VOR Question

VOR's are subject to blockage and "shadowing" caused by obstructions (hills, mountains etc.) and as a "rule of thumb" that I use, for VFR flight I usually anticipate the acquisition of a particular VOR at about 25 nm. For Hi-alt IFR, again, subject to coverage "Gaps", I usually anticipate the acquisition at about 50 - 75 nm.
I try to have at least two VOR's selected to give me a more precise triangulation to a given waypoint. If you go to a local FBO, sometimes, they will have an EXPIRED sectional chart of the area in which you are interested. These will have waypoints (intersections) shown that are the intersection of at least two fairly reliable VOR's.
I hope this helps you in your navigation efforts. Good Flying,

TDH

VOR Range
Ah, the oft asked and seldom answered question: how far away can I pick up a reliable signal from the Omni and what altitude need I be at? The FAA neatly skirts the answer by classifying Omnis by an altitude code, with the ranges vs. altitudes as shown in the table below.

Reception Range vs. Altitude of VORs VOR Class Range

Terminal (T) 25NM 1000 – 12,000 Feet

Low Altitude (L) 40NM 1000 – 18,000 Feet

High Altitude (H)
40 NM 1000 – 14,500 Feet
100 NM-14,500 – 60,000 Feet
130 NM-18,000–45,000 Feet
➡ http://www.navfltsm.addr.com/vor-nav.htm