What is the distance between Alpha (S15 E120) andBravo (S15 E150)?
Please anyone with an explanation help me..
a)Greater than 900nm
c)less than 900nm
Way back in the 70's when I did my SCPL NAV (now ATPL) the syllabus covered a topic on Departure - the distance between to points on the same parallel.
In short, the formula for departure (in nm) was relatively simple: Departure (nm) = ChLon x Cos (Lat) where ChLon was the change in longitude in minutes.
In the example above, the distance (departure) between Alpha and Bravo can be calculated as follows:
Dep = ChLon x Cos(Lat)
Dep = 30x60 Cos 15 = 1738.7 nm
So the answer you want is > 900nm i.e. the answer is a
If the A&B were on the equator the distance between them would be: 1800 Cos 0 = 1800 nm - recall that one minute of longitude at the equator equals 1nm.
If A&B were at 90S the distance between them would be: 60 Cos 90 = 0 nm - meridians converge at the pole
With the above in mind, if you don't know the formula or can't use a calculator in the exam, you can reason that the distance between A&B will be a little less than 1800nm as A&B are on a parallel a little south of the equator.