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The VOR Part1
VOR stands for Very High Frequency Omni directional Radio range The VOR radio beacons do not suffer distortion like the NDB They work on line of sight and have a range of up to 200 miles depending on the height of the aircraft and terrain There are various types of VOR but all do the same job The VOR can be used for on route navigation OR Holding Patterns or Runways approaches in bad weather An airway is 10 miles wide and can be used by pilots flying along a route for example routing VOR to VOR IE VOR in Abbeville on the French Coast to Biggin Hill in South London then Manchester and Glasgow Radio Beacons tend to be named after places they are near or at. They have 3 letter identities ABB = Abbeville BIG = Biggin MCT= Manchester for example. They transmit on frequencies between 108 and 117.75 at 25 mhz seperation. On beacons used for approach they often have the weather and airfield information being voice transmitted .This is updated at regular half hour intervals. This is on a loop so it goes on repeating itself. This is a good .It saves upsetting the approach controller when30 aircraft are all flying towards each other and someone asks for the detailed weather. Imagine Heathrow Approach not having this . Each VOR transmits its 3 letter identity in Morse code for the pilot to identify it as the correct beacon. From Air Charts the pilot can plan his route using VORs and NDBs so that if the sky was obscured by cloud he could navigate with accuracy, without being able to see the ground. Some VORs have distance measuring equipment DME the pilot can also then tell what heading the beacon is and how far the VOR is from him and then can plot it on the chart. Aircraft Equipment This Consists of a radio transmitter and receiver, The aircraft equipment receives the signal from the VOR. The equipment can tell which radial the pilot is on, and if it is a VOR/DME it will tell the equipment the distance as well. The aircraft instrument has a needle that moves left to right and back across the dial. The idea is you keep the needle in the centre and you are on course . The instrument also has little flags that show TO or From or blanked out with a warning flag if the signal from the VOR is not received. There is also a knob called OBS or on airliners is often shown as course. Once the pilot has tuned and identified the VOR, all he has to do now to fly to the VOR is turn the OBS knob until the needle centres with a TO flag showing. Above the instrument is a readout of numbers that moves as you turn the knob .Once you have got the needle centred ,read out the figure on the top and that is the heading you have to fly to reach the VOR.. For this lecture we are using the bottom left VOR instrument In the picture below the heading to the VOR is 340 on the bottom VOR instrument. the radila is 340-180 =160 shown in the 6 o clock position
You will notice on the instrument that there are dots either side of the VOR centre dot. These represent 2 degrees. So if the needle was to the right one dot the pilot would alter his aircraft 4 degrees to the right to regain track once the needle centres the pilot will turn left 4 degrees back on to the original heading (see below) (note this is double the track error.) it is either caused by not flying an accurate heading or wind drift which you may now have to compensate for.
THE NEEDLE WILL DISTORT AS YOU FLY OVERHEAD THE VOR. IGNORE IT YOU WILL SEE THE FLAG GO FROM TO, TO FROM VERY QUICKLY. IF IT DOES THIS YOU ARE READY FOR THE NEXT STAGE OF THE TRAINING. the barbers pole needle is shown when directly above the VOR or when not receiving a signal.. The closer to do VOR the more it distorts. Remember, to regain track you always turn and fly towards the direction of the needle from the centre of the instrument.
On jets the VOR is shown in different format to that of a light aircraft. It shows the course as well as the needle.
A further lecture will follow on how to fly a set course using the VOR. for now Just practice tuning a VOR and flying to it and then retune another VOR overhead this VOR . To find a VOR frequency in flight Sim 2000 bring up the map window and click on the VOR a window will open telling you the frequency. Once you can do that we are well on our way to teaching you the tricks of approaching to land in cloud using a VOR or flying an airway.
Part 2
Flying A Set Track to a VOR or Intersection or Approaching to Land Using A VOR
Let us now suppose we are taking off from London Gatwick and we are going to do a Standard Instrument Departure to Dover where we are going to use the Airways to Fly to Belgium. All we are concerned with in this lecture is how to use the navigation equipment not the rest which you can learn later. The Dover Standard departure from runway 26 Left requires that we take off and turn right and fly to an intersection called Acorn. Acorn is on the Detling 262 Radial at 23 DME (nautical Miles From Detling) It is also on the Dover 281 Radial a distance of 44 miles from Dover. On our aircraft we have two VOR instruments we set the first one up tuned to Detling and the second one up tuned to Dover. See the Diagram of the route. The first course to Acorn requires a hadeing of 82 degrees not corrected for wind. We therefore tune in the frequencies and set the OBS to 082 IE 262-180 The VOR will not normally work on the ground due to line of site. On Take off the needle will activate and the TO flag should show the needle will be over to the left of the instrument telling us to fly to the left. to intercept the track. the track is 82 so we need to fly at about 45 degrees less than the track so as we intercept it. As we start to intercept it the needle will start to move to the centre. At this point turn onto a heading of 82 degrees and keep the needle centred making slight adjustments on the heading to get the needle centred. if you have 2 needle type instruments the second OBS should be set to 101 which is the inbound track to Dover. As the aircraft approaches Acorn the VOR 2 needle will start to swing in to the centre when both needles in in the centre of their gauges you have reached ACORN .You can also check your DME It is 15 from Detling and 44 From Dover. All you need to do now is turn heading 101 to Dover. At Dover you set the new course to Koksy in Belgium by adjusting the OBS needle to 99. Tune up the KOKSY VOR 114.5 set 99 on the OBS .The course you need to fly to Koksy then alter heading to keep the needle centred. If the needle is to the right you fly right if it is to the left you fly left. One dot is 2 degrees. so to correct double the deviation.and that is all there is to flying the VOR and Airways. You can see that if a runway is on a set course from a VOR you can land using it. It just means you have to intercept a radial to fly on to the runway. Between Dover and Koksy rely on the Dover VOR until half way then rely on the Koksy VOR. You can set the Dover VOR OBS to 99 now you will see the needle work the same but the the flag has gone to From.
This picture shows the scene just after take off from Gatwick. As you line up on Gatwick Runway 26 the Detling 262 radial was off to our right. On take off we have turned right and are heading to intercept this radial Note the RMI to the left is telling us the heading to Detling as well as the radial so we can keep track of them and know when to turn. You can see the radial is running right to left in front of the aircraft indicated by the first green line with the DET 01 mark on. Now look at the right hand picture the course indicator is telling us the same. The magenta moving bar is telling us we are about one degree off the radial we require. This bar would have started off being right up the top of the gauge, as the aircraft came within ten degrees of the set radial it would start moving down. The aircraft at the time of this photo was in a 25 degree bank turn to the right. and has intercepted the 262 Detling radial. The closer to the VOR the quicker the needle moves down.
We are now tracking towards Detling on the 262 radial we have a crosswind from the left and we are now being told we are one degree off course from the required radial the aircraft is right of track The pilot would change heading a few degrees to correct it to get the needle back in the centre. When the needle is in the centre you are on course remember. The other way of checking is the RMI is at 12 O Clock with the required radial in it. Notice also the to flag in front of the aircraft in the centre of the dial.
The above picture shows the Acorn Intersection. Note the radial from Detling and the radial coming in from Dover from the One O clock position. Where the lines cross is the intersection. Airways are made up of intersections and NDB or VOR Beacons. The intersections are also known as reporting points. Intersections are shown as a little triangle . If it is blacked in the pilot should report over it to ATC. If it is not it only has to be reported if ATC request. Intersections can be a set distance from a beacon on a radial or where two radials cross like here. The aircraft has started to turn towards Dover the second VOR we are using for our flight. The course OBS has been set to 101 and the Dover Beacon tuned in now on VOR Box One. We keep repeating the process all the way down the route now flying radials to and from beacons and intersections using charts to assist us. More on VOR flying is in the Airliners Course. That is all there is to VOR flying practice this.it is one of your bread and butter subjects. The ILS works similar principle which is the next lesson the dots on the gauge represent 1 degree then instead of two degrees deviation.
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