t-39 - Chief of Naval Air Training
t-39 - Chief of Naval Air Training
t-39 - Chief of Naval Air Training
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APPENDIX E<br />
INSTRUMENT LANDING SYSTEM (ILS) BASICS<br />
You will be introduced to the ILS approach in the T-<strong>39</strong> syllabus. The following is<br />
information taken from the Aeronautical Information Manual (AIM) and the T-<strong>39</strong> NATOPS to<br />
assist you in preparation for ILS approaches. The T-<strong>39</strong> and most other aircraft have ILS. You<br />
will be expected to know the basics <strong>of</strong> the ILS/Localizer system.<br />
1. ILS/Localizer/Glideslope<br />
The ILS is a precision approach similar to the PAR, with the exception <strong>of</strong> a final<br />
controller using radar to verbalize azimuth and glideslope information, this information is<br />
displayed on the aircraft flight instruments for you to interpret. An ILS consists <strong>of</strong> two<br />
components, the localizer and the glideslope. The localizer provides the azimuth (centerline)<br />
portion <strong>of</strong> the ILS. Glideslope must be available, otherwise an approach must revert to the<br />
localizer minimums (higher than an ILS). The glideslope is normally 3º but can be higher<br />
depending on local terrain (Refer to minimums section in the front portion <strong>of</strong> the approach<br />
plates). Corresponding VSI/VVI information for a given glideslope at a given airspeed can<br />
be found on the inside back cover <strong>of</strong> any approach plate.<br />
2. ILS Minimums<br />
There are three categories <strong>of</strong> ILS minimums, but the T-<strong>39</strong>G is only qualified for<br />
Category-I minimums. For general knowledge, the three categories are:<br />
• Category I - 200 - 1/2 (2400RVR)<br />
• Category II - 100 - 1/4 (1200RVR)<br />
• Category III - 0 - 0<br />
3. ILS/Localizer Transmitter<br />
Your Approach plate will specify the ILS frequency (see any ILS approach plate). It will<br />
be contained in a box that has an 'I' preceding the airfield's 3 letter identifier (such as: I-PNS<br />
or I-MOB). If the box has a TACAN channel, the ILS provides DME (see Mobile Regional).<br />
If the ILS does not have DME and a TACAN is co-located on the field (see Gulfport), then<br />
you will have to select the TACAN channel and the ILS frequency. TACAN DME is<br />
displayed on the EHSI and DME associated with the VHF NAV (VOR/LOC) frequency (if<br />
available) is displayed on the digital DME gauge.<br />
4. Marker Beacons (Fan Markers)<br />
Marker Beacons are available with some ILS/Localizer systems. Ordinarily there are two<br />
Marker Beacons associated with an ILS: the Outer Marker (OM) and the Middle Marker<br />
(MM). The Outer Marker always transmits at 400 Hz, and is indicated by an aural signal and<br />
E-1