View Full Version : 2 Questions, Radio Navigation

8th Sep 2007, 15:30

Im going through the VOR chapter in Radio Navigation. I would be pleased if someone of you could explain and help with these 2 questions.

Question 1

An aircraft is on the airway bondary range 100nm from a VOR marking the airway centre line. Assuming that each dot equates to 2 degrees, how many dots deviation will be shown on the deviation indicator?

A) 3.0 dots
B) 2.5 dots
C) 2.0 dots
D) 1.5 dots

Correct answer is: D

Question 2

An aircraft is required to intercept and home to a VOR along the 064 Radial. The OBS should be set to:

A) 064 to get correct needle sense and a TO indication.
B) 244 to get correct needle sense and a TO indication.
C) 064 to get correct needle sense and a FROM indication.
D) 244 to get correct needle sense and a FROM indication.

Correct answer is: B



8th Sep 2007, 16:11
ok I get the question 2, but no idea of question 1...

8th Sep 2007, 20:24
If you do the trig:

arctan(5/100) = 2.86 degrees (5NM airway width, 1 in 60 rule)

If one dot is 2 degrees then deflection is 2.86/2 = 1.43 dots (Answer D)


8th Sep 2007, 21:16

You need the angle which is A, therefore: A=(60xD) / R
Range = 100nm
Airway boundary Distance = 5nm
(60x5)/100 = 3 degrees which is 1 and half dots..
If that makes sense..

9th Sep 2007, 09:57
mx4, if you battle with the second question, here's an easy way of remembering how to set up the OBS to intercept a radial.

I always teach FROM -> top TO -> bottom. Meaning:

If you intercept a radial to fly FROM a station, then the radial you wish to intercept must be on the TOP of the OBS, and a FROM indication must be showing.

If you wish to intercept a radial TO a station, then the radial ou wish to intercept must be set on the BOTTOM of the obs... i.e set the reciprocal on the top of the obs, and a TO indication must be showing.


Helped me!

9th Sep 2007, 10:44
..and always draw the helps no end..

9th Sep 2007, 10:57
Although it's fair to assume for the sake of an exam that the OBS is set to the airway track, the problem with question 1 is that it does not specify what the OBS is set to. Therefore, it is impossible to say what the needle will indicate.