BY ORDER OF THE SECRETARY OF THE AIR FORCE AIR FORCE ...

AFMAN 11-217 V1 3 JANUARY 2005 93
Figure 6.2. Normal Localizer Signal Coverage.
6.7. Microwave Landing System (MLS).
6.7.1. Description. The MLS provides precision navigation guidance for exact aircraft
alignment and descent during an approach to a selected runway. It integrates azimuth
(AZ), elevation angle (EL), and range (DME) information to provide precise aircraft
positioning. The components of an MLS are similar to an ILS. Instead of a glide slope
antenna, the MLS has an elevation station, and instead of a localizer antenna, it has an
azimuth station. The MLS also has a precision DME (DME/P) transmitter. The DME/P
signal is more accurate than traditional DME.
6.7.1.1. NOTE: An additional conventional-type DME source may be used to
construct the instrument approach procedure; however, this DME is not considered to
be a “system component.”
6.7.2. Ground Equipment Location (Figure 6.3). MLS is normally installed in a
configuration similar to ILS; however, it is possible, if necessary because of limited
space, to install all of the components together. One example of this type of collocated
configuration might be a hospital’s heliport. In a standard airfield installation, the MLS
azimuth transmitter is usually located between 1,000 and 1,500 feet beyond the departure
end of the runway along the runway centerline. The elevation transmitter is normally
located 400 feet from the runway centerline near the approach threshold. The DME,
which provides range information, is collocated with the azimuth transmitter.
6.7.3. Displays. MLS displays are virtually identical to the ILS. Both lateral and vertical
MLS guidance may be displayed on conventional course deviation indicators or