AOPA Pilot Magazine - June 2015 - 10

LETTERS

FROM OUR APRIL 2015 ISSUE

Proficiency & Efficiency
Readers weigh in on the assortment of information in our P&E section,
which offers technique tips, ownership ideas, and ways to stay proficient.
I completely agree with the article "Keep it Clean: Give Your
ils basics
Aircraft a Bath." Too many wonderful airplanes sit on the ramp
(even in hangars) with weather
stains, bugs, and accumulated
dirt from uncaring owners who
treat their airplanes like cheap
lawnmowers. A quick wipedown after every flight not only
helps preserve the airplane's
finish, but also serves as a good
postflight inspection.
One word of caution. There
are more and more fabric-cov"Not all Category III ILSs require an autoered airplanes out there (LSAs,
for example) and there is a very pilot with autoland capabilities. At Horizon
important item: Check for and Air, a West Coast regional airline, we've
avoid silicon ingredients. Do not
use cleaners, soaps, or sprays been hand-flying CAT III approaches using
that contain silicone! Silicone a Head Up Guidance System for more than
is not paint-shop friendly. If
you ever have to make a repair 20 years. Originally certified in our DHCto your aircraft's fabric, the sil- 8-100s, we are currently flying Q400s to
icone will have leached into
the paint and fabric weave. You CAT III minimums of 50 feeet DH and 600
don't see this when you spray RVR. Flight Safety Seattle has two Q400
it on or apply it, and in fact, it
seems to clean just fine. But it simulators equipped with HGS; you should
is working its way into the very go give it a try, it's easier (and more fun)
weave of the fabric and deep
into the silver coating. This is than it sounds!"
Tom Berning
not as important on aluminum
AOPA 664211, Sandy, Oregon
airplanes, as you can sand the
paint (and silicon) all the way
down to the aluminum (see
"P&E: Ownership," on page 80).
Skip the simple/cheap
cleaners items such as Pledge,
What certificate are you training for now?
or some of the car cleaners that
1.5%
have silicon in them. Look for
Sport
9%
9%
paint-shop friendly cleaners
17%
Recreational
1.5%
like Flitz to clean your fabric
Private
24%
24%
aircraft.
17%
P&E

on instruments

Riding the pipe to 200 and a half
BY THOMAS A. HORNE

Guidance and coveraGe

the iLs uses paired frequencies to
provide an exact approach path for alignment with the runway centerline, as well
as precise descent guidance along that
path. the localizer part of the iLs signal gives left-right steering commands
so you can stay on the signal's centerline;
the glideslope signal gives similar up and
down commands. the pilot-and/or the
autopilot-responds to these commands
by observing course deviation indicator
(CDi) deflections and making small heading and pitch corrections so as to keep
both localizer and glide slope needles
centered. Fly the centered needles "down
the pipe," and you'll find the runway dead

ahead, assuming a no-wind condition.
Large crab angles of the sort needed to
compensate for healthy crosswinds may
require that you look to one side or the
other to spot the runway. that's well
worth remembering on windy nights, or
whenever visibilities are restricted by
fog, rain, or other restrictions.
Localizer and glideslope signals have
limited ranges. At most, reliable signals
extend as far as 18 nautical miles or so,
but that's only for localizer guidance
within 10 degrees of the course centerline. Closer to the runway-out to about
10 nautical miles from the runway-signals are good within 35 degrees of the
course centerline. What does this mean?
it means that if you are disoriented and
outside these coverage areas, you won't
have reliable iLs signals. or, in the worst
case, you may be tricked by false signal
"lobes" that mimic inbound-path CDi
indications.

TyPIcAL ILS cOverAge volumes for accurate
reception of localizer and glideslope signals.
cdI one-dot deflections show the typical
signal sensitivities at the outer and inner
markers. compared to the localizer, the
glideslope is much more sensitive to
deviations from the proper glidepath. The
illustration gives general information; signal
qualities can vary among Ils installations.

iniTial procedures

Like all iFr procedures, the key to shooting a good iLs begins with preparation,
anticipation, and staying ahead of the
airplane. once you've received your
approach clearance, tune in the iLs frequency, identify it, check that the marker
beacon lights are working, and get ready
to intercept the localizer. often, in areas
where there's adequate radar coverage,
the usual drill is for AtC to vector you to
the localizer, at a point somewhere outside the final approach fix. (in nonradar
and/or nontowered environments, "full"
procedures can be the rule, leaving you to
navigate to the iLs' via feeder and initial
fixes on your own.)
take a good look at the approach
chart, noting everything-but paying

charles floyd

To many insTrumenT- rated pilots,
the instrument Landing system (iLs)
approach rates as the gold standard. iLs
approaches have been reliably providing precision guidance to hundreds of
runways around the world for the past
70-odd years, so when the weather turns
seriously rotten it's the approach that
pilots are most apt to request. that's reason enough for instrument-rated pilots
to stay proficient flying iLss, and for the
noninstrument-rated to gain a working
knowledge of the basics-just in case.
the big value of the most common
Category i iLs approach is its ability to
provide both lateral and vertical guidance to runways experiencing weather as
low as 200-foot ceilings and/or one-halfmile visibilities. (Actually, the visibility
is measured by runway visual range-
rVr-transmissometers, which measure
visibility along a portion of the runway's
length.) However, those minimums are
generalities. nearby terrain or obstacles
can push minimums higher, for example.

special interest to minimum altitudes. You
should have checked during the preflight
briefing to learn if any components of the
iLs are inoperative. the glideslope may
be out, for example, in which case you'll
be shooting a localizer-only approach
with no vertical guidance-and thus have
to comply with higher minimums. Call up
the weather on the AWos or Atis frequency, if the airport has one. otherwise,
a quick call to AtC or Flight Watch may
give you the latest weather.
most pilots now have GPs, moving
maps, and flight directors/autopilots-all
of which provide great safety advantages.
even so, mistakes can happen, and the

stakes are high when flying approaches
in low ceilings and visibilities. turn your
CDi's heading card to the inbound course.
Although this won't affect your course guidance (the iLs only emits accurate tracking
cues for a single course, quite unlike a
Vor's radials) it helps keep you oriented
to the final approach course as you intercept and track inbound to the runway.
By the way, is your primary nav unit
in GPs mode? it shouldn't be, if you're
on vectors. the unit should be ready to
receive VHF transmissions from the
iLs antenna, so be sure it's in CDi or
VHF mode. Check your unit's operating manual for specific switching and

80 | AOPA PILOT April 2015

Jon Engle
AOPA 1108508
Hollywood, South Carolina

10 | AOPA PILOT June 2015

Commercial
Flight Instructor
Airline Transport Pilot

other procedures. GPs/navcoms don't
have standardized controls or protocols,
unfortunately, so it's up to you to know
your equipment inside-out.
Have a second navigation receiver?
Great. use it for tracking and cross-bearing information for any applicable initial
approach fix feeder routes, fixes along
the final approach course. Having a second nav source set up for guidance on
the missed approach is another good
idea. You don't want to be spinning dials
when you're at 200 feet agl, don't have
the runway environment in sight, and are
reconfiguring the airplane for a climb on
the missed approach procedure.
www.aopa.org/pilot AOPA PILOT | 81

31.5%
17%
17%

31.5%

Hypoxia knockout

I have enjoyed the articles on
hypoxia. They are very informative and explain many
dangers of low oxygen, but I
have not seen anything about
the safe oximeter percentage
levels we should use.
When I fly my Cirrus crosscountry I generally fly between
8,000 feet and 14,000 feet, so
we use oxygen a few times a
year. When I go above 9,000
feet I monitor my level with
my oximeter and when it gets
close to 90 percent, we put on
the oxygen cannulas and adjust
them so our levels are about 90
percent to 92 percent. This
level seems to work fine but
I don't know what level we
should be using, as I have not
found any official information
on this. I am 79 years old but in
good health. My sea-level reading is about 98 percent.
I would like to suggest you
publish an article giving us
details on the use of oxygen in
small planes and the oximeter
percentage levels we should
be using. I am sure other pilots
would also appreciate the
information and confirm if
their procedures on the use of
oxygen are correct.
Ed McDonald
AOPA 6358216
Miroma Lakes, Florida

See our May issue "P&E: The
Air You Breathe" for more
information.-Ed.

ILS basics

It is nice to see an informative
article on ILS signals in space,
as we refer to them.

http://www.aopa.org/pilot

AOPA Pilot Magazine - June 2015

Table of Contents for the Digital Edition of AOPA Pilot Magazine - June 2015