INSTRUMENT LANDING SYSTEM
What is an Instrument Landing System Approach?
Instrument landing system approaches are flown by pilots normally conducted in adverse weather conditions including fog as well as heavy cloud. The ILS approach is done with the use of radio signals transmitted from the airport. The signal is transmitted both in a vertical and horizontal beam like a cross in the sky.
If you imagine a light pointing up from the runway at the standard 3-degree approach angle and the torch has a piece of cardboard covering the light with a vertical crosscut into it. When you are on glide slope and lined up you can see the perfect cross. If you move to the right or left the vertical cross disappears slowly. With the transmitted ILS beam this is a little different in that the aircraft instrument can measure how far from the desired path it is.
The path is displayed on the aircraft ILS/VOR receiver which is a round dial with a movable compass ring to select the heading you require as well as two needles that deflect with the signal both horizontally and vertically. When they are centered in the display you would be lined up and on glide path for the desired runway. Its also worth noting the closer to the signal it becomes more sensitive so keep this in mind. If your 10 miles out, then you can make larger corrections, but this reduces significantly as you get close to the airport so small adjustments can have bigger effects on the guidance.
How to fly ILS approach
How do we fly and instrument landing system (ILS) approach? What basic information do we need and how can we get it for our simulator flying.
What we need to know:
- The AIRPORT we intend to land at.
- The RUNWAY we intend to land on.
- The magnetic heading of the desired RUNWAY.
- The ALTITUDE above sea level of the RUNWAY
- The current AIR PRESSURE setting for the altimeter.
- Crucial decision heights When can you land or when you must abort the landing.
Landing Notes and Charts
1. The Airport we are landing at is the first and most obvious answer and ensure you have the correct information for that airport. There has been reports of aircraft landing at the incorrect airport when there are several airports in the general area.
Check Desired Runway Correct
2. The desired runway we are going to use EG R23 Left/Centre/Right. The R23 tells us it is general heading is 230 degrees.
Magnetic Heading
3. We need to know the CURRENT magnetic heading of the runway as the earths magnetic field changes so the runways magnetic heading could be 227degrees or maybe 234 degrees so its important to check. You don’t want to land on the taxiway or be heading in at an angle to the runway. A few degrees can make a bit of a difference when you arrive popping out of the cloud to find the runway is angled and not straight in front of you.
Runway Height AMSL Check
4. The Runway altitude is very important so we know how high above mean sea level or AMSL the runway is. This will change your expected point and decision heights on whether you can continue or must abort the landing.
Check Air Pressure Setting
5. The current air pressure setting must be put into the altimeter to ensure it is working correctly and displaying the correct height. This air pressure changes rapidly on occasions and may vary by a few feet to hundreds of feet. It must be correct and the tower will give you the current altimeter setting as your getting ready to make your ILS approach.
Know Your Decision Height
6. Decision heights are the predetermined point or altitude that you must decide to continue the landing as you can see the runway or abort because you cannot see the runway at all. This height varies depending on many factors but its most commonly on the airport approach plate. This is the place where all your approach is mapped out and most of the crucial information is listed. That is the information that does not vary and they are updated normally 6 monthly.
ILS Approach Plate
- The instrument landing system (ILS) approach plate has all the information you need including ILS frequencies for each runway as well as runway elevation, current magnetic headings, decision heights and approach procedures and abort as well as holding pattern information if needed.
- Your likely thinking “Where do I get this information from for my Sim?”. There are a number of places you can get the information but one good free place is SKYVECTOR.com This is a FREE resource to get airport information all around the world. It has all the airport information you need at your fingertips. It is easy to find and easy to use. There is Approach plates and maps as well as all the general info.
Its time to set up and fly an approach. Come with me and We will fly an approach to an airport.
Click on the books to lean more about flying.
Author
