When installed with the ILS, what can DME be used for according to the approach procedures?

Using DME (Distance Measuring Equipment) in conjunction with an Instrument Landing System (ILS) is specifically intended for certain functions critical to approach procedures. When installed with the ILS, DME can provide not only the distance to the runway but also aid in determining the aircraft's position relative to the glideslope.

In this context, when DME is used "in lieu of the OM" (Outer Marker), it serves as a substitute for the traditional OM, which provides a specific point at which pilots could expect to start their approach descent. The DME can effectively perform the same function by providing distance information, allowing pilots to identify the correct point to initiate their descent.

This capability makes DME a valuable tool during ILS approaches, ensuring that pilots have accurate positioning data to facilitate safe landings, especially when conventional markers may not be in service or offering reliable information. Thus, utilizing DME in this way enhances safety and precision during approaches.