What does the term "backcourse"mean

When backcourse is available, it means a single localizer part of a localizer ILS precision approach equipment  (horizontal navigation) is being used from the opposite runway direction. If it has a glide slope transmitter as in a full ILS you may receive false incorrect indication for the vertical profile which can not be used in a back course approach.

 

The horizontal indicator of the gauge will operate in reverse indication of which way to center on the extended localizer center requiring correction in the opposite direction. Some aircraft have a BC switch to correct this on the gauges and autopilot.

 

Back courses are avoided at most airports.

 

In FS default airports have backcourse incorrectly enabled on all localizer/ILS navaids. Where in FS the same frequency is used for those navaids at each runway end you will receive the incorrect navaid unless within about two degrees of the extended runway center line. This can be checked by listening to the Morse code identifier or if equipped the identifier on the navigation display. Where this condition exists an airport editor such as ADE9X freeware or AFX payware can be used to correct back course transmission enabled in error. These editors do not have have limitations of AFCAD 221 that can corrupt or strip information from add-on airport scenery from the bgl type file used for this portion of the scenery.