General / Misc Nav stuff (NAV) Flashcards
What is the ICAO definition of navigation?
The process or method with which an aircraft is guided safely from its starting point to its destination, including determining the position of the aircraft, monitoring its flightpath and making any necessary corrections.
What are the 5 main components of navigation?
Position Course Time Altitude Distance
What is the standard scale of a VFR chart?
1:500,000
How flattened is the earth?
About 1/300
What is the mean circumference of the earth?
40,000km (21,600NM)
What is the mean radius of the earth?
6367km (3438NM)
What is the mean diameter of the earth?
12,735km (6876NM)
What is the rotational speed of the equator?
1670km/h (900kt) 15degrees/hour
What is the definition of a Nautical Mile?
The distance of any segment of any path describing a great circle of the earth which is intercepted by 1 arc minute measured from the centre of the earth.
How far is the Earth’s axis of rotation tilted? Where does this mean the tropics are?
23.5 degrees, making the tropics 66.5 degrees north and south of the equator.
How far does the Earth rotate in an hour? In 4 minutes?
15 degrees and 1 degree, respectively.
What is a geoid?
An equipotential surface (a surface across which gravity is the same) equal to mean sea level.
What is an ellipsoid, and what is the standard reference ellipsoid for aviation?
A mathematical model of a near-sphere, intended to be similar to the dimensions of the Earth. WGS 84 is the standard reference.
What is the name of the plane on which the Earth orbits the Sun?
The elliptical plane.
What are the two astronomical definitions of the year? Which is used in aviation?
The Siderial Year, which is the amount of time it takes an arbitrarily-distant star to return to the same position in the sky, and the Tropical Year, the amount of time it takes the Earth’s rotational axis to return to the same place relative to its orbital axis. The tropical year is the one we care about.
What is a “true solar day”?
The time between two successive lower culminations of the sun.
What is the single-letter code given for UTC?
Z.
What is the aeronautical definition of twilight?
The time during which the Sun is 6 degrees below the horizon.
What is the process of flying by following a steady compass heading called?
Following a Rhumb Line.
What is the term for the difference between true north and magnetic north?
Magnetic declination, also called magnetic variation, measured in degrees east or west.
What are Agonic and Isogonic lines?
Agonic lines are lines along which the magnetic declination is 0. Isogonic lines are lines along which magnetic declination is constant.
What are local magnetic disturbances called? How can the arise?
Magnetic deviation, which can be caused by large pieces of ferromagnetic metals, or circuitry, or large amounts of radiation.
What is the difference between compass north and magnetic north?
Compass north is where your compass happens to be pointing right now. Magnetic north is where your compass should point if you weren’t experiencing a bunch of magnetic deviation.
What are the three vectors in dead reckoning navigation, and what are they made up of?
Air vector is your true airspeed and your heading. The wind vector is the wind speed and direction. The ground vector is your track and resulting actual speed.
What are the steps and corrections between indicated air speed and true air speed?
Indicated air speed, corrected for mechanical shortcomings in the equipment according to the pilot handbook for that plane (instrument error) is the calibrated air speed.
Calibrated air speed, corrected for the compressibility of air, is the equivalent air speed.
Equivalent air speed, corrected for air pressure, is the true air speed.
What are the drift angle and wind correction angle?
The drift angle is the amount the wind causes your track to deviate your heading. The negative of this is the wind correction angle: the amount one should adjust their heading in order to fly where they want to.
What is the wind angle?
The angle between the ground vector and the wind vector, either negative or positive depending on clockwise or not.
What is the relative wind angle?
The angle between the air vector and the wind vector, either negative or positive depending on clockwise or not.
What is the Q code for magnetic bearing TO a beacon?
QDM.
What is the Q code for magnetic bearing FROM a beacon?
QDR.
What is the Q code for true bearing TO a beacon?
QUJ.
What is the Q code for true bearing FROM a station?
QTE.
What is cross-track (XTK), and what is a good rule of thumb for estimating it?
Cross-track is how far off of a radial an aircraft is flying. For each 60NM away from the beacon, 1 degree of track angle error (TKE) will result in 1NM of cross-track.
Which 5 approach methods are precision-capable?
GBAS GNSS ILS MLS Precision Approach Radar SBAS GNSS
What are the 5 stages of an instrument approach?
An arrival route (if needed)
An initial approach fix/point and segment
An intermediate approach point/fix and segment
A final approach point/fix and segment
A missed approach which leads either back to the initial approach, or to the traffic pattern
What is the minimum obstacle clearance during the different stages of the instrument approach procedure?
Initial approach is 300m, intermediate approach is 150m, final is bespoke to each route, and missed approach is get back to 300m as soon as possible please.
What are racetrack and reversal procedures?
Sets of instructions for navigation when landing at airports with only one navigational beacon to work with. Procedural.
What are obstacles described with reference to on approach charts?
Altitude and also to the elevation of the runway threshold, for the benefit of radio altimeter users.
What determines the minimum obstacle clearance on the final approach segment?
The ICAO approach category of the plane, the type of instruments being used to navigate the approach, the type of altimeter being used, and how straight the approach route is.
What information does a GPS deliver? 7 answers.
Distance to a waypoint Desired track Bearing to a waypoint Ground speed Actual track Estimated time en-route Cross-track
What is the order of preference the FMS has for updating its IRS position information?
Order of priority is GPS, then DME/DME, then VOR/DME, then IRS only, if nothing else is there.
What is the EPU reading of an FMS? Why is it important?
The EPU is the Estimated Position Uncertainty, which is how inaccurate the FMS believes its position data could be. It is important, because it needs to be compared to the required navigation performance for the route, and cannot go higher.
As an example, a plane flying an RNAV 5 route cannot have an EPU of more than 5 miles, or else it cannot be confident it is actually on the route.
What are the benefits of using performance based navigation over conventional navigation? 14 answers.
Improves safety Reduces hitting terrain Consistent and predictable flightpaths Stabilised approach paths Improves operating returns Reduces fuel cost Reduces cost on ground based systems Reduces time in flight by allowing more direct routes Increases airspace capacity Allows more traffic in a certain area Reduces airspace conflicts Is environmentally friendly Reduces radio transmissions Fewer go-arounds
