$^{ }$  25  N o rm  a l A  p p r  o a c  h 25 N o rm a l  A p p r o a c h  25 25  25  N o rm a l  A p p r o a c h  25  N o rm a l  A p p r o a c h  Downsloping runway  Upsloping runway  Upsloping runway Downsloping runway  Wider runway Narrower runway  Wider runway Narrower runway  Normal approach  Approach due to illusion  Runwa width illusion  • narrower-than-usual runway can creat an illusion that the aircraft is hiGLYPH<df00>her than it actually is, leadinGLYPH<df00> to a low er approach. •  wider-than-usual runway can creat an illusion that the aircraft is lower than it actually is, leadinGLYPH<df00> to hiGLYPH<df00>her approach. Runwa slope illusion  • A do wnslopinGLYPH<df00> r unway can create the illusion that the aircraft is lower than it ac tually is, leadinGLYPH<df00> to a hiGLYPH<df00>her appr oach. • A upslopinGLYPH<df00> runway can create the illusion that the aircraft is hiGLYPH<df00>her than it ac tually is, leadinGLYPH<df00> to a lower appr oach. Figure 17-7.  Runway illusions.  diagrams and the Chart Supplement U.S. (formerly  Airport/Facility Directory) for information on runway  slope, terrain, and lighting.  2. Make frequent reference to the altimeter, especially  during all approaches, day and night. 3. If possible, conduct an aerial visual inspection of unfamiliar airports before landing. 4.  Use Visual Approach Slope Indicator (VASI) or  Precision Approach Path Indicator (PAPI) systems  for a visual reference, or an electronic glideslope,  whenever they are available. 5.  Utilize the visual descent point (VDP) found on many  nonprecision instrument approach procedure charts. 17-11 