Originally Posted by
sdfarook4
Aircraft heading 130 (M), has an adf reading of 190 relative, to intercept the 170(M) track outbound from an ndb at 30. The relative bearing to the ndb that confirms track interception is?
A) 150 relative
B) 140 relative
C) 170 relative
D) 160 relative
Answer is B. Pls explain
They say there are many ways to skin a cat. (I'm a cat-lover, BTW.) Having started my IR training in the good-old Link Trainer, and completed it in a Cessna 310 - neither of which were blessed with RMIs - I propose to set about this in a slightly different fashion from the excellent one used by
Mach Jump (above). Good thing is that we are sticking with magnetic bearings on this one, so the question can be done in your head (as you would normally do in the seat of an aeroplane).
Note that:
All tracks and headings in this exercise are magnetic (M);
QDR = magnetic bearing
from the beacon;
QDM = magnetic bearing
to the beacon;
the scenario seems to be in still air, so no drift - highly unusual.
Initial RB of 190 is equivalent to +10 as a bearing
from the beacon, so the present QDR = 140.
We want to intercept a QDR of 170, so we must turn to starb'd (right). A 30-degree intercept will involve a track of 200. So, as there's no wind, apparently, HDG = 200.
On reaching the QDR of 170 on a HDG of 200, the RB will be -30 (from), which is an RB of 150.
So the correct answer, IMO, is (A), not (B). Is that why you asked?
PS
In case anyone is confused by the above method of interpreting the RB needle, I'll try to explain.
If the head of the needle is pointing forwards relative to the a/c:
readings left of the nose are minus; readings to the right are plus. When applied to the present HDG, you get the QDM (magnetic bearing
to the NDB).
If the head of the needle is pointing aft:
readings left of the tail are plus; readings to the right of the tail are minus. When applied to the present HDG, you get the QDR (magnetic bearing
from the NDB.)