4-76  The LDA is not aligned with the runway. Straight-in  minimums may be published where alignment does  not exceed 30° between the course and runway. Circling  minimums only are published where this alignment  exceeds 30°.  The LDA is of comparable use and accuracy to a localizer  but is not part of a complete ILS. The LDA course usually  provides a more precise approach course than the similar  simplified directional facility (SDF) installation, which may  have a course width of 6° or 12°.  In cases where an ILS is installed, a back course may be  available in conjunction with the localizer. Like the localizer,  the back course does not offer a glideslope, but remember  that the back course can project a false glideslope signal  and the glideslope should be ignored. Reverse sensing  occurs on the back course using standard VOR equipment.  With a horizontal situation indicator (HSI) system, reverse  sensing is eliminated if it is set appropriately to the front  course. [Figure 4-60]  same approach without vertical guidance stemming from  the glideslope. A localizer is always aligned within 3° of the  runway, and it is afforded a minimum of 250 feet obstacle  clearance in the final approach area. In the case of a  localizer DME (LOC DME) approach, the localizer installation  has a collocated DME installation that provides distance  information required for the approach. [Figure 4-59]  Localizer-Type Directional Aid (LDA)  Localizer Back Course  Figure 4-47. Simultaneous independent close parallel approach example using ILS PRM approaches.  NO TRANSGRESSION ZONE (NTZ) 26L 8R 26R 8L Intercept glideslope at 3,200 feet. NTZ begins where there is less than standard separation.  Radar monitoring provided to ensure separation during simultaneous approaches. A breakout will be directed if an aircraft enters the NTZ. Radar monitoring provided to ensure separation during simultaneous approaches. A breakout will be directed if an aircraft enters the NTZ. Standard lateral or vertical separation between aircraft on parallel localizers prior to the beginning of the NTZ. Runway centerlines spaced less than  4,300 feet apart, radar monitoring and  PRM procedures required 3,200 feet 2,200 feet Intercept glideslope at 2,200 feet Normal Operating Zone (NOZ)