What is the horizontal and vertical fields of view for a VASI and a PAPI approach system as you come in to land?
This information is for the US, taken from FAA Order 6850 - Visual Guidance Lighting Systems.



VASI (2 bar VASI for illustration, but other configurations exist)

a. Layout

  

b. Aiming


  The two-bar VASI system shall have the upwind bar aimed at three
  degrees and the downwind bar aimed one-half degree lower at 2.5
  degrees; however, where necessary to provide obstacle clearance, the
  downwind bar may be aimed at 2.75 degrees.


c. Glide (vertical) path angles

  

d. Horizontal field of view: 10°


  Determine the minimum aiming angle by plotting all objects within an
  area  established by two lines each diverging at 10 degrees from
  runway centerline extend to 4 nautical miles, and starting at the
  runway centerline at the number one bar.  A line drawn from the runway
  centerline at the number one bar at an angle that will clear the
  highest object by not less than one degree establishes the minimum
  aiming angle.  This line and a horizontal line perpendicular to the
  runway centerline at the number one bar (downwind) establishes an
  obstruction - clear plane 10 degrees (6 degrees in special
  applications where 10 degrees is not obtainable) on both sides on the
  extended runway centerline.  The obstruction clear plane starts at the
  number one bar and extends outward from the threshold for four
  nautical miles.  In addition, the minimum aiming angle shall be within
  the glide path limitations of paragraph 4. When less than 10 degrees
  are used for determining the obstruction-clear plane, issue a NOTAM
  and request publication in the Airport/Facilities Directory.




PAPI 

a. Colocation with ILS glideslope


  When siting PAPI on a runway with an established electronic glide
  slope, the PAPI visual approach path should coincide, as much as
  possible, with the one produced electronically.  To accomplish this,
  the PAPI is placed at the same distance from the threshold as the
  virtual source of the electronic glide slope within a tolerance of ±30
  feet (±10 m).  The PAPI is aimed at the same angle as the electronic
  glide slope.


b. Layout

  

c. Aiming


  The visual glide path angle is the center of the on-course zone, and
  shall normally be 3 degrees when measured from the horizontal.


d. Glide (vertical) path angles

  

e. Horizontal field of view: 10°


  The PAPI obstacle clearance surface is established to provide the
  pilot with a minimum clearance over obstacles during approach.  The
  PAPI must be positioned and aimed so that no obstacles penetrate this
  surface.  The surface begins 300 feet (90 m) in front of the PAPI
  system (closer to the threshold) and proceeds outward into the
  approach zone at an angle 1  degree less than the aiming angle of the
  third LHA from the runway.  For a 3 degrees glide path and 20 minutes
  separation between LHAs, the third LHA from the runway would be aimed
  at 2 degrees, 50 minutes elevation.  The surface extends 10 degrees on
  either side of the runway centerline extended, and extends 4 statute
  miles from its point of origin.  The surface is shown graphically in
  figure 5-4.  If a site survey determines that there is an obstacle,
  which penetrates the obstacle clearance surface and cannot be removed,
  then the glide path angle must be changed or the PAPI system moved
  further from the threshold.  By moving or re-aiming the PAPI, the PAPI
  obstacle clearance surface is repositioned so it will not be
  penetrated by an obstacle.