100 feet and RVR not less than  700 feet.  CAT IIIb - No DH or DH below 50 feet and RVR less than  700 feet but not less than 150 feet.  CAT IIIc - No DH and no RVR limitation.  NOTE: Special authorization and equipment are required  for CAT II and III. 