Question 185-1 : The circumference of the parallel of latitude at 60°n is approximately ? [ Question security ]

Question 185-2 : Given position 'a' n60 w020 position 'b' n60 w021 position 'c' n59 w020what are respectively the distances from a to b and from a to c ?

30 nm and 60 nm.

At the equator 1° = 60 nmfrom a to b = 1° change of longitudedistance in nm for 1° change of longitude = 1° x 60 nm x cos latitudedistance in nm for 1° change of longitude = 1° x 60 nm x cos60° = 30 nmfrom a to c = 1° change of latitudedistance in nm for 1° change of latitude = 1° x 60 nm = 60 nm

Question 185-3 : The coordinates of the heliport at issy les moulineaux are n48°50' e002°165'what are the coordinates of the position directly on the opposite side of the earth ?

S48°50' w177°435'.

On the opposite side of the earth the latitude will be the same of our position but southon the opposite side of the earth the longitude must be west 180° 002°165' = 177° 435'if you want to check use the funny tool tunnel to other side of the earth

Question 185-4 : Isogonals are lines of equal ?

Magnetic variation.

1425isogonic lines connect positions that have the same variationagonic line a line which joins all points where the value of magnetic variation is zero

Question 185-5 : At a specific location the value of magnetic variation ?

Varies slowly over time.

Question 185-6 : Parallels of latitude except the equator are ?

Rhumb lines.

Question 185-7 : Given a is n55° 000°b is n54° e010°the average true course of the great circle is 100° the true course of the rhumbline at point a is ?

100°.

They specificaly state 'the average true course' 2479loxodrome track rhumb line true course between 2 points will be the same as the average great circle track orthodrome between those 2 points

Question 185-8 : Given position 'a' is n00° e100° position 'b' is 240° t 200 nm from 'a'what is the position of 'b' ?

S01°40' e097°07'.

On a bearing of 240°t from a to b it means the b will be south of a south of the equator and to the west of 100°e longitude less than 100°e only one answer satisfies this

Question 185-9 : The angle between magnetic north and compass north is called ?

Compass deviation.

Learn the composition of this table 1438

Question 185-10 : The north and south magnetic poles are the only positions on the earth's surface where ?

A freely suspended compass needle would stand vertical.

Question 185-11 : Value for the flattening of the earth is 1298 earth's semi major axis as measured at the equator equals 63784 kmwhat is the semi minor axis km of the earth at the axis of the poles ?

63569.

2062ratio of ellipticity e = a b a = 129863784 63784 298 = 635699 km

Question 185-12 : Morning civil twilight begins when ?

The centre of the sun is 6° below the celestial horizon.

Morning civil twilight is the period in the morning from the centre of the sun is 6° below the horizon until the upper limb of the sun appears at the horizon

Question 185-13 : How many small circles can be drawn between any two points on a sphere ?

An unlimited number.

Question 185-14 : An aircraft is following the 45°n parallel of latitude the track followed is a ?

Rhumb line.

Question 185-15 : A rhumb line on a direct mercator chart appears as a ?

Straight line.

On a direct mercator chart meridians are parallel equally spaced vertical straight lines 2054rhumb lines or loxodromes are tracks of constant true course

Question 185-16 : A great circle on the earth running from the north pole to the south pole is called ?

A meridian.

Question 185-17 : If you are flying along a parallel of latitude you are flying ?

A rhumb line track.

Question 185-18 : What is the rhumb line distance between two positions on latitude 60°n that are separated by 10° of longitude ?

300 nm.

10° x 60 nm x cos 60 = 300 nm

Question 185-19 : What is the length of one degree of longitude at latitude 60° south ?

30 nm.

1° = 60 nm on the equator1° = 60 nm x cos of latitude1° = 60 nm x cos 60 = 30 nm

Question 185-20 : The initial great circle track from a to b is 080° and the rhumb line track is 083° what is the initial great circle track from b to a and in which hemisphere are the two positions located ?

266° and in the northern hemisphere.

We can only be in northern hemisphere if great circle track is smaller than rhumb line track for easterly tracks 1462conversion angle is 3° 083° 080° it is half of convergency thus convergency is 6°our great circle track at b will be 086°initial great circle track from b will be 086°+180° = 266°

Question 185-21 : 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°.

Conversion angle = 12 g sin mean latitudewhere g = change of longitude = 10°w to 19°w = 9°12 x 9° x sin 45° = 318°we are going west so rhumb line is 270° and the great circle track at a 270° + 3° = 273°how to find if we have to add or retract the conversion angle correction 1462it's very simple look at the shape of a great circle track in north and south hemisphere

Question 185-22 : When the time is 2000 utc it is ?

1400 lmt at 90° west.

Lmt local mean timeyou must check all the answers 0800 lmt at the prime meridian wrong 20h00 gmt at prime meridian = 20h00 lmt at prime meridian2400 lmt at 120° west wrong 120° 4 minutes per degree 120 x 4 = 480 minutes 8h 20h00 gmt at prime meridian going west so minus 8h it is 12h00 lmt at 120° west1200 lmt at 60° east wrong 60° 4 minutes per degree 60 x 4 = 240 minutes 4h 20h00 gmt at prime meridian going east so plus 4h it is 24h00 lmt at 60° east1400 lmt at 90° west correct 90° 4 minutes per degree 90 x 4 = 360 minute 6h s20h00 gmt at prime meridian going west so minus 6h it is 14h00 lmt at 90° west

Question 185-23 : The distance along a meridian between 63°55'n and 13°47's is ?

4662 nm.

1° of longitude = 1 minute = 60 nm63°55' + 13°47' = 77°42'77° x 60 + 42 nm = 4662 nm

Question 185-24 : In which occasions does the rhumb line track and the great circle track coincide on the surface of the earth ?

On tracks directly north south and on east west tracks along the equator.

Question 185-25 : In the northern hemisphere the rhumb line track from position a to b is 230° the covergency is 6° and the difference in longitude is 10° what is the initial rhumb line track from b to a ?

050°.

The rhumb line track from a to b is 230° so the rhumb line from b to a is the opposite 050° 230 180 convergency and difference in longitude are useful for great circle calculation onlyremember rhumb lines or loxodromes are tracks of constant true coursegreat circle is the shortest distance between two points

Question 185-26 : How many degrees has the mean sun moved along the celestial equator in 8 hours and 8 minutes ?

122°.

The earth moves around the sun at a rate of 4 minutes per degree of longitude 15°h 8h x 15° = 120°8 minutes = 2°120° + 2° = 122°

Question 185-27 : 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 afor the track from b to a measured at b convergency between a and b = 8°great cricle track at b > great cricle track at agreat cricle track at b = great cricle track at a + convergencygreat cricle track at b = 040° + 8°great cricle track at b = 048°reciprocal of 048° = 228°

Question 185-28 : When flying on a westerly great circle track in the southern hemisphere you will ?

Experience an increase in the value of true track.

It's very simple first look at the shape of a great circle track in north and south hemisphere and at the equator 2051now take an example based on our question 2049when flying on a westerly great circle track in the southern hemisphere you will experience an increase in the value of true track

Question 185-29 : When the time is 1400 lmt at 90° west it is ?

1200 lmt at 120° west.

You must check all the answers 1400 lmt at 90° east wrong it can not be the same lmt for different longitudes1000 lmt at 60° west wrong 30° between 90° west and 60° west 4 minutes per degree 30 x 4 = 120 minutes14h00 at 90°west going east so plus 2h it is 14h00 lmt at 60° west0600 lmt at the prime meridian wrong 90° between 90° west and greenwich meridian 4 minutes per degree 90 x 4 = 360 minutes14h00 at 90°west going east so plus 6h at greenwich meridian it is 08h00 lmt1200 lmt at 120° west correct 30° between 120° west and 90° west 4 minutes per degree 30 x 4 = 120 minutes14h00 at 90°west going west so minus 2h it is 12h00 lmt at 120° west

Question 185-30 : 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.

The aircraft is flying on a westerly heading of 270° 2042the international date line idl is an imaginary line on the surface of the earth that runs from the north to the south pole and demarcates one calendar day from the next it passes through the middle of the pacific ocean roughly following the 180° longitude but it deviates to pass around some territories and island groupsthe international date line is on the opposite side of the earth to the prime meridian greenwich meridian the prime meridian helps to define universal time and is the meridian from which all other time zones are calculated time zones to the east of the prime meridian are in advance of utc up to utc+14 time zones to the west are behind utc to utc 12

Question 185-31 : The local hour angle of the mean sun at 1200 lmt is ?

000°.

In astronomy the hour angle is one of the coordinates used in the equatorial coordinate system for describing the position of a point on the celestial sphere the hour angle of a point is the angle between the half plane determined by the earth's axis and the zenith half of the meridian plane and the half plane determined by the earth's axis and the given point the angle is taken with minus sign if the point is eastward of the meridian plane and with the plus sign if the point is westward of the meridian planethe hour angle is usually expressed in time units with 24 hours corresponding to 360 degreesthe hour angle of a point on the earth's surface is the angle through which the earth would turn to bring the meridian of the point directly under the sun the earth is rotating so this angular displacement represents timeso in observing the sun from earth the solar hour angle is an expression of time expressed in angular measurement most usually degrees from the solar noonat solar noon at the observer's longitude on earth the hour angle is 0000 degrees with the time before solar noon expressed as negative degrees and the local time after solar noon expressed as positive degreesthe hour angle is the angular displacement of the sun east or west of the local meridian due to rotation of the earth on its axis at 15° per hour with morning being negative and afternoon being positivefor example at 10 30 am the hour angle is 225° 15° per hour times 15 hours before noon

Question 185-32 : Location a is at 50°n 030°w and location b is at 50°s 030°w 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.

In winter the northern hemisphere is tilted away from the sun at this time the sun is not directly above us days will be shorter and nights longer com encom061 552jpgin southern hemisphere this is summer and in northern hemisphere sunrise will be later and sunset will be earlier

Question 185-33 : An aircraft is flying a great circle track between waypoints number 4 45°00'n 040°00'w and number 5 45°00'n 030°00'w on arrival over waypoint number 5 compared to the true track at waypoint number 4 the true track has ?

Increased by less than 10°.

The aircraft is flying a great circle track which is on the pole side of the rhumb line 45°n com encom061 555jpgfrom 040°w to 030°w rhumb line is 090° true track at waypoint number 4 is less than 090°at 035°w we are at our highest latitude and at a true track of 090°our true track to reach waypoint number 5 is now more than 090° our true track has increased

Question 185-34 : Given variation is 6°w isogonic lines jan 2002 average annual increase 10'calculate variation in 2005 ?

65°w.

Variation 6°w in 2002 increasing 10 minutes per year2002 to 2005 = 3 years it is an increase of 30 minutes6° + 30' = 6°30'w 65°w in 2005

Question 185-35 : Position a = 56°000's 163°572'e position b = 56°000's 171°474'w for the route from a to b the ?

Great circle direction at b is 0807°.

com encom061 565jpggreat circle direction at b = 090° conversion angle 12 g sin lm g change of longitude approximatively 24° lm = mean latitude 56° great circle direction at b = 090° 12 x 24° x sin56° great circle direction at b = 080° rhumb line distance from a to b = change of longitude x cos latrhumb line distance from a to b = 24 x 60 x cos 56°rhumb line distance from a to b = 1440 x 0559 = 805 nm

Question 185-36 : Position a = 30°000'n 175°232'w position b = 30°000'n 173°481'e for the route from a to b the ?

Rhumb line distance is 578 nm.

com encom061 566jpggreat circle direction at a = 270° + conversion angle 12 g sin lm great circle direction at b = 270° + conversion angle 12 g sin lm g change of longitude approximatively 11° lm = mean latitude 30° conversion angle = 12 x 11° x sin30°conversion angle = 275° 3° great circle direction at a = 270° + 3° = 273°great circle direction at b = 270° 3° = 267°rhumb line distance from a to b = change of longitude x cos latrhumb line distance from a to b = 11 x 60 x cos 30°rhumb line distance from a to b = 660 x 0866 = 572 nm close to 578 nm

Question 185-37 : The first law of kepler states ?

Question 185-38 : What is meant by 'aphelion' ?

The point of the earth's orbit furthest away from the sun.

2477the aphelion is the point in the orbit of a planet or comet where it is farthest from the sun

Question 185-39 : Which statement about meridians is correct ?

A meridian and its anti meridian form a complete great circle.

Question 185-40 : A rhumb line from a position 86°n 30°w has an initial track of 085°t is it ?