Navigation Flashcards
What is the general definition of air navigation?
The process or method with which an ACFT is guided safely from its starting to point to its destination. This involves determining the position of the ACFT, monitoring its flight path and making any necessary corrections.
What are the 5 main components of navigation?
Position, Course, Distance, Time and Altitude
What are the 4 methods of air navigation?
- Visual navigation
- Dead reckoning navigation
- Radio navigation
- Area navigation which includes inertial navigation, VOR/DME, DME/DME, Satellite navigation and LORAN C
Approximately how many kilometres does the Diameter of the earth differ from pole to pole to measuring at the equator?
42km
What is the mean circumference of the earth in km and NM?
- 40000 km
- 21600 NM
What is the rotational speed at the equator?
1670km/hr (900kts) - 15 degrees per hour
What is a great circle?
- A circle on the Earth which lies in a plane that passes through the centre of the Earth.
- Route along great circle represents shortest distance on the Earth between 2 points.
- Examples include the equator and all circles of longitude.
What is a Meridian?
- Line of Longitude (great semi-circle) joining the North and South poles.
- Prime Meridian passes through Greenwich - used worldwide since 1884.
What is a small circle?
A circle on the Earth which is not a great circle such as Parallels/Circles of Latitude (Parallel to the Equator)
What is the tilt of the earths axis?
23.5°
What is the Tropic of Cancer?
Parallel of latitude approximately 23.5° North and is the northernmost latitude reached overhead by the sun.
What is the Tropic of Capricorn?
Parallel of latitude approximately 23.5° South and is the southernmost latitude reached overhead by the sun.
Define ecliptic
The name of the plane on which the Earth moves during its orbit around the Sun.
What is a sidereal year?
The orbital period of the earth around the sun, taking the stars as a reference frame. It is 20 minutes longer than the tropical year because of precession.
What is a tropical year?
365.25 days
What is a gregorian year?
A year of mean length which results from normal years and leap years (365.2425 days)
When does a day start?
Starts at the lower culmination of the sun. At midday, the sun reaches the upper culmination.
What is a true solar day?
2 successive lower culminations of the sun
What is a mean solar day?
2 successive lower culminations of the mean sun. Its length is constant and equal to the mean length of all true solar days.
What is Local Mean Time (LMT)?
The time at the meridian of the point in question dependent on the geographical longitude only.
What is Zone Time (ZT)?
Division in zones with 15° longitude. The centre meridian defines zone time.
What is Standard Time (ST)/Legal Time (LT)?
Based on the zone time and fulfils legal, political and economic interests.
What is Universal Time Coordinated (UTC)?
Based on international atomic time, kept within 0.9s of UT1 and is closely related to GMT. This is the time used in air navigation all over the world.
What do the actual times of sunrise (SR) and sunset (SS) depend on and where can they be found?
Season and geographical latitude. Times can be found in the AIP.
What is civil twilight?
Begins or ends when the centre of the sun lies 6 degrees below the horizon. The average length is about 40 minutes at 50° latitude.
Why is a magnetic grid not possible
Due to disturbances in many areas and the magnetic north and south poles are not directly opposite.
What is magnetic variation?
The angle between the magnetic meridian and true meridian.
What are isogonic lines?
Lines on a chart which indicate the magnetic variation in a particular area.
What is deviation?
Angles between compass north and magnetic north.
What are the types of map projections?
Conical, cylindrical (Mercator) and azimuthal
What are the properties of lamberts conical projection? (8)
- Meridians - straight lines converging towards the poles.
- Parallels - concentric arcs of circles.
- Great circles - approximately a straight line.
- Rhumb lines - curve towards the equator
- True Scale - sufficient for practical purposes
- True angles - yes
- Distortion - slight
- Use - all types of navigation at medium latitudes
What scale of chart is used for aeronautical charts?
1:500,000
What are the 3 types of vector in the wind triangle?
- Air vector - single red arrow (Shows heading and TAS)
- Ground vector - double green arrow (Shows track and GS)
- Wind vector - triple blue arrow (Shows wind direction and speed)
What types of speed are used in air navigation? (7)
IAS, CAS, EAS, TAS, Wind speed, GS and Mach number
What do ATC use IAS for?
Applying speed control
What is mach number and when is it applied?
The ratio of TAS to the local speed of sound. Its used for speed control above FL245
What is the difference between upper wind and surface wind with regards to direction?
Upper wind direction is given in degrees true.
Surface wind is given in degree magnetic.
What is the drift angle (DA)?
Angle between heading and track.