Earth-Sun Relationships, Rotation & Shape

Earth and Sun Relationships

• An observer north of the ecliptic plane will see the Earth moving in an elliptical orbit with a counterclockwise rotational direction
• The approximate distance between Earth and the Sun is 150,000,000 km
• The angle between Earth's polar axis and the ecliptic plane is approximately 66.5°
• Seasons are due to the inclination of Earth's polar axis to the ecliptic plane
• Earth's rotational axis intersects the surface at the geographic North and South Poles

Earth's Rotation and Shape

• For an observer on the North Pole, Earth rotates counterclockwise
• Earth's polar axis runs through the geographic North and South Poles, perpendicular to the equator's plane
• An ellipsoid a sphere is the best geometric form to describe Earth's shape for navigation systems

Lines on Earth

• A rhumb line cuts each meridian at a consistent angle
• A small circle is an arc that doesn't have the Earth's center as its center
• A great circle provides the shortest distance between two points on Earth
• The Earth's circumference at the Equator is about 40,000 km
• The radius of the Earth at the equator is approximately 6400 km
• The Arctic Circle, 20° S parallel of latitude, and Antarctic Circle are all small circles
• The Equator is a parallel of latitude

Distances and Coordinates

• The distance from Hanover (52°28'N, 009°59'E) to Hamburg (53°38'N, 009°59'E) on a northerly heading is 70 NM
• Flying from Hanover (52°28′N, 009°59'E) to Kiel (54°23′N, 009°59′E) on a northerly heading is 115 NM
• The longitudinal difference between 12°53'30"N and 07°34'30"S is 20°28'00"
• Polar circles are located 23.5° north and south of the equator
• The region that is divided by the polar circle is Polar and Temperate
• Distance between parallels of latitude 48°N and 49°N equals 60 NM
• The great circle distance spanning one degree of latitude equals 60 NM
• A location 240 NM north of 47°50'27"N is 51°50'27'N
• The distance between Klagenfurt (46°40′N, 014°20′E) to Linz (48°15′N, 014°20′E) is 95 NM
• The distance between two parallels of longitude 150°E and 151°E on the equator is 111 km

Rhumb Lines

• For points A and B on the same parallel of latitude, not on the equator, separated by 010°E and 020°E,the rhumb line distance between them is less than 600 NM
• The rhumb line distance between two points A and B both located on 60°N with point A at 020°W and point B on 010°W equals 300 NM
• The rhumb line distance from 60°N 040°W to 60°N 000°W on the Greenwich meridian is 1200 NM

Time and Celestial Events

• It takes the sun 0:40 h to move 10° of longitude
• 1600 Central European Summer Time (CEST) is equivalent to 1400 UTC
• UTC is an obligatory time used in aviation
• In Vienna, sunrise and sunset occur approximately 14 minutes earlier than in Salzburg
• Sunrise marks when the upper edge of the sun disk becomes visible
• Sunset occurs when the upper edge of the sun disk disappears below the horizon
• Civil twilight is the period when the sun's midpoint is 6 degrees or less below the true horizon

Conversions and Formulas

• True Heading = True Course + Wind Correction Angle
• Deviation is added to compass heading to get magnetic heading according to the formula MH = CH + DEV
• Magnetic course (MC) is calculated by subtracting variation (VAR) from true course (TC), as in MC = TC - VAR
• The value on a compass card for south-southeast is 157.5°
• The angle between the true course and true heading is called WCA, or Wind Correction Angle
• Magnetic course refers to the angle between magnetic north and an arbitrary direction
• The term "true course" denotes the measurement for any direction on Earth in reference to true north (TN)
• Its value depends, among others, on the location

Units and Charts

• Nautical miles (NM) and kilometers (km) are the official basic units for distances in aeronautical navigation
• 1000 ft is the same as 300 m
• 5500 metres are approximately 18000 feet
• Approximately, 5.5 NM is 10 km
• A reason to change runway indicators at aerodromes could be due to the changing magnetic variation of the runway location
• Direct reading compasses are influenced by electronic devices on board
• Mercator charts have a convergency of approximately 0°, are conformal, and represent rhumb lines as straight lines
• In a conformal projection chart, the scale at any point is independent of direction, and longitudes and latitudes intersect at 90°
• On a direct Mercator chart, rhumb lines are straight and great circles are depicted as curved lines
• The chart is conformal and nearly true to scale
• The lines used to determine the aircraft's position are True bearings (QTE)
• For a distance of 220 NM measured as 40.744 cm, the chart scale is 1:1000000
• 7.5 cm on an aeronautical chart equaling 60.745 NM in reality has a scale of is 1:1500000

Navigation Equipment.

• VOR/DME is the navigation aid that are used in aircraft navigation
• The DME is used to derive the distance to/from your location
• Aircraft are equipped with artificial horizon, turn coordinator, direct reading compass, airspeed indicator etc

Corrections and Speeds.

• For a short flight with a true course of 245° and magnetic variation of 7° W, the magnetic course (MC) equals 252
• An aircraft with an indicated airspeed of 150 kt at 8000 ft MSL has a true airspeed as which is 174 kt
• In scenarios involving aircraft, courses, distances, and wind components, navigational calculations are essential for determining estimated times of arrival, ground speeds, and headings
• The village Pregarten is located at a distance of 19 NM on radial 065 of the LNZ VOR/DME
• A climb rate of 900 feet per minute equates to 4.5 meters per second
• Anaircraft with calibrated airspeed (CAS): 155 kt with, Flight level (FL) 80 and Outside air temperature (OAT): -15° С the true airspeed (TAS) equals 164 kts

VDF

• One will need a VHF radio to use a VHF direction finder (VDF)
• the point in time when a VDF is 138° and the Variation is 10° E , the QUJ equals 148°
• The reading of the northern direction on the magnetic compass on board of the aircraft is called "Compass North"
• The term 'civil twilight' means a period of time from about 30 minutes before sunrise until sunrise.

Aeronautical radio transceivers

• Aeronautical radio transceivers use radio waves within the VHF range

Isogonal lines on aeronautical charts

• The Term "Isogonal" is used to denote those lines on aeronautical charts which possess the same value with respect to

Isogonic line

• A line on Earth, that connects all points on the earth
• Ground equipment for surveillance radar contains instantaneous information of distance and direction

Transponder codes

• In case of a radio communication failure, the transponder code is set to 7600
• With the transponder mode to C altitude is transmitted
• For better performance one needs a a global positioning system "GPS"

Navigation during flight

• While in flight NAVSTAR/GPS will be able to calculate from 24 different variables, making navigation easier