Do you have the patch1 and the FS98 converter installed? The VOR tailoff
reception was modified by the converter program. Usually, if the VOR is at the
airport, there shouldn't be any problem maintaining contact during a normal
approach pattern or glide slope. if you are in hilly or mountainous territory,
the reception will be interupted if the "line-of-sight" to the VOR is not
possible. The VOR reception distances in FS95 were not realistic on either end
of the scale.
FS98 uses a more realistic model for VOR reception than previous versions (of
course, its still not perfect). There are three classes of VOR's: terminal,
low altitude, and high altitude. Terminal VOR's are usually not used on Victor
airway segments, only as approach aids. They have a maximum required range of
25 NM beginning at 1500' AGL and are only usable up to 18,000' MSL. Low
altitude VOR's have a maximum required range of 40 NM, with the same altitude
restrictions. High Altitude VOR's are useable to 80NM below 18,000' and a good
deal more above (I can't remember the exact number, but I think it's 200NM).
Also, the 22 NM requirement you are talking about is for instrument navigation
along Victor airways
when you are flying
at or above the Minimum Obstruction
Clearance Altitude (MOCA). The MOCA guarantees you obstacle clearance and VOR
reception within 22 NM. You can look all of this up in the Airman's
Information Manual, which I've seen copies of at every library I've ever been
too. You can tell what type of VOR you're dealing with (T, L, H) by looking it
up at AirNav.
As a real world example, Westheimer Airpark (OUN) in Norman, Oklahoma is only
10 NM from the Will Rogers high altitude VORTAC, but you cannot receive a
signal until you are several hundred feet in the air.
Michael D. Klatt