Formulas

Question 1

Convergency

Answer 1

Convergency = Dist long × sin mean lat
Convergency = Difference between initial and final GC track

Question 2

Conversion angle

Answer 2

CA = 1/2 (convergency)
CA = 1/2 (diff longitude × sin mean lat)
CA = 1/2 (diff between initial and final GC track)

Question 3

Calculating Distance

Answer 3

1-both pos on meridian and anti meridian in same hemisphere : go through pole
90 - lat = dist 1
90 - lat = dist 2
Dist 1 + dist 2 = total dist

2-both pos on meridian and anti meridian in diff hemispheres
If by north pole:
90 - lat(N) = dist1
90 + lat(S) = dist 2
Dist 1 + dist 2 = total dist

Question 4

Departure(Dep) - East and West Distance
Only valid for positions in same Lat or distance between 2 points is less than 200nm

Answer 4

Departure(nm) = D Long × Cos Lat
Departure(nm) = Ch Long × 60 × Cos Lat

D Long in minutes

Question 5

RMI

Answer 5

RMI = RB + a/c heading

Question 6

Scale

Answer 6

Representative Fraction(RF) = Chart Length / Earth Distance

Question 7

Mercator Scale Calculation

Answer 7

ABBA
Scale denominator A × Cos Lat B = Scale denominator B × Cos Lat A

Question 8

Relative Bearing Indicator on Mercator Chart

Answer 8

RB + TH = GC QUJ +/- CA = RL QUJ +/- 180 = QTE

Question 9

RMI on mercator charts

Answer 9

ADF QDM +/- Dev +/- a/c Var = GC QUJ +/- CA RL QUJ +/- 180 = RL QTE

Question 10

Contant of Cone
Conical projection charts

Answer 10

Contant of Cone = Angular extent of chart / change of longitude

Question 11

Time

Answer 11

Time = Dist Long / 15

Question 12

Reduction in speed
Calculate when speed change must be performed in order to set a/c config appropriately

Answer 12

Distance = (delay(minutes) × OldGS × NewGS) / (Diff in GS × 60)