estimate distance with degree change
Thread Starter
Joined: Dec 2000
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From: very close to STN!!
estimate distance with degree change
almost embarrassed to ask this, but i will anyway,
can anyone give me the equation or magic formula to work out the distance from an NDB when they give you two relative bearings, and time between the two bearing locations and TAS?
i can draw it and get the angles, but the formula for the distance escapes me and i don't have the old books that gave it back in the last ice age flight training.
i have dug through all the books i do have and its not there. have fished the net but couldn't find it either.
i know it must be simple, but to get it clear would help me for the nav tests feb 6th.
another question gave me the DME from the station and asked me to determine the distance between the two bearing locations.
has to be some isosceles triangle thing to it but i'm not related to Pythagaras that i know of.
cheers
can anyone give me the equation or magic formula to work out the distance from an NDB when they give you two relative bearings, and time between the two bearing locations and TAS?
i can draw it and get the angles, but the formula for the distance escapes me and i don't have the old books that gave it back in the last ice age flight training.
i have dug through all the books i do have and its not there. have fished the net but couldn't find it either.
i know it must be simple, but to get it clear would help me for the nav tests feb 6th.
another question gave me the DME from the station and asked me to determine the distance between the two bearing locations.
has to be some isosceles triangle thing to it but i'm not related to Pythagaras that i know of.
cheers
Joined: Feb 2001
Posts: 199
Likes: 0
From: South East
The 1 in 60 would be good for an estimate, and in your first question there are a few bits missing surely. Are you assuming that when each of the two bearings are taken that you are the same distance from the NDB? Also do you not need the GS as opposed to the TAS since the TAS will not give you a distance to work the equation (unless nil wind and ISA sea level conditions)
If so then take half the distance covered (x) and half the angular diference (y). You should then be able to work out the range using x/Sin y=Distance from NDB
This is assuming the above points...
Second problem is very similar your distance is X the angluar difference is Y and the distance between the points is Z, use X=2(Sin(Y/2) x Z)
Its all the Tan Cos Sin rules realy plus some lateral thinking..
good luck I passed so anyone can!!
If so then take half the distance covered (x) and half the angular diference (y). You should then be able to work out the range using x/Sin y=Distance from NDB
This is assuming the above points...
Second problem is very similar your distance is X the angluar difference is Y and the distance between the points is Z, use X=2(Sin(Y/2) x Z)
Its all the Tan Cos Sin rules realy plus some lateral thinking..
good luck I passed so anyone can!!
