Oxford, Air Navigation
Oxford - Time: DGCA Air Navigation questions
Navigation time is measured from the Sun and the stars. The tilt of the Earth's axis as it orbits sets the seasons, the solstices and the Sun's declination, and local mean time, zone time and twilight follow from that geometry.
Most of the 28 questions are astronomy: perihelion and aphelion, equinoxes, the ecliptic, sidereal against solar time and the equation of time. Others convert arc to time, use hour angle and read twilight tables. DGCA exam sessions have drawn on 4 of them.
One minute of arc is four seconds of time, not four minutes. East of Greenwich, local mean time is ahead of UTC. Hour angle runs westward through 360 degrees, while longitude runs 180 each way.
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Question 1 of 5
When does perihelion occur?
Question 2 of 5
When does aphelion occur?
Question 3 of 5
Viewed from the North Celestial Pole above the North Pole, the Earth orbits the Sun:
Question 4 of 5
When do the equinoxes occur?
Question 5 of 5
When it is the Winter Solstice in the Southern hemisphere, the Declination of the Sun is:
23 more questions in this chapter
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