![]() ![]() It's a bit of a guess on how much that compensation should be. The heading bug should be set over the bearing of the NDB towards the wind direction so to compensate for the wind. Bringing the heading bug back each time the aircraft will have flown a long wide curve instead of a straight line. The wind will blow the aircraft off course and the bearing of the NDB will drift slowly over the compass rose. Setting the heading bug on the bearing of the NDB once will not bring the aircraft over the radio station.A VOR radial will bring the aircraft with high accuracy in a straight line over the radio station.With a NDB we set the heading bug, with a VOR we select the radial. For position finding we need to know what radio stations can be near so we can test the frequencies of the stations.Īircraft deviating from course by wind towards a NDB station.Īs soon as we pick up a signal from a radio beacon we can easy navigate towards it. On-board we begin with a known frequency and then tune in. At home we turn a knob or press a button and the radio receiver finds the first station. The bearing of NDB stations can be inaccurate, it is advised to use at least three NDB bearings for position finding.įrequency selection on the radio receivers on-board differ from the radio receiver we have at home. On the map we draw the two radials from the stations to find our position at the cross point. With two NDB stations we have two bearings on the compass. With two VOR stations we receive two radials.From that we use the map, a compass rose and a ruler to pinpoint the position. It gives the radial we are crossing and the distance to the station. We need tune in to just one VOR-DME to pinpoint our position.(in FlightGear the identity can be found in the property tree at /instrumentation/nav/nav-id) That identity gives a good clue where we are on the map but we have to pinpoint our position before we can navigate any further. Lucky most radio beacons tell their identity, in Morse code or in other ways. Going further on the way it is possible to get lost so it is important to figure out where we are if we get lost. We always start from an airport, we know where it is on the map. Position finding with NDB, VOR and VOR-DME For long tracks without radio beacons nearby (and no GPS) it is the only way to navigate. Even with the navigational tools that are available today we rely on this method without knowing it. If there is a good compass and the ground speed is known it is even possible to do some navigation with this method. If you know where you are and how fast you move you can predict where you will be after some time. ![]() Always check if the VOR provides a radial before using it for automated flight.ĭead reckoning ( DR) is a technique we use every day in many situations. ![]() Sometimes a VOR station does not operate as expected and will behave as a NDB.Always be sure to know the identity of a station before using it. The strongest signal is not always the nearest. Our equipment will tune into the signal that is strongest. Often there are radio beacons near each other that transmit on the same frequency.For approach and landing there is no replacement for radio beacons. ![]() If the GPS fails the course is back on radio beacons. Satellite navigation (GPS) is taking over parts of radio navigation but each pilot will base their primary course on radio beacons and then use the GPS. With a non-directional beacon ( NDB) station we use the heading bug, with a VHF omni-directional range ( VOR) station we select the radial to use and the autopilot keeps us on that course. Our aircraft have an autopilot and radio beacons are ideal for automated flight. The time that a pilot had to fly with the yoke in their hands all the time has long been passed. Radio beacons are placed near airports, can be aligned with runways and can be placed in remote areas so to mark a route over them. The position of radio beacons is clearly marked on navigation maps. Radio beacons can be seen with the right equipment, from far away and independent of the weather. Instead of relying on visual landmarks (such as roads, rivers, churches, and towns) for navigation under visual flight rules ( VFR), radio navigation relies on radio beacons and is therefore a critical part of instrument flight rules ( IFR). ![]()
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