ILS Approach To KIAD Runway 1L - Coupled
Approach
Unless
you have had some practice flying ILS's and are familiar with the various
terms used you might find this all a little confusing.
So take a little time to aquaint yourself with the various instrument options and uses.
For example
I'll use an approach to RWY 1L @ Dulles (KIAD) so that you can orientate
yourself. The aircraft I am using for this illustration is a 767 with
a cockpit like the default 777 with a few variations so load your 777 as
the small gauges on the 747 hurt my eyes.
ILS freq
RWY 1L 111.30
OBS or
ILS course 011*
Check out the IAP Below
The NAV/GPS
knob should be in the NAV position not in the GPS position as the steering
computer is getting input from NAV1 when tuned to the appropriate or correct
ILS frequency, in this case 111.30
Now having
said that we should back up here a tad to the phase of flight where you
are setting up for the approach.
You can
start by positioning yourself on a straight-in approach at least 20 miles
from touchdown at 4000ft. This would give you ample time to set things
up and have your airplane configured for the approach/landing
.
AUTOPILOT PANEL
To use
any of the Autopilot functions on the Autopilot panel the Autopilot Master
switch(A/P) must be in the ON position indicated by the integral
green light.
The autopilot
ON switch(A/P) puts the autopilot in an acceptance mode so to speak.
You can
also select any function, say HDG hold directly and the A/P Master will
automatically be engaged however that depends on the particular aircrafts
autopilot setup in this 767 it can be selected either way.
The
following describes the various switches and windows on the Autopilot
panel.
WINDOWS
1.
CRS Course or CRS selector dialed in 1-degree
increments.
2.
HDG Heading selector window
3.
A/T / MACH Speed Hold
4.
ALT Altitude Selector
5.
VS - Vertical Speed selector
Autopilot ON/OFF or selector switches
(for
this illustration the Flight Director will be omitted)
And all references to the Autopilot will simply
be called A/P.
Looking
from left to right:
AP NAV HDG APR SPD MCH ALT VS
AP A/P Master Switch (in pic it is on)
NAV
NAV Hold (Enables
A/P to track and maintain a desired VOR radial or can be
used to track A Localizer course or LOC as set in
the NAV1 Radio.
HDG
Heading Hold
switch. When selected the A/P will fly the heading as set by the
Pilot in the heading selector window. In the pic above
it shows ON with a
selected heading Of 011* . The aircraft will maintain
a constant heading, but
will not track a radio Aid, VOR or ILS.
APR Approach hold switch. Sometimes
labeled APP This function is used by the A/P
to intercept and fly the ILS/GS. Dependant on by freq
set in NAV1 ( More on
this later )
SPD
- Speed Hold IAS or Indicated Air Speed
MCH
MACH Speed Hold
ALT
Altitude Hold
switch. Enables the A/P to maintain a set altitude as set in the
Alt Window ( In pic above the set altitude is 4000ft
and is ON)
VS - Vertical Speed hold
Small
checklist
A/P .......................... ON
Alt
Hold ....................
ON
HDG
Hold ..................;
ON
***(Setting
these three will allow you to compatibly set the rest of your cockpit
for the approach and subsequent landing as the aircraft will maintain
heading and altitude just keep an eye on airspeed as you get setup.
NAV1
Tuned to ............... 111.30 (ILS RWY 1L)
CRS course
SET .............. 011*
APR .............. .........ON
Autopilot
should begin tracking the Localizer and drop the heading reference. This
action will be evident by the HDG light going off indicating that the
input to the A/P is from Nav1 and displayed as a Magenta line in the middle
of the PDI.
Select
Flap and Gear as required
Initial ILS Cpture
Here is a small
diagram showing the airplane inital altitute at 4000ft( indicated by red
arrow numbered 1-) intercepting the glide slope from below. Attempting to
intercept the GS from above will result in no capture, although the LOC can
be tracked. Remember the GS is projected at 3 degrees( there are also variations
on this angle) but for this discussion 3 degrees is used.
Initial Descent
Once the GS is intercepted
the the A/P drops the ALT hold reference as height now is being referenced
to the glidepath and adjustments in pitch attitude will be noticed, the
ALT hold light will go off and the aircraft will start down the Glidepath
to the runway all this occurs in milliseconds.
Here the A/P coupled
to the APR function has established the aircraft on the ILS.
Note that the ALT hold
light is extinguished and IVSI shows a descending trend. You can now set
your go around or missed approach altitude of5000ft in you ALT window
as published in the IAP.
The GS indicator shows
slightly below Glidepath as this is the initial descent on the GS.
(This
initial deviation or rate of descent as seen on the IVSI, in this picture,
of
almost
1400FPM is not acceptable. In real world transitions are smooth so as
not to alarm your passangers. This is an error in flight simulator 2002
I had not seen this error in fs2000 or FS98.
Note that the landing
gear is in the down/locked position with only finial flap selection to
come. Also DME is now 10.
Fully Established
and configured for landing
In this next picture
the Altitude is now reducing past 3100ft with a VS of 700fpm which is good.
Airspeed is about 150kts.
Final flap has been set and slightly below glidepath or 1/2dot.
Landing Checks
are complete
Descending out of 800ft
at 700fpm airspeed stable at 150 +/- 4kts in the slot
1.8 DME
This hopefully will address
some questions that you may have but I suspect not all as there is still
a huge amount of information that is still not covered here.
There are many, many
factors that combine themselves, relate, react, work in concert with and
so on to produce what seems like a simple action in this instance, flying
an ILS. Knowing what takes place when you push
a single button is more complex than just on or off. To some people that
is the boring part having to kmow all this stuff why not just turn and burn
Flight Simulator is a
great tool and is a tremendous amount of fun.
Have fun,
Douglas