Be ready for a few acronyms!
The FAA has recently begun adding GPS routes into ILS
procedures, which in my opinion is a great thing! This combination of GPS and
ground-based navigation allows for more flexibility for routing and easier flyability
among other benefits. Here's what I'm talking about, see this example at
Statesville, NC (KSVH).
If you're not familiar with TAA's (Terminal Arrival
Areas), they are on many RNAV (GPS) approaches already but are just now being
added to ground-based approaches as well:
TAA's allow you to be cleared for the approach anywhere
within the depicted area, usually within 30nm of the fix shown (in this case
PEGTE). The minimum altitude you must be at depends on distance and what your
course is to that fix. So, in this example, coming from the west the minimum
altitude is 4300 until within 6 nm of PEGTE, then 3400. From the east it's
simpler, just 3400 all the way to PEGTE. Also notice that any course to the fix
from 195 clockwise to 015 is considered a "NoPT" segment, so you can
skip the depicted Hold-in-lieu-of-Procedure-Turn (HILPT). From the western half
of the TAA you are still required to execute the HILPT in the example.
Another benefit of the TAA is that they do not require a
VOR-based route into the procedure. Notice that the IF, PEGTE, is not anywhere
on the Low Enroute chart (though there are some crossing radials, it's not on
an airway). The TAA gives you the flexibility to be on a published segment of
the approach, flying direct to PEGTE from anywhere within 30nm.
Another example is that at Rock Hill, SC (KUZA).
This one has a complete "T" setup of IAFs and
the TAA to match. Unlike at KSVH, this allow you to come from essentially any
direction and avoid flying the HILPT. If you're coming from the northwest,
you'd fly direct to GUCRE, then be on a NoPT segment after reaching GUCRE headed
to CONEL. The same idea with TAGCU from the northeast. From the south, you'd
fly to CONEL and then proceed straight-in after reaching it.
One caution - if like in many airplanes, you're
displaying both your GPS and ILS guidance on the same CDI, make sure to switch
the CDI source as you reach the IF.
Another great benefit of a TAA is that ATC can clear you
for the approach from a long way away. In order for ATC to clear you for the
approach, you are required to either be on radar vectors OR established on a
published segment of that approach. Since being within the TAA is considered to
be on a published segment of the approach, you might be 28nm from GUCRE and
hear a very simple "N123, Cleared ILS Y runway 2 approach"!
Now, many of these TAA-to-ILS approaches probably also
have an RNAV (GPS) approach to the same runway with LPV minimums. In that case,
if you have a WAAS-equipped GPS receiver, you'd probably just fly the GPS
approach. But sometimes the minimums aren't quite the same, or there isn't an LPV
approach to that runway for various reasons, so the TAA-to-ILS might be a
benefit even with a WAAS receiver. If you AREN'T WAAS equipped, then the
TAA-to-ILS is great, because it doesn't take a WAAS receiver to fly it!
I expect to see more and more of these published as time
goes on. Let me know if you see a new one!
(Acronym count: 12. I guess that's not too
bad.)
