01 Basic of Navigation Flashcards
ATPL GEN-NAV
A ‘Kilometre’ is a unit of measurement equal to:
a 1/10,000 part of the meridian length from equator to pole.
Position “Elephant Point” is situated at (58°00’N, 135°30’W). Standard time for this location is listed in the Air Almanac as UTC -8. If sunset occurs at 00:57 UTC on 21st January, what is the time of Sunset in LMT?
15:55 on January 20th.
……………………………………….
Sunrise and Sunset times are in Local Mean Time.
Arc to Time Conversion for 135°30’W
= 135.5 x 4 minutes
= 542 minutes
= 9 hours 2 minutes
Conversion is from East to West therefore subtract:
00:57 UTC on 21st January
09:02
15:55 LMT on 20th January
Which statement is correct about the apparent solar day?
The apparent solar day is the period between two successive transits of the true Sun through the same meridian.
The angle between Magnetic North and Compass North is called:
compass deviation
……………………………
Magnetic/Compass = deviation. True/Magnetic = variation.
An aircraft is in the position (86ºN, 020ºE). When following a rhumb line track of 085º(T) it will:
fly via a spiral to the North Pole.
Given:
Waypoint 1: 60°S 030°W
Waypoint 2: 60°S 020°W
What will be the approximate latitude shown on the display unit of an inertial navigation system at longitude 025°W?
060°06’S
A nautical mile is equivalent to:
1852 metres
The first law of Kepler states:
Planets move in elliptic orbits with the sun in one of the foci.
……………………………
Kepler’s Laws of Planetary motion:
First: The orbit of each planet is an ellipse with the sun at one of the foci.
Second: The line joining the planet to the Sun, known as the radius vector, sweeps out equal area in equal time.
Third: The square of the time the planet takes to go around the Sun (its ‘year’) is proportional to the cube of its mean distance from the Sun.
‘Apparent time’ is:
based on the time of transit of the apparent (or true) Sun.
Isogrivs are lines that connect positions that have:
Isogrivs are lines that connect positions that have:
The duration of civil twilight is the time:
between sunset and when the centre of the sun is 6° below the celestial horizon.
The great circle distance between position A (59°34.1’N 008°08.4’E) and B (30°25.9’N 171°51.6’W) is:
5400 NM
………………………………….
Note that there is no common longitude, meaning the question can not be a simple change of latitude problem.
There is also no common latitude, meaning the question can not be a simple change of longitude either.
The next check will be the two longitudes. If these add up to 180° and they are in opposite hemispheres (East and West) then they are directly opposite each other.
Provided the two positions are also in the same Northern (or Southern) Hemisphere then the shortest route between the two points will be over the relevant Pole.
Flying north along one meridian to the North Pole and then south along another meridian is a ‘polar transit’.
The simplest method of calculating ‘polar transit’ distances is to:
- Add the two latitudes
- Subtract the sum of the two latitudes from 180°
- Multiply the solution (in degrees) by 60 (minutes) to convert to minutes along a meridian of longitude, and thus into nautical miles
N 59°34.1’ + N 30°25.9’ = 90°
180° - 90° = 90°
90° x 60’ = 5,400’ = 5,400 nm
When proceeding, on a given date, along a parallel towards the East, the moment of sunrise will occur one hour earlier every 15° difference in longitude when it is expressed in:
UTC
A great circle track joins positions A (59°S 141°W) and B (61°S 148°W). How does the great circle track change when flying from A to B?
It increases by 6°.
……………………….
Calculate Earth convergence using the equation Convergence = Chlongº x sine mean lat.
Apply the Earth convergence using the memory aid below:
trackin west tracking east
- / +
—————————- Equator
+ / -
Earth convergence = 7 x sine 60º = 6º
Southern hemisphere and tracking East (westerly longitude decreasing) = Increasing track direction.
The great circle track will increase by 6º.
The time difference in Local Mean Time between sunset at positions A (50°N, 120°E) and B (50°S, 120°E) on the 21st of November is:
some hours and the Sun rises earlier in B than in A.
An aircraft at latitude 02°20’N tracks 360°(T) for 685 km. On completion of the flight the latitude will be:
08°29’N
………………………..
A change of latitude of 1° = 60 NM, 1 minute of latitude = 1 NM.
Firstly, convert the ground distance from km into NM.
685 k m ÷ 1.852 = 370 NM (rounded up)
Convert this into minutes of arc.
370 NM = 370’
Convert this into degrees and minutes.
Change of Latitude = 370’ ÷ 60’ = 6°10’
The change of latitude is in a northerly direction (360°T) from a northerly latitude (N02°20’). Therefore, add the change of latitude from the original, known latitude to calculate the new, unknown latitude.
New Latitude = N02°20’ + 6°10’ = 08º30’
New Latitude = N08º29’ closest answer
The north and south magnetic poles are the only positions on the earth’s surface where:
a freely suspended compass needle would stand vertical
What is the change in longitude from point A (N45° E165°30’) to point B (N45° W155°40’)?
38°50’E
An aircraft at position 00°00’N/S 163°27’W flies a track of 225°(T) for 70 NM. What is its new position?
00°49’S 164°16’W
……………………….
The new position is S 00°49’ W 164°16’.
Background Information
There are several of this type of question in the question bank.
There are no calculations required, merely common sense and a process of elimination.
You are staring at the Equator at W 163°27’ and proceeding on a track of 225T, which is a westerly track.
Therefore, the final position must be SOUTH and WEST of the start point.
The two answers stating positions at N 00°49’ can be discarded.
Next, the position must be to the West of W 163°27’; therefore, W 162°38’, the position to the East of W 163°27’ can also be discarded.
This only leaves S 00°49’ W 164°16’.
Exam statistics
Assuming the Earth to be a perfect sphere:
a 1 minute arc of a great circle measured on the surface of the Earth will be of equal length wherever it is measured.
Given: The coordinates of the heliport at Issy les Moulineaux are N48°50’ E002°16.5’. What are the coordinates of the position directly on the opposite side of the earth?
S48°50’ W177°43.5’
………………………………
The latitude will be the same but South instead of North. The longitude will be 180º away: 002º16.5’E + 180º = 182º16.5’ so longitude = 360º - 182º16.5’ = 177º43.5W
The GMT of Morning Civil Twilight at (66º48’N, 095º26’W) on 27th of January is?
1436 GMT
Standard time for some areas is listed in the Air Almanac as UTC +13 instead of UTC -11. The reason for this is:
to keep the same date as the political and/or economical entity to which they belong.
Near the magnetic pole
the horizontal component of the earth’s magnetic field is too small to permit the use of a magnetic compass.
On which occasions do the rhumb line tracks and the great circle tracks coincide on the surface of the Earth?
On tracks directly North - South and on East - West tracks along the Equator.
Consider the following statements on the properties of a great circle:
A great circle running through two positions on the surface of the Earth is the shortest distance between these two positions.
When using latitude and longitude for a place:
the location of this place, on the Earth’s surface, is defined.
The Local Mean Time at longitude 095°20’W, at 0000 UTC, is:
1738:40 previous day
……………………………………..
Time: 00:00:00 UTC
95.3º x 4 mins: 6:21:20 “Longitude West Greenwich best”: take it away.
Time: 17:38:40 LMT previous day.
A route is drawn from 75°00’N, 060°00’E to 75°00’N, 030°00’W on a Polar Stereographic chart with the grid aligned with the Greenwich meridian. The Grid Track is:
255º(G)
…………………………….
Northern Hemisphere
Position east of the reference meridian: Grid = True - Convergence
Position west of the reference meridian: Grid = True + Convergence
Southern Hemisphere
Position east of the reference meridian: Grid = True + Convergence
Position west of the reference median: Grid = True - Convergence
No directional information is given but as A and B are on the same parallel of latitude then the Vertex is at the mid point.
Vertex at 015°E
True Track direction at the Vertex = 270°(T)
Convergence (at 015°E) = 15°
Northern Hemisphere and East of Reference Meridian
Grid Track = True Track - Convergence
= 270° - 15° = 255°(G)
One minute of an arc of a meridian is equal to:
1 NM
………………….
One minute of an arc of a meridian is equal to 1 nm.
Given: Compass Heading 233° True Track 256° Drift Angle 10°R Deviation -3°
What is the variation?
16°E ..................... True Track= 256° Drift Angle = 10°R Drift is FROM Heading TO Track, therefore: True Heading = 246° C D M V T 233° -3° 230° 16°E 246°
In order to fly from position A (10°00’N, 030°00’W) to position B (30°00’N, 050°00’W), maintaining a constant true course, it is necessary to fly:
a rhumb line track
The ‘departure’ between positions 60°N 160°E and 60°N ‘x’ is 900 NM. What is the longitude of ‘x’ when flying eastbound?
170°W
If an aeroplane was to circle around the Earth following parallel 60°N at a ground speed of 480 kt. In order to circle around the Earth along the equator in the same amount of time, it should fly at a ground speed of:
960 kt
If the Compass Heading is 265°, variation is 33° W and deviation is 3°E, what is the True Heading?
235° ..................... CH: 265º Dev: E03º MH: 268º VAR: W33º TH: 235º
A rhumb line from a position 86°N 30°W has an initial track of 085°T is it:
a spiral to the North pole
What is the time required to travel along the parallel of latitude 60° N between meridians 010° E and 030° W at a groundspeed of 480 kt?
2 HR 30 MIN
………………………..
ChLong = 40º. Departure = 40º x 60 x cos60º = 2400 x 0.5 = 1200nm
1200/480 = 2.5 hours.
Which of the following statements regarding meridians is correct?
Meridians are parallel only at the equator.
Use the Air Almanac Tables.
The UTC of sunrise on 6th December at Winnipeg, Canada (49°50’N 097°30’W) is:
1413 .................... The almanac gives the time on the nearest day and latitude as: Sunrise at 50ºN 07:43 LMT 97½ºW at 4 min/º 6:30 Sunrise at 50ºN 14:13 UTC
The maximum difference between geocentric and geodetic latitude occurs at about:
45° North and South.
Use the Air Almanac Tables.
When it is 0600 Standard Time in Queensland (Australia) the Standard Time in Hawaii (USA) is:
1000
The reason that the solar day lasts longer than the sidereal day is that:
both the direction of rotation of the Earth around its axis and its orbital rotation around the Sun are the same.
An aircraft at position 60°N 005°W tracks 090°(T) for 315 km. On completion of the flight the longitude will be:
000°40’E
An aircraft’s position is give as 80°00’S 140°00’E and it is tracking 025° (G).
If the grid is aligned with the Greenwich Anti-Meridian, the true track is:
065°T
The main reason for the occurrence of seasons on Earth is:
the inclination of the Earth’s axis with regard to the plane of the ecliptic.
At 0000 Local Mean Time of an observer:
the mean Sun is in transit with the observer’s anti-meridian.
On the 27th of February, at 52°S and 040°E, the sunrise is at 0243 UTC. On the same day, at 52°S and 035°W, the sunrise is at:
0743 UTC
…………………………
The Earth moves around the Sun at a rate of 4 minutes per degree of longitude. The question is asking for the time of sunrise at the same latitude (52ºS), on the same day (27th February) after travelling through 75º change of longitude (from 040ºE to 035ºW):
Sunrise at 52ºS 02:43 UTC at 040ºE on 27th
75º Ch Long at 4m/º 5:00
Sunrise at 52ºS 07:43 UTC at 035ºW on 27th
An aircraft flies a great circle track from 56°N 070°W to 62°N 110°E. The total distance travelled is?
3720 NM”
You are flying from A (N50° W010°) to B (N58° E002°). If the initial great circle track is 047°T what is the final great circle track
57°
The direction of Magnetic North at a certain position coincides with the direction of:
the horizontal component of the Earth’s magnetic field.
Location A is at 50ºN 030ºW and location B is at 50ºS 030ºW. On 27th November it is noted that:
sunrise will be later at A than it is at B and sunset will be earlier at A than it is at B.
Which one of the following statements about rhumb lines is most correct?
Most rhumb lines will run as spirals from one pole to the other.
An observer is situated on the parallel of 23.5°S. Which statement about the passage of the apparent Sun in relation to this position is correct?
It passes through the zenith once a year around December 22nd.
…………………………….
Zenith is a position in space that is directly above the observer. The sun will only be directly above S23º30’ once every year, namely at the winter solstice around the 22nd of December.
Route A - B is drawn on a Southern Polar Stereographic chart whose grid is aligned with the Greenwich meridian. The true track of the straight line at A is 120°. When passing the meridian 100°E the true track is 090°. The grid track of this route on the chart is:
190º(G)
…………………………..
Convergence (at 100°E) = 100°
Southern Hemisphere and East of Reference Meridian
Grid Track = True Track + Convergence
= 090° + 100° = 190°(G)
(The True Track direction of 120° at A is irrelevant as the position of A is unknown)
A VOR is situated at position 74ºN, 094ºW. Local variation is 50ºW. A polar stereographic chart supplied with a Greenwich grid is used for navigation. To proceed along (magnetic) radial 238 inbound an aircraft has to follow a Grid Track of:
102º
………………………
Magnetic Track = 058°(M) remember INBOUND along the radial.
Variation West Magnetic Best
True Track = 008°(T)
Convergence (at 94°W) = 94°
Northern Hemisphere and West of Reference Meridian
Grid Track = True Track + Convergence
= 008° + 94° = 102°(G)
An aircraft departs from Schiphol airport (where ST = UT+1) and flies to Santa Cruz in Bolivia (South America) via Miami in Florida.
Departure time (off blocks) is 07:45 ST on the 10th of November.
Taxi time before take off at Schiphol is 25 minutes.
Flight time to Miami over the Atlantic Ocean is 9 hrs 20min.
Total taxi time in Miami to and from the gate is 25 minutes.
Time spent at the gate is 2 hrs 40min.
From Miami to Santa Cruz the airborne time is 6 hrs 30min.
Calculate the time and date of touch down in Santa Cruz, Bolivia (standard time) if the difference between ST and UTC is 5 hours.
(Note: use the information given, not ST tables)
21:05 10th Nov.
Morning Civil twilight begins when:
the centre of the Sun is 6° below the celestial horizon.
An aircraft at latitude 10°N flies South at a groundspeed of 444 km/hr. What will its latitude be after 3 hours?
02°S
A day at any place, as measured in local mean time, starts:
when the mean Sun transits the anti meridian of the place in question.
An aircraft passes position A (60°00’N 120°00’W) en route to position B (60°00’N 140°30’W). What is the great circle track on departure from A?
279°
When the length of the day is measured with reference to the passage of the apparent Sun:
the length of the day will vary in the course of a year.
Which statement is true?
The declination of the sun and the latitude of the observer will affect the duration of civil twilight.
A route is flown from 85°S, 100°E to 85°S, 140°W. At 160°E the Grid Track and True track on a polar stereographic chart with a grid orientated on the 180º meridian are, respectively:
070°(G) and 090°(T)
A great circle intersects the equator in 030°W with a great circle direction of 035°(T). An aircraft tracking the great circle will reach the maximum Northern/Southern latitude in position:
55°N, 060°E
The great circle bearing of position B from position A in the Northern Hemisphere is 040°. If the Conversion Angle is 4°, what is the great circle bearing of A from B?
228°
……………………………
The reciprocal of 40° is 220° and that is measured at A.
The question asks you for the track from B to A, measured at B.
Convergency between A and B = 8°
GCT at B > GCT at A
GCT at B = GCT at A + Convergency
GCT at B = 040° + 8°
GCT at B = 048°
Reciprocal of 048° = 228°
How does the convergence of any two meridians on the Earth change with varying latitude?
It changes as the sine of the latitude.
Deviation applied to magnetic heading gives:
compass heading.
The angle between the plane of the ecliptic and the plane of equator is approximately:
23.5°
…………………………….
The plane of the Earth’s orbit around the Sun. Because of the tilt of the Earth’s axis the Sun moves between being overhead the Tropics of Cancer and Capricorn at 23.5ºN and 23.5ºS.
What is the latitude of the polar circles?
66.5° N/S
……………………..
The principal latitudes on the Earth are:
- North Pole - N90°
- Arctic Circle - N66½°
- Tropic of Cancer - N23½°
- Equator - 00°* Tropic of Capricorn - S23½°
- Antarctic Circle - S66½°
- South Pole - S90°
The long term periodic change in the Earth’s Magnetic Field
is reflected in the slow movement of the magnetic poles.
………………………………
The magnetic poles are in constant, slow movement and it is this movement that cause changes in the Earth’s magnetic field over time.
In the Northern Hemisphere the rhumb line track from position A to B is 230°, the convergence is 6° and the difference in longitude is 10°. What is the initial rhumb line track from B to A?
050°
…………………….
If the rhumb line from A to B is 230 o the rhumb line from B to A is the reciprocal: 230 o - 180 o = 050 o.
The information about convergency and difference in longitude is of no relevance.
The Directive Force:
is the component of the Earth’s magnetic field which aligns the compass needle.
How long is 25km at 60°00’N?
13.5 nautical miles.
The variation at a position is 13°W and the true track is 136°.
Which one of the following statements is true?
The magnetic track is 149°.
An aircraft flies the following rhumb line tracks and distances from position 04°00’N 030°00’W: 600 NM South, then 600 NM East, then 600 NM North, then 600 NM West. The final position of the aircraft is:
04°00’N 029°58’W
An aircraft at latitude 02°20’N tracks 180°(T) for 685 km. On completion of the flight the latitude will be:
03°50’S
If you are flying along a parallel of latitude, you are flying:
a rhumb line track.
Which statement is true?
The declination of the sun and the latitude of the observer will affect the duration of civil twilight.
Which statement about ST is true?
Standard time is determined by the government of the appropriate state and does not necessarily follow the borders of 15° wide longitude zones.
A flight is to be made from A (49°S 180°E/W) to B (58°S 180°E/W).
The approximate distance from A to B is:
1000 km
………………………..
You are travelling along the Greenwich anti-meridian (180° E/W) between 49°S and 58°S.
Change of latitude = 58°S - 49°S (Same hemisphere = SUBTRACT)
Change of latitude = 9°
9° change of latitude x 60’ = 540’ change of latitude
In terms of change of latitude, 540’ = 540 nm
This answer is not on offer!
1 nm = 1.852 km
540 nm x 1.852 = 1,000km
The compass needle marked red:
is called ‘The North-seeking Pole’.
A flight is planned from A (N37°00.0’ W/E000°00.0’) to B (N46°00.0’ W/E000°00.0’). The distance in kilometres from A to B is approximately:
1000 km
……………………….
How many small circles can be drawn between any two points on a sphere?
An unlimited number.
What is a ‘vertex’?
The point on a great circle with greatest latitude.
If True HDG is 165° and variation is -3° what is the magnetic heading?
Variation is negative (Westerly), therefore magnetic heading is 168°.
An aircraft is following the 45°N parallel of latitude. The track followed is a:
rhumb line
The agonic line:
follows separate paths out of the North polar regions, one currently running through western Europe and the other through the USA.
Assume a North polar stereographic chart whose grid is aligned with the Greenwich meridian. An aircraft flies from the geographic North pole for a distance of 900 NM along the E090° meridian, then follows a grid track of 150°G for a distance of 480 NM. Its position is now approximately:
N70° E070°
“A” latitude is 00°N/S “B” is located at 33°N, 101°E. True track (great circle) from “A” to “B”, at “B”, is 090°. The initial true track of the great circle at “A” is:
057°
What is the meaning of the term ‘standard time’?
It is the time set by the legal authorities for a country or part of a country.
Which of the following alternatives is correct when you cross the International Date Line?
The date will increase if you are crossing on a westerly heading.
At what approximate date is the earth closest to the sun (perihelion)?
Beginning of January
For 1st February the Air Almanac lists the following data:
Latitude: N66°00’
Morning civil twilight: 0756
Sunrise: 0900
Sunset: 1528
Evening civil twilight: 1632
The duration of morning twilight at 66°00’N is:
1 hour 4 minutes and starts at 0756 LMT.
The horizontal component of the earth’s magnetic field:
is very small close to the magnetic poles.
The great circle track measured at A (45 00’N 010 00’W) from A to B (45 00’N 019 00’W) is approximately:
273°
When crossing the International Date Line, which of the following statements can be considered correct?
the date will increase crossing on a westerly heading
The circumference of the parallel of latitude at 60°N is approximately:
10 800 NM
What is the definition of magnetic variation?
The angle between True North and Magnetic North.
Route A - B is drawn on a polar stereographic chart with the grid aligned with the Greenwich meridian. The true track of the straight line at A is 060°. When passing the meridian 100°E, the true track is 090°. The grid track of this route on the chart is:
350º(G)
Which is the highest latitude at which the Sun will rise above the horizon and then set every day?
64°N
Preparing a chart for use of grid means:
selecting a meridian on the chart and drawing lines on the chart parallel to the meridian selected.
A negative (westerly) magnetic variation signifies that:
True North is East of Magnetic North