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The ILS, or Instrument Landing System is what we can use to make a precision instrument landing on
the runway of our choice.. Not all airports, and not all runways at airports are equipped with ILS. Look under help in 'airport facilities' for more information on the airports and runways
available as a default in FS. An ILS system consists of 2 main transmitters. The Localizer and the glide slope. The localizer
is usually located at the far end of the runway. While a VOR signal radiates 360 degrees., a localizer signal is much narrower and can usually only be picked up within about 20
miles of the runway, and then again only if you're flying within about 35 degrees of the approach heading. The localizer frequency or ILS
frequency is indicated in the flight manual next to the runway numbers. Chicago O'Hare runway 27R is 110.5.. As you near your final approach, this is the frequency you would put into your NAV 1
radio. In many cases you will also see a DME number appear. DME
stands for distance measuring equipment. This will tell you roughly how many Nautical miles you are from the transmitter. Remember, localizers are usually at the end of the runway, so if you're 5 miles out and the runway is 10,000 feet long, you're really only about 3 miles from landing. Not all
ILS and VOR have DME equipment. Many do, some don't. You will use the OBI (Omni Bearing Indicator) gauge marked V1
on the cessna to make your final approach. The glide, slope, and localizer are built into the same gauge. If you look at the gauge you will see a circle in the center, and 2 'needles'. The horizontal needle indicates your position in relation to the glide slope. The glide slope is what determines the altitude your plane should be flying on approach. The needle tells you where you should be, not where you are. If the horizontal needle is above the center circle, the plane should be higher. If the needle is below the center circle, the plane should be lower. The vertical needle shows your relationship to the
localizer
and the runway. It tells you if you are lined up with the runway. Again, it tells you where you should be, not where you are. If on final approach, the needle is off to the left, you should turn slightly to the left till you intercept the glide slope. One thing you can do to make things easier is to put the actual heading of the runway in the top number on
OBI gauge V1. You will find that if both needles are centered, your heading will be about the same as the number you have entered for the runway heading. You should try to
intercept the glide slope initially at no more than a 45 degree angle. In other words, if the runway heading is 270, you should try to intercept the glide slope and localizer
at no more than 225 degrees or 315 degrees., depending on which direction you are approaching from. If you intercept the glide slope
at more than a 45 degree angle, chances are, by the time you have finished your turn, you will have passed the glide slope and will have to turn again to intercept the glide slope
. For beginners it's a good idea to try and line up your approach starting about 10 miles out. This gives you plenty of time for corrections. Try using lesson 1 to practice your ILS
approaches. In that lesson, you are actually intercepting the glide slope at a 90 degree angle. And more than 10 miles out. If you let the autopilot lock on the glide slope
(Control -OH), you will see it make numerous turns back and forth across the glide slope to line up with the runway. In reality a pilot would begin his turn earlier so as to intercept the glide slope
at a better angle and closer to his actual final approach. It's fairly simple to use the ILS
in flight simulator. If you don't get it your first time, keep trying. Once you understand the basic concept, it will seem pretty easy. |
