VOR Range
Thread Starter
Join Date: Sep 2005
Location: Not around here
Posts: 263
Likes: 0
Received 0 Likes
on
0 Posts
VOR Range
No doubt, the effective range of a VOR beacon will depend on your altitude, but is there a rule of thumb, or indeed, somewhere that officially has the info.
Regards,
C23
Regards,
C23
Join Date: Feb 2002
Location: East Midlands
Posts: 477
Likes: 0
Received 0 Likes
on
0 Posts
Join Date: Aug 2000
Location: S Warwickshire
Posts: 1,214
Likes: 0
Received 0 Likes
on
0 Posts
DOC only works if you have line of sight with the station.
Rule of thumb for line of sight (in NM) = sqrt(height in feet)
Assuming no big hills in the way etc.
e.g 2500' - 50NM
5000' - 70NM
Rule of thumb for line of sight (in NM) = sqrt(height in feet)
Assuming no big hills in the way etc.
e.g 2500' - 50NM
5000' - 70NM
Join Date: Aug 2000
Location: S Warwickshire
Posts: 1,214
Likes: 0
Received 0 Likes
on
0 Posts
The exact solution for length of tangent (assuming station at GL) is:
sqrt(2rh+h^2)
where r is the radius of the earth
and h is the height of the observer.
To a first order the h^2 term is negligible.
So length of tangent = sqrt(2r) * sqrt(height)
In nautical miles the coefficient works out at 1.0634
In statute miles it is 1.2245
So 1 is an easy conservative value for a rule of thumb.
sqrt(2rh+h^2)
where r is the radius of the earth
and h is the height of the observer.
To a first order the h^2 term is negligible.
So length of tangent = sqrt(2r) * sqrt(height)
In nautical miles the coefficient works out at 1.0634
In statute miles it is 1.2245
So 1 is an easy conservative value for a rule of thumb.
Originally Posted by Mark 1
The exact solution for length of tangent (assuming station at GL)...
In nautical miles the coefficient works out at 1.0634
In nautical miles the coefficient works out at 1.0634
Guest
Posts: n/a
The exact solution for length of tangent (assuming station at GL) is:
sqrt(2rh+h^2)
sqrt(2rh+h^2)
I'm sure for the ATPLs it was something like height of Tx + height of Rx (feet), square rooted, x 1.25. Anyone more current?
Bookworm,
The ATPL assumes line of sight.
Join Date: Aug 2000
Location: S Warwickshire
Posts: 1,214
Likes: 0
Received 0 Likes
on
0 Posts
Back to the original question....
For a rule of thumb, I prefer 1 as its easy to remember and slightly conservative.
I remember seeing 1.25 in one of the CPL text books, but this may be for a distance in stat. miles.
If the VOR is positioned significantly higher than the surrounding land then you can add a bit for this, as bookworm says.
Given the variability with local geography, I'd go for the conservative factor.
This is only for planning anyway. If you have a flag and ident, and are less than DOC distance, then it's OK to use it.
For a rule of thumb, I prefer 1 as its easy to remember and slightly conservative.
I remember seeing 1.25 in one of the CPL text books, but this may be for a distance in stat. miles.
If the VOR is positioned significantly higher than the surrounding land then you can add a bit for this, as bookworm says.
Given the variability with local geography, I'd go for the conservative factor.
This is only for planning anyway. If you have a flag and ident, and are less than DOC distance, then it's OK to use it.
Join Date: Sep 2003
Location: UK,Twighlight Zone
Posts: 0
Likes: 0
Received 0 Likes
on
0 Posts
Straight Line Propagation Paths - Direct or Space Wave
D (NM)=1.25(sqrt HTTX Station + 1.2 sqrt HTRX Station)
Example.
VOR 400ftamsl
Aircraft 5000ft amsl
D= 1.25 x (sqrt400 + sqrt5000) = 113.38NM
D (NM)=1.25(sqrt HTTX Station + 1.2 sqrt HTRX Station)
Example.
VOR 400ftamsl
Aircraft 5000ft amsl
D= 1.25 x (sqrt400 + sqrt5000) = 113.38NM
Join Date: Jun 2003
Location: EuroGA.org
Posts: 13,787
Likes: 0
Received 0 Likes
on
0 Posts
None of this ATPL ground school stuff is very relevant in practice, because if you potter about the UK at low levels you won't be receiving anything a lot of the time (except GPS) and if flying UK/European airways then ATC will send you all over the place and quite happily DCT some VOR which is way outside the DOC - they simply assume you have BRNAV which means a GPS.
It's the damned exams one has to get through
It's the damned exams one has to get through
Join Date: Feb 2002
Location: Hampshire, UK
Posts: 93
Likes: 0
Received 0 Likes
on
0 Posts
And to help complicate things a bit more:-
We ancient master mariners were taught:-
Distance of the horizon = (1.15 x sqrt H) + (1.15 x sqrt h)
Were H = Your height of eye and
h = Height of object (normally a ruddy lighthouse)
Although they did make a consession that a constant of 1.17 a better value for average conditions.
Just thought you ought to know.
We ancient master mariners were taught:-
Distance of the horizon = (1.15 x sqrt H) + (1.15 x sqrt h)
Were H = Your height of eye and
h = Height of object (normally a ruddy lighthouse)
Although they did make a consession that a constant of 1.17 a better value for average conditions.
Just thought you ought to know.
Guest
Posts: n/a
Given the variability with local geography, I'd go for the conservative factor...This is only for planning anyway. If you have a flag and ident, and are less than DOC distance, then it's OK to use it.
