Nav Flashcards
Navigation
What is the aim of Air Navigation?
To guide an aircraft through the air so that it arrives SAFELY, at the RIGHT PLACE, at the RIGHT TIME.
What 3 things lead to successful pilot-navigation?
1) Thorough and detailed pre-flight planning
2) A sound knowledge of Mental Dead Reckoning (MDR)
3) Accurate flying
What is a great circle?
A circle on the surface of a sphere (the earth) whose radius and center are those of the sphere itself.
What is a small circle?
A circle on the surface of a sphere (the earth) whose centre and radius are not those of the sphere.
Define the equator
The great circle on the surface of the earth whose plane is perpendicular to the axis of rotation of the earth.
What are meridians?
Semi-great circles joining the north and south pole.
What are parallels of Lattitude?
Small circles on the surface of the earth whose planes are parralel to that of the equator - joining points of equal lattitude.
What are rhumb lines?
A rhumb line is a regular curve on the surface of the earth that CUTS ALL MERIDIANS AT THE SAME ANGLE.
Distance is measured in nuatical miles.
Define 1 nm.
The length of the arc on a great circle which subtends an angle of one minute a the centre of the earth.
Assuming the Earth to be a true sphere.
What is the relationship between minutes and degrees?
60seconds=1minute, 60 minutes=1 degree
What is variation?
The angular difference between the direction of true north and magnetic north at any given point.
What are isognals?
Lines joining points of equal variation.
What is deviation?
The angular difference between the direction of Magnetic North and that of Compass North.
What are the 3 descriptors are used to distiguish individual maps?
1) Projection - the way 3D shapes have been represented in 2D
2) Scale - the size relative to the Earth
3) Topography - the nature of the detail recorded
Define a projection
“A systematic laying down of the earth’s meridians and parallels onto a flat sheet in such a way that the picture displays some of the features of the actual surface.”
The way the earth’s sphere is translated to a flat sheet!
What are the 2 types of generic projections?
1) Cyclindrical
2) Conical
What is scale and what are the 3 ways to specify it on a map?
Scale is the ratio of distance on the map to the real distance on the ground.
1) As a ratio, e.g. 1:250,000
2) As a statement, e.g. ‘the half mil map’ = 1:500,000
3) As a pictorial graduated scale
What is topography?
Topography is the detailed information recorded on the map.
What is Earth convergence?
The angle that one meridian makes with another.
Convergnece = zero at the equator
Meridians converge at the poles
What is Chart convergence?
The angle that one meridian makes with another ON A PROJECTION.
What are 3 types of charts/maps used for low and medium level Nav?
1) 1:500,000 Low Flying Chart (LFC) - military low level nav, conical projection
2) 1:250,000 (M5219) - UK Special Air Chart for both low and medium level nav, cylindrical projection
3) 1:50,000 OS Maps - target attack planning, detailed turning point info, transverse mercator
What chart is used for radio-aids nav?
The En-Route Chart (ERC)
Varrying scales
What is the CHAD?
Chart Amendment Document (CHAD)
PUBLISHED EVERY 28 DAYS
-informs flying units of significant corrections to aeronautical charts other than LFCs
What is the CALF?
Chart Amendment Low Flying (CALF)
PUBLISHED EVERY 28 DAYS
- lists changes to aeronautical info below 2000ft
- LFC and UK Special Air Chart ONLY
En-route Bulletin
Corrects: -ERCs -En-route suppliments -FIH PUBLISHED EVERY 28 DAYS
What are NOTAMs?
NOtice To AirMen issued frequently, allow the following amendments: 1) Obstructions 2)Danger Areas 3)Controlled AirSpace
Where should a track bearing be measured?
Mid-track
What are the 3 methods of expressing position?
1) Pin-Pointing
To name the point directly beneath an aircraft’s position.
2) Range and Bearing
Express aircrafts range and bearing from an easily identified datum or feature.
3) Grid Reference
Express aircraft’s position as a point of a grid system (latitude and longitude) e.g. British National Grid
What is lattitude and how it is measured?
The angular distance from the equator to a point, measured along the meridian that passes through that point.
Cannot be greater than 90 degrees N or S.
Given as 2 figures < 90
What is longitude and how is it measured?
The shorter angular distance between the Prime Meridian and the meridian passing through the point.
Expressed in degrees, minutes and seonds of arc E or W of the Prime meridian.
Cannot be greater than 180 E or W
Given as 3 figures < 180
Which of the six (BNG) primary zones are over the UK (land)?
NO
ST
What are the steps for map reading in CLEAR WEATHER?
Clock to Map to Ground
What are the steps for map reading in CLOUDY WEATHER?
Ground to Clock to Map
What are the 4 desirable characteristics of a navigation feature?
1) Unambiguous
2) Big (enough to be seen from the air)
3) Vertical extent for low-level nav
4) Easily identified
What is the frequency of position checks for the tutor?
Time bracket of 4 - 8 minutes
What are the 4 factors that could affect the frequency of position checks?
1) The availability of suitable landmarks when navigating visually
2) The availability of suitable beacons when navigating by radio aids
3) The length of the leg and the quality of the turning point
4) The need to have a safe, convenient work cycle, distributing your time between navigation, piloting the aircraft accurately and lookout.
What are the 3 uses of single position lines?
1) As a check on estimated time of arrival (ETA)
2) As a check on track made good
3) As a means of homing to a landmark, turning point or target (funnel feature)
What is the Safety Altitude a sum of? (SALT)
1) The elevation of the highest relevant obstacle
2) A combined safety margin for orographic errors and temperature/altimeter errors
3) A rounding up to the nearest 100ft
What is the sector error?
15nm either side of track and beyond the ends of track
What is the safety margin applied?
Obstacle < 3000ft - add 1000ft
Obstacle >/= 3000ft - add 2000ft
