ppl_03_e2
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Customer: Oleg Ostapenko E-mail: ostapenko2002@yahoo.com
Customer: Oleg Ostapenko E-mail: ostapenko2002@yahoo.com
CHAPTER 5: AERONAUTICAL CHARTS AND CHART-MAKING
PROPERTIES OF AN IDEAL AERONAUTICAL CHART.
Although, as you have seen, the spherical surface of the Earth can never be represented on a two-dimensional chart without the Earth’s surface undergoing some deformation, a high degree of accuracy can be achieved amidst the inevitable distortions. If the ideal chart could ever be produced, its properties might be summed up as follows.
•Land masses should be represented with their true shape on the chart.
•Areas on the Earth’s surface should be shown as proportionally equal areas on the chart. If the shape and area of features on a chart are not accurate, scaled-down versions of the same areas on the Earth’s surface, then the chart may confuse the navigator.
•Angles on the Earth’s surface should be represented by the same angles on the chart.
•Scale should be constant and correct.
•Rhumb Lines should be straight lines.
•Great Circles should be straight lines.
•Latitudes and Longitudes should be easy to plot.
•Adjacent sheets should fit correctly.
•Coverage should be worldwide.
VFR Aeronautical Charts.
The two most widely used charts used in visual air navigation, in the United Kingdom, are the ICAO 1:500 000 series of charts and the UK CAA 1:250 000 series.
As we have seen, both types of chart, which, if we take individual sheets from the series, cover only relatively small areas of the Earth’s surface, achieve quite a high level of success in reproducing many of the ideal properties of an aeronautical chart.
On both charts, a straight line drawn to represent the desired track between two locations, represents a straight line on the Earth’s surface for the area covered by the chart. A straight line on a UK CAA 1:250 000 series chart is a rhumb line. On the ICAO 1:500 000 chart, a straight line represents a great circle on the Earth. However, over the area represented by each 1:500 000 sheet, there is no discernable difference between a great circle and a rhumb line.
Distances are accurate over both charts, and, in practical terms, shape and scale are conserved.
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CHAPTER 5: AERONAUTICAL CHARTS AND CHART-MAKING
CONCLUSION.
All navigation charts, then, are projections which, though the task is not perfectly achievable, attempt to conserve on a flat surface as many of the characteristics of the true surface of the Earth as possible, to a greater or lesser degree of accuracy. For a navigator, the most desirable characteristic is to conserve accuracy of direction with respect to meridians of longitude and parallels of latitude because, if their coordinates are accurate, it is relatively easy for the navigator to determine where he is on the Earth’s surface and to plot bearings and tracks to get from one place to another. If there is distortion of surface area and distance, those are disadvantages but not major ones.
Both the ICAO 1:500 000 series of charts and the UK CAA 1:250 000 series exhibit many of the properties of an ideal chart.
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ID: 3658
Customer: Oleg Ostapenko E-mail: ostapenko2002@yahoo.com
Customer: Oleg Ostapenko E-mail: ostapenko2002@yahoo.com
CHAPTER 5: AERONAUTICAL CHARTS AND CHART-MAKING QUESTIONS
Representative PPL - type questions to test your theoretical knowledge of Aeronautical Charts and Chart-Making.
1.One inch on a 1:500 000 scale map represents:
a.Approximately 10 nautical miles
b.Approximately 5 nautical miles
c.Approximately 8 nautical miles
d.Approximately 7 nautical miles
2.Three centimetres on a 1:250 000 scale chart represents:
a.Approximately 2.5 nautical miles
b.Approximately 4 nautical miles
c.Approximately 2.5 kilometres
d.Approximately 7.5 nautical miles
3.On a chart with a scale of 1:1 000 000, 20 cm represents:
a.116 nm
b.86 nm
c.40 nm
d.108 nm
4.Given a chart scale of 1:1 000 000 what is represented by a chart distance of 8 inches?
a.103 nm
b.110 nm
c.115 nm
d.153 nm
Question 1 2 3 4
Answer
The answers to these questions can be found at the end of this book.
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CHAPTER 6
FEATURES ON
AERONAUTICAL CHARTS
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CHAPTER 6: FEATURES ON AERONAUTICAL CHARTS
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CHAPTER 6: FEATURES ON AERONAUTICAL CHARTS
INTRODUCTION.
By using aeronautical charts, pilots are able to measure and mark their desired track to a destination or turning point and to determine their position along that track. Enroute navigation aids and relevant radio frequencies can be identified from the chart, as can the boundaries of controlled airspace, possible diversion airfields and other useful aeronautical information, such as terrain and obstacle elevation, essential to the safe conduct of the flight.
Figure 6.1 Aeronautical charts enable pilots to determine track and position. Aeronautical charts contain details of controlled airspace, terrain elevation and other information essential to the safe conduct of the flight.
As we have seen, the two most common aeronautical charts used by pilots for visual navigation, the ICAO 1:500 000 and UK CAA 1:250 000 charts, contain many of the characteristics required of an ideal chart. However, apart from an aeronautical chart needing to be accurate in terms of angles and distances, one other very important quality that a VFR pilot requires in an aeronautical chart is that it should clearly display all the necessary features and aeronautical information that he needs for visual navigation. The pilot must be able to read and interpret information from the chart rapidly and with ease, in order that he can pinpoint his position along track, recognise any deviation from track, and continue to conduct his flight safely without infringing controlled airspace.It is impractical that aeronautical charts should show every detail of ground features, in the way that road maps and Ordnance Survey maps
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CHAPTER 6: FEATURES ON AERONAUTICAL CHARTS
do. Aeronautical charts must contain only those features and items of information which are essential for the pilot to carry out a successful, safe navigation flight. Such information will include, for instance, high ground and obstacles, to enable the pilot to maintain safe vertical separation from the ground. Regulated airspace is also marked, so that the pilot knows where he can and cannot fly. Motorways, railway lines, large towns, and rivers are clearly shown, so that the pilot can pinpoint his position.
Figure 6.2 Aeronautical charts must contain only those features and items of information which are essential for the pilot to carry out a successful, safe navigation flight.
THE ESSENTIAL FEATURES MARKED ON AN AERONAUTICAL
CHART.
On the 1:500 000 and 1:250 000 aeronautical charts, these essential features appear in the form of symbology which, for the most part, is recognised internationally.
This symbology represents the following principal features, among others:
•topography, (terrain detail and relief, including spot heights of terrain and obstacles).
•hydrography, (water features: rivers, canals, lakes, seas and oceans).
•man-made constructions, (cities, conglomerations, towns, villages, roads, railways, obstructions, forests, and even “white horses”).
•details of controlled and uncontrolled airspace (control zones, control areas, airways, air traffic zones, danger areas, prohibited areas, restricted areas etc).
•radio navigation aids, (VOR/DME beacons, NDBs, VDF equipped airfields, TACANs etc).
Both the 1:500 000 and the 1:250 000 aeronautical charts are topographical charts. As the scale of the 1:500 000 chart is particularly suited to the speeds and altitudes flown by general aviation aircraft, on VFR cross country flights, that is the chart to which we refer primarily in this book. The particular sheet we shall be using is 2171CD, Southern England and Wales.
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CHAPTER 6: FEATURES ON AERONAUTICAL CHARTS
If it is necessary to have greater detail than that shown on the 1:500 000 chart, for instance, if a difficult-to-spot feature is needed as a fix, or if a pilot is approaching an unknown aerodrome or airfield, the 1:250 000 chart may be used.
For the study of this and subsequent chapters in the General Navigation section of this book, you should have your own up-to-date 1:500 000 aeronautical chart at hand. You should study your chart closely and regularly, and familiarise yourself with the detail of its symbology which is explained in the key or legend usually situated in the bottom left-hand corner of the chart.
You should particularly endeavour to become familiar with and recognise, as early as possible in your flying career, the following characteristics and features of the aeronautical chart that you use regularly.
•Terrain relief and elevation of terrain and obstacles.
•Spot elevations.
•Maximum Elevation Figures (MEF).
•Controlled airspace (control zones (CTR) control areas (CTA and TMA) and airways).
•Aerodrome traffic zones (ATZ).
•Prohibited areas.
•Danger areas.
•Restricted areas.
•Bird sanctuaries.
•Military low flying areas.
•Areas of intense aerial activity.
•Radio navigation facilities (VOR/DME beacons, NDBs, TACANs etc).
•Magnetic information (isogonals).
•Sites of other aerial activities (microlights, gliding, ballooning, parachuting, etc.).
Terrain and obstacle elevation, knowledge of which is essential to a pilot in order that he may calculate and maintain a safety height, is covered in a little more detail, later in this chapter, as is regulated and controlled airspace. Magnetic information has been dealt with in Chapter 3.
Radio-Navigation Aids on the 1:500 000 Chart.
Radio navigation is covered in the second part of this book. Learn the symbology for radio-navigational aids well (See Figure 6.3 overleaf). In the navigation skills test, after the first leg has been flown, you may be asked to confirm your position by
In the
navigation skills test,
after the
first leg has been flown, you may be asked to confirm your position by reference to radio-navigation aids, and could be tasked by
the examiner with basic radio-navigation tracking.
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CHAPTER 6: FEATURES ON AERONAUTICAL CHARTS
Figure 6.3 Radio-navigation aids shown on a 1:500 000 aeronautical chart.
reference to radio-navigation aids, and could be tasked by the examiner with basic radio-navigation tracking. Seek your flying instructor’s advice on these tests and procedures.
Figure 6.3 includes details of several radio-navigation aids. Consult your own chart, in order to examine the detail. This section of the 1:500 000 chart includes the Daventry VOR/DME with its compass rose orientated on magnetic north and its VHF frequency of 116.4 MHz; this VOR/DME, as you see, is not situated at an aerodrome, though many are, but serves as a beacon for IFR traffic in the Daventry Control Area. There is also the NDB at Oxford Kidlington with its frequency of 367.5 kHz, and the Terminal DME on 108.35 MHz.
The converging line symbol to the North of Oxford Kidlington, containing a series of “chevrons” pointing towards the aerodrome, indicates that there is an instrument approach procedure at Oxford Kidlington. This symbol is attached to aerodromes outside regulated airspace which have one or more instrument approach procedures. It is strongly recommended that pilots contact the aerodrome’s Air Traffic Services Unit if flying within a radius of 10 nautical miles of such an aerodrome.
The Oxford Kidlington NDB is not indicated by the standard NDB symbology of concentric broken circles; but standard symbology does indicate the NDB, BZ386 (386 kHz is its frequency) at Royal Air Force Brize Norton. RAF Brize Norton also has a military radio-navigation aid called TACAN (TACtical Air Navigation). The DME
facility of the TACAN is also useable by civilian traffic.
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