2021 Navigation Flashcards
What is a meridian?
Line of LONGITUDE that connect the poles (north to south lines).
Called TRUE meridians because they connect the geographic poles, NOT the magnetic poles.
What is the Prime Meridian?
Line which passes through Greenwich, England. Numbered 0°.
What is longitude?
Measured from 0° to 180° east and west of the Prime Meridian. (UP AND DOWN LINES).
How are longitudes measured?
Degrees(°), Minutes(‘), Seconds(‘’).
60 minutes in a degree and 60 seconds in a minute.
What is latitude?
Line of Latitude, which runs parallel to the equator.
What is the equator?
A great circle on the surface of the earth lying equidistant from the poles.
How is latitude measured?
From 0° to 90° north or south of the equator (equator is 0°).
Latitude is also measured in degrees(°), minutes(‘), seconds(‘’)
What is a Great Circle?
Shortest distance between 2 points on a map; constantly changing heading to achieve it.
What is a Rhumb Line?
A straight line where you can follow a heading between 2 points. This is the longer way.
What is Variation?
The difference in angle between geographical (true) poles and magnetic poles (magnetic).
What is annual change?
The change in variation due to the magnetic poles constantly changing; occurs from year to year.
What is isogonal?
Isogonic lines are lines that join areas having the same variation.
Isogonal lines or isogonic lines are not straight; they bend with the influence of magnetic fields below the earth’s surface.
What is an agonic line?
Agonic lines are lines drawn through places of zero variation.
Agonic lines are not straight; they bend with the influence of magnetic fields below the earth’s surface.
What do isogonic and agonic lines have in common?
They both are not straight & are influenced by the magnetic field of local magnetic bodies beneath the earth’s surface.
What is deviation?
The angular difference between compass heading and magnetic heading.
What is the difference between air position and ground position?
Air position is your position for the aircraft assuming no wind.
Ground position is a distance and direction equal to the speed and direction of the wind for a period of time in flight.
What is bearing?
Usually measured clockwise from true north magnetic north or any other reference point through 360 degrees.
4 basic elements of map construction:
- Areas
- Distances
- Shapes
- Bearing
ADSB!
What are Meridians on Lambert Conformal Conic Projection charts?
They are curves or straight lines converging towards the nearer pole.
On a Lambert Conformal Conic Projection chart, what do the meridian lines represent to each other?
They represent an angle, which is called convergency. It varies with latitude!
At equator, there is no convergency between meridians. Near the poles (at a higher latitude), the angle of convergency is at its highest.
How are the parallels of latitude viewed on a Lambert Conformal Conic Projection chart?
The parallels of latitude curve towards or ‘around’ the nearest pole.
Curvature is considerable on smaller charts!
When you draw a straight line on a Lambert Conformal Conic Projection map, what does it represent?
Represents a great circle line.
What is a rule of thumb regarding heading changes on a Lambert Conformal Conic Projection map?
“To make good a given track”
Change heading 2° for every 3° of longitude.
Flying east, the 2° is added. Flying west, the 2°is subtracted.
What are VNC and WAC charts projected as?
Lambert Conformal Conic Projection.
What charts utilize Lambert Conformal Conic charts?
VFR Navigation charts (VNC)
World Aeronautical Charts (WAC)
LO charts
How are meridians projected on a Mercator Projection chart?
Meridians are straight and parallel lines.
How are latitudes projected on Mercator Projection charts?
Latitudes are straight and parallel lines.
When you draw a straight line on a Mercator Projection chart, what does it represent?
Represents a rhumb line.
What is an adverse effect of Mercator Projection?
There is no constant scale of distance; areas are greatly exaggerated in high latitudes.
How can you use the longitude scale on a Mercator Projection chart?
The longitude scale should only be used for marking the longitude of a place.
NO, never use longitude scale on a Mercator Projection map for measuring distance.
LOOONG distance = NO MEASURING
How can you use the latitude scale on a Mercator Projection chart?
Can be used to measure distance.
How can the latitudes be used on a Mercator Projection chart?
Since 1 minute of latitude always equals 1 nautical mile, the latitude scale is used for measuring distance.
What is Transverse Mercator Projection? How does it work?
It is essentially a fix for distortion of distances of regions of high latitudes on Mercator Projection.
Transverse Mercator works by rotating the “cylinder” or map 90 degrees, so that a point of tangency is a meridian, versus the equator.
What is a benefit of Transverse Mercator Projection?
Accurate in depicting scale, especially on charts for relatively small areas.
In addition, you can select any meridian of longitude to be the reference point, depending on your region of flight.
What maps are based on Transverse Mercator projection?
VFR Terminal Area charts (VTA).
Smaller area, more accuracy with Transverse Mercator!
What projection is used for VTA’s?
Transverse Mercator Projection.
What is the scale of VFR Navigation Charts (VNCs)?
1:500,000; 1 inch to 8SM!
What is the scale of World Aeronautical Charts (WACs)?
1:1,000,000; 1 inch to 16SM!
What is the scale of a VFR Terminal Chart (VTA)?
1:250,000; 1 inch to 4SM!
What are hypsometric tints?
The colour-coding range from green to yellow to bronze depicting height in terrain (1,000ft increments).
What are contours?
Contour lines are lines drawn on a chart joining points of equal elevation. The closer the lines, the steeper the inclination of terrain.
What are position lines?
Are attained by observing the bearing of two or more objects that are plotted on a map or chart to fix a position.