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Navigational Systems.

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Presentation on theme: "Navigational Systems."— Presentation transcript:

1 Navigational Systems

2 Introduction Objectives of navigation: Know your position
Efficient use of fuel Maintain a flight schedule Avoid other air traffic Avoid ground-to-air missiles and anti-aircraft artillery (known sites) Minimize exposure to enemy radar

3 Air Navigation The basic principles of air navigation are identical to general navigation, which includes the process of planning, recording, and controlling the movement of a craft from one place to another. Successful air navigation involves piloting an aircraft from place to place without getting lost, breaking the laws applying to aircraft, or endangering the safety of those on board or on the ground. Air navigation differs from the navigation of surface craft in several ways: Aircraft travel at relatively high speeds, leaving less time to calculate their position en route

4 The techniques used for navigation in the air will depend on whether the aircraft is flying under the visual flight rules (VFR) or the instrument flight rules (IFR). In the latter case, the pilot will navigate exclusively using instruments and radio navigation aids such as beacons, or as directed under radar control by air traffic control. In the VFR case, a pilot will largely navigate using dead reckoning combined with visual observations, with reference to appropriate maps. This may be supplemented using radio navigation aids.

5 Navigation Services By Another Name
Positioning, the ability to accurately and precisely determine one's location and orientation two dimensionally (or three dimensionally when required) referenced to a standard geodetic system (such as World Geodetic System 1984, or WGS84); Navigation, the ability to determine current and desired position (relative or absolute) and apply corrections to course, orientation, and speed to attain a desired position anywhere around the world, from sub-surface to surface and from surface to space; and Timing, the ability to acquire and maintain accurate and precise time from a standard (Coordinated Universal Time, or UTC), anywhere in the world and within user-defined timeliness parameters. Timing includes time transfer.

6 Main methods of navigation
Classic dead-reckoning using air data (speed, altitude) and magnetic (bearing) coupled with LORAN-C. Radio navigation Inertial navigation Satellite navigation Combinations of the above (integrated)

7 Principles of navigation
Basic navigation parameters: Altitude (barometric or radar) Speed in the X, Y and Z axes Indicated air speed (IAS), Mach number (M), and true air speed (TAS) Heading and track Position in latitude and longitude Way-points


9 Outline Introduction Radio navigation Inertial navigation
Satellite navigation Integrated navigation Instrument landing system In-class exercises

10 Radio navigation aids include:
VHF omnirange (VOR) Distance-measuring equipment (DME) Non-distance beacons (NDB) Tactical air navigation (TACAN) VORTAC (combined TACAN and VOR) Long range navigation (LORAN-C) NDBs typically operate in the frequency range from 190 kHz to 535kHz (although they are allocated frequencies from 190 to 1750 kHz) and transmit a carrier modulated by either 400 or 1020 Hz. NDBs can also be colocated with DME in a similar installation for the ILS as the outer marker, only in this case, they function as the inner marker. NDBs have a variety of owners, mostly governmental agencies and airport authorities. Determining distance from an NDB station To determine the distance in relation to a NDB station in nautical miles, you use this simple method: Turn the aircraft so that the station is directly off one of the wingtips. Then fly that heading while timing how long it takes to cross a specific number of NDB bearing. Use the formula: Time to station = 60 x number of minutes flown / degrees of bearing change Now use your flight computer to calculate the distance the aircraft is from the station by determining a time*speed = distance calculation with a flight computer. Common adverse effects Navigation using an ADF to track NDBs is subject to several common effects: Night effect: radio waves can be reflected back by the ionosphere can cause fluctuations 30 to 60 nautical miles (approx. 54 to 108 km) from the transmitter, especially just before sunrise and just after sunset (more common on frequencies above 350 kHz) Terrain effect: high terrain like mountains and cliffs can reflect radio waves, giving erroneous readings; magnetic deposits can also cause erroneous readings Electrical effect: electrical storms, and sometimes also electrical interference (from a ground-based source or from a source within the aircraft) can cause the ADF needle to deflect towards the electrical source Shoreline effect: low-frequency radio waves will refract or bend near a shoreline, especially if they are close to parallel to it Bank effect: when the aircraft is banked, the needle reading will be offset While pilots study these effects during initial training, trying to compensate for them in flight is very difficult; instead, pilots generally simply choose a heading that seems to average out any fluctuations.

11 Radio Navigational Aids
Navigation systems are the basis for an aircraft's ability to get from one place to another and know where it is and what course to follow. It's more than just maps. The closest thing today's automobiles come to an aviation navigation system is the "navigation center" some automobiles come with. These computers establish an automobile's position via satellite and place the position on a moving map. Intelligence programmed into the system allows the driver to navigate to destination by executing instructions provided by the system. Historically, aircraft navigated by means of a set of ground-based beacons, each broadcasting on its own frequencies. Aircraft systems could tune into the frequencies of two of these beacons and fly between them (from one beaconto the next). Knowing where the aircraft is between two of these beacons allows the aircraft to know where it is in a global sense. Since the 1980s, aircraft systems have evolved towards the use of satellite navigation.


13 Non Directional Beacon (NDB)

14 Non Directional Beacon (NDB)
Purpose It is used with direction finding equipment in the aircraft to provide bearing information of a location on the air route or of an airport. The NDB equipment is installed en-route areas as well as on the airports to provide navigational guidance to the pilot.

15 NDB: Operating Frequency:
ICAO has assigned Low and Medium Frequency band of 200– 1750 KHz for NDB operation; where as most of NDB equipments are found operating within frequency band of KHz.

16 NDB: Construction NDB consists of LF/MF Transmitter LF/MF Antenna and Monitor Transmission It radiates a non-directional pattern permitting reception from any point within service range of the facility (usually 200 NM). Station identification code in the form of two letter Morse Code is also transmitted by the NDB.

17 NDB: Airborne Indication
An airborne radio direction finding (RDF) equipment once tuned to the signal indicates bearing of the NDB transmitter with respect to aircraft heading. Bearing Indicator displays the bearing of the station relative to the nose (heading) of the aircraft. Relative Bearings the angle formed by the line drawn through the center line of the aircraft and a line drawn from the aircraft to the radio station. Magnetic Bearings the angle formed by a line drawn from aircraft to the radio station and a line drawn from the aircraft to magnetic north (Bearing to station)

18 NDB: Relative and Magnetic Bearing

19 NDB: Airborne Equipment
Airborne equipments that interacts with NDB (ground station) is called Automatic Direction Finder (A.D.F) and indicates bearing on a full 360 degree radial.

20 NDB: Airborne Equipment -Samples

21 NDB: ADF Airborne Indicators

22 VHF Omni Range (VOR)

23 VOR Purpose It is a radio aid that provides, with interaction of airborne equipment, information about azimuth, the course and TO-FROM to the pilot

24 VOR: Information AZIMUTH in VOR is a clockwise angle between magnetic north and the line connecting the VOR and the aircraft. The indication is displayed on an “Omni Bearing Indicator” in the aircraft. The COURSE is the information whether aircraft is flying to the left or right of, or exactly on the pre-selected course line. The course information is displayed on a “Flight Path Deviation Indicator”. TO-FROM indication tells the pilot whether an aircraft is approaching to or moving away from VOR stations

25 VOR

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