Localizer and Glide Slope Service Volume

The 2002 FAR/AIM defines the service volumes for the localizer and glide slope:

	FAR/AIM	Flight Trainer Implementation
Glide slope width	1.4 degrees wide, 0.7 degrees above and below nominal angle above horizontal.	1.4 or +/- 0.7 degrees
Glide slope angle	nominally 3 degrees	3 degrees
Localizer width	between 3 and 6 degrees to provide a 700 foot width at the threshold for a full scale deflection.	uses 18 degrees or 3X the maximum. This is done to provide enough width to provide a reasonable working area to position the plane
Localizer inner service volume	35 degrees each side of centerline to 10 nautical miles	as specified
Localizer outer service volume	10 degrees each side of centerline to 18 nautical miles	as specified

The Flight Trainer implements the Localizer Service Volume as indicated above and shown below.

Specifics about the Localizer implementation are:.

The front course is indicated by the darker yellow and blue and inward pointing arrow - Figure 1.
The back course is indicated by the lighter yellow and blue and the outward pointing arrow - Figure 1.
The two arcs at 18 and 10 miles are the service volumes described above.
The innter circle is implement by the Flight Trainer to allow for the "radiated" signal close in and make it easier on the user to position the plane close to the station.
In the portions of the circle outside of the arc of the inner service volume, the lateral deflection will be full scale to the appropriate side - Figure 2 as shown in green for one side. The same applies to the other side.
When within inner and outer service volumes, the localizer will be on.
When outside the outer service volume, the localizer will be flagged off - Figure 3 as shown in green.
When inside the inner service volume radius but outside 35 degrees either side of the centerline, the localizer will be intermittent and flag switch between on and off.

Specifics about the glide slope implementation are:

The glide slope angle is the nominal specified by the FAR/AIM.
The glide slope is flagged off when the plane is in the back course area.
The glide slope is flagged off when the plane is outside the Localizer service volume defined above.

Figure 1.

Figure 2.

Figure 3.