"ShaneH"
External Forum User
shs@hotmail.com
Posted on:
Apr 22, 2003, 12:43 AM
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Re: What is ILS and how is it used?
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Thanks Will for the very detailed reply, very much appreciated!
The number of 200kts and 100kts I picked at random, just to illustrate my
problem. Most the time I fly and land without autopilot, usually military
jets, but on occasions I tried the autopilot's APPR. I get it to work maybe
20% of the time. I thought the FS2002 autopilot is more effective, (would
both keep the plane on the glideslope and hold the speed) but your and
others explanations tell me that's not always the case. But its not a mayor
issue for me, I'm quite happy to land manual most of the time. Just wanted
to know what I'm missing here.
ShaneH
"CHANGE username to westes" <DELETE_westes@uscsw.com> wrote in message
news:tw6dnX5cDuTrJTmjXTWcqw@giganews.com...
> Assuming you have Autopilot configured to APR, coming into the ILS from
> below, the APR mode in the autopilot should automatically compensate for
> airspeed by adjusting the stabilizer. Thus, it's possible to follow the
> glideslope down at many different airspeeds, and a good autopilot will
> continue to track the ILS.
>
> Some general observations:
>
> 1) NEVER try to catch the ILS from above. It just doesn't work reliably.
> To make it work you end up having to do a radical dive from above to well
> below the glideslope, then even out and catch it from below. This would
be
> aerobatics, and probably your controller would not be amused. :)
>
> 2) You are really well served by buying the Jeppesen SIM Charts 2.0
add-in,
> available directly on the Jeppesen web site. You need to buy three $29
> licenses to activate the entire world, I believe. Rather than just fake
it
> and look for an ILS beam in the GPS, it's a lot more interesting to get
out
> an approach plate, and learn to set up the approach similar to what a real
> life pilot would do. These charts aren't that difficult to read, and
after
> a while you get a real thrill from being able to go into an airport you
know
> nothing about and do an approach that would mirror what a real approach
> would look like.
>
> What you will end up doing is flying either GPS direct to an intersection
or
> VOR, then approach the ILS at the altitude and angle that the approach
plate
> says you should.
>
> 3) Don't assume that being on the ILS means you are safe. If you don't
> watch the glidescope indications, it is pretty common to underpower on the
> approach and fly below the glideslope. I can't quantify how much above
the
> glideslope you should try to be, but you shouldn't let yourself fall below
> it in IFR conditions anyway. If you get under the glideslope you can
> increase engine power to get back up.
>
> 4) Hitting the glideslope at 200 knots to land at 100 knots sounds pretty
> aggressive. What kind of airplane are you landing? I can't give you
the
> proper technique for a jet, as my landings with jets are still pure hack
> efforts (I land, but probably the passengers are calling their lawyers :).
> With Cessna Grand Caravan, I can come in around 140 knots and get
> comfortably down to under 80 knots on touchdown by extending the second
flap
> position at 2.5 knots out (measured by DME) and then bring power way down
at
> around 2 knots out. At just before the threshold I put out the third
flap
> position, go to manual approach, and do two or three gentle pullups to
slow
> down before touchdown.
>
> 5) The small planes in FS2002 have bad autopilots that won't stay on an
ILS
> in heavy winds, particularly heavy cross winds. Apparently this is true
to
> real life. These autopilots tend to overcompensate by responding to every
> displacement of the plane. Better autopilots tend to average several
> inputs together and thus compensate for outside forces like wind more
> appropriately.
>
> All of the above is HORRIBLY documented in FS2002. I had to piece this
all
> together by constantly asking annoying questions, which the members of
this
> group most graciously tolerated, and I just learned by many dozens of
failed
> approaches. Once you get the hang of it, it's generally quite reliable.
>
> My one complaint is that there is not currently a GPS controlled ILS-type
> approach mechanism because GPS is not accurate enough. I completely
> understand why GPS might not work well for a glideslope controlled
approach
> in IFR conditions. But clearly GPS *would* be plenty accurate enough for
a
> glideslope controlled approach in VFR conditions!! And this is still my
> biggest problem: I very often come into a small airfield from too high an
> altitude. Often these fields have no glideslope lights to indicate your
> position relative to the correct glideslope. This forces me to do a
"death
> dive" with two or three flaps extended, at very high airspeed. I end up
> crossing the runway threshold at far too high a speed, and if I'm not
lucky
> enough to have a long runway I have to go around. If the airfield is
> facing into a mountain or steep slope on the other side you can quickly
find
> yourself in a life or death situation. If there were a GPS-controlled
> glideslope approach you should be able to approach it from above as easily
> as from below, and once you are on that glideslope you can MUCH more
easily
> begin to control your speed during the descent, by adjusting power without
> having to worry about the trim. All these things I'm sure you learn to
> calculate for with more experience than I have. But a GPS-controlled
> glideslope approach would make it a lot easier.
>
> --
> Will
>
> NOTE: To reply, CHANGE the username to westes AT uscsw.com
>
>
>
>
> NOTE: To reply, CHANGE the username to westes AT uscsw.com
>
> "Shane H" <shs@hotmail.nospam.com> wrote in message
> news:P0Sma.6686$hF.53713@news-server.bigpond.net.au...
> > Lets say I approach the glideslope from below and hit the approach
button
> on
> > the autopilot doing 200 knots.
> > My required touchdown speed is 100 knots.
> > What controls speed along the glideslope and the required decend rate?
> >
> > The reason I'm asking is because I tried 'approach' on autopilot a
number
> of
> > times but usually the plane would loose the glideslope and I have to
turn
> > off the autopliot and land manually.
> >
> > ShaneH
> >
> >
> >
> > "donbutts" <donbutts@hotmail.com> wrote in message
> > news:59Rma.69155$jE3.1477961@news.xtra.co.nz...
> > >
> > > "newuser" <hotstuf2@gate.net> wrote in message
> > > news:b7glj9$h17$1@slb2.atl.mindspring.net...
> > > > Can it land a plane safely if something wrong happens during flight?
> > > > thanks
> > > > barry
> > > >
> > > >
> > > > ---
> > > > Outgoing mail is certified Virus Free.
> > > > Checked by AVG anti-virus system (http://www.grisoft.com).
> > > > Version: 6.0.471 / Virus Database: 269 - Release Date: 4/10/2003
> > > >
> > > Instrument Landing system is a frequency beamed from the airport at a
> > narrow
> > > angle which you have to find and position yourself for. When you are
> > > roughly on runway course and little below the required glide slope the
> > auto
> > > pilot plus the 'approach' switch will catch the course and the glide
> slope
> > > to bring the aircraft down automatically to the runway threshhold.
From
> > > there on its normally manual.
> > > Don
> > >
> > >
> >
> >
>
>
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