GNav Flashcards
What are isoclines ?
Lines of constant dip
What are aclinic lines ?
Magnetic equator where lines are horizontal so there is no dip
What are agonic lines?
Lines of zero variation
What is departure formula ?
Departure = CHLong(mins) X cos(CHLat)
Departure (distance) normally in NM
What is earth convergence formula ?
Convergence = CHLong (degrees) X sin(CHLat (mean))
What is the conversion angle formula ?
0.5 X earth convergence
Then minus or add that to track direction
What is CHLat distance formula ?
Distance = CHLat X 60
What cause magnetic north to move ?
Solar wind
Sun variation
Poles move in loops, up to 45 No per day
Which month does Aphelion occur ?
July - Earth is furthest away from the sun
What is the highest latitude which the sun can be vertically overhead ?
23.5 degrees
Which months see biggest difference between apparent and mean noon ?
February and November
What time of year does earths length of daylight change the most ?
Autumn and spring
What is the mean sun ?
When a fake sun collides with the real sun at the spring equinox and travels along the celestial equator
What is celestial ?
Fictitious position relating to earths globe.
So there’s a imaginary equator, poles, sun etc
Which way does Earth orbit around the sun and on its plane ?
Anti-clockwise
What is the circumference of the earth ?
40,000km
What is the diameter of the earth ?
12730 Km
40000/Pi
What is the radius of the earth ?
6730 Km
What is the latitude which the maximum difference between geocentric and geodetic occurs ?
45 N/S
What are rhumb lines ?
They are small circles. They concave to the poles. They cut meridians at same angle. They are also half meridians, as a meridian only does a 180 of the earth and not 360 around it, which is what a great circle is, 360.
When does pherihelion occur ?
4th January.
What are Keplers laws ?
First law pherihelion and apherihelion
Second law; further away from the sun the earth is, the slower it orbits, and the closer the earth is to the sun the quicker earth orbits
When is the spring equinox ?
20/21 March
When is the autumn equinox ?
22/23 September
When is the summer solstice ?
21/22nd June
When is the winter solstice ?
21/22nd December
What is the major formula ?
(Minor/297)X298
What is the minor formula ?
Major - major/298
What are great circles ?
They convex to poles, cut meridians at different angles
What is formula for True air temperature?
Static air temperature + Ram Rise
What is the formula for Static air temperature ?
True air temperature - ram rise
Companies which contract datalink:
SITA
ARINC
Who are the satellites operated by ?
INMARSAT
