The CDI may be used for tracking all radials on the approach (e.g., initial inbound radial, final approach
When executing a TACAN/VOR DME approach and before reaching the IAF, set the final approach
course into the course select window of the HSI. At the IAF, intercept and maintain the approach course
as published. Lower the nose and accelerate to 250 KIAS. At 250 KIAS, reduce power to flight idle.
Adjust nose attitude as required to maintain 250 KIAS and 4,000 to 6,000 fpm (approximately 10 degrees).
Extend speed brakes as necessary for increased rate of descent. Report departing the IAF if requested.
Start penetration turn 2.5 nm DME from the arc. At 5 to 7 nm prior to the FAF slow to 200 KIAS.
Configure the aircraft for landing 3 to 5 nm prior to the FAF and perform landing checklist (speed brakes
retracted). Conform to all course, altitude, and DME instructions on the approach plate. Lead level off
from penetration by 1,000 ft if VSI pegged at 6,000 fpm.
At the FAF, start the clock, extend speed brakes, report landing checklist complete on the ICS and make
gear down call to ATC. Descend to the MDA and start looking for the runway while monitoring your DME
for the MAP. Plan your descent to be in level flight at the MDA prior to reaching the MAP. From the FAF
maintain precise course, speed, and rate of descent control. Do not exceed 1,000 fpm. Keep heading
changes small so you dont chase the final approach course on the CDI.
When you reach the MAP, if you dont have the runway environment in sight or determine that a safe
landing is not possible, execute a missed approach.
The ILS approach is a precision approach in which you are provided precise glideslope, azimuth (course),
and range information. The ILS (Figure 38) is composed of three elements; the localizer transmitter, the
glideslope transmitter, and marker beacons. As with any approach, you should back up the ILS approach
with any other available NAVAIDs.
The localizer transmitter provides azimuth information to the CDI in the HSI and azimuth deviation bar
(ADB) in the ADI for maintaining alignment with the approach course. The localizer signal has a
maximum range of 18 nm from the station, if you are within 10 degrees either side of the course
The glideslope transmitter provides glideslope information to the GS pointer in the HSI and glideslope
deviation bar in the ADI. Glideslope transmitters have a normal range of approximately 10 nm, if you are
on or near the localizer course. However, at some locations the glideslope has been certified for an
extended service volume which exceeds 10 nm.
NOTE: Glideslope is defined as the descent angle assigned to an approach to a given runway for obstacle
clearance and/or signal reception. Glidepath is defined as the portion of a precision approach that
intercepts the azimuth of an ILS approach or the FAC of a PAR approach.
When overflown, the three marker beacons (outer, middle, and inner) provide a distance (range) reference
by sounding an aural tone and illuminating one of three marker beacon lights on the instrument panel.
Although there are a maximum of three marker beacons, most ILS approaches do not have all three, and
some do not use them at all. If beacons are not present, cross-radial fixes, DME or radar is required. The
outer beacon usually marks the FAF and will often indicate the point of glidepath intercept. The middle
marker denotes the vicinity of the DH for category I approaches (the T-45A is equipped for Category I) and
progress points for categories II and III. You will cross the middle marker approximately half a mile from
the runway, at 200 ft AGL (this may vary depending on local terrain and minimums). The inner marker
denotes the DH for category II approaches and is a progress point for category III approaches. You will
usually cross the inner marker at 100 ft AGL.