A quick important disclaimer — the following information does not carry over into Infinite Flight as of update 21.8, and all VORS behave and can be utilized in a uniform manner in-app. You might not know it from Infinite Flight alone, but VORs come in a few different varieties.
There are two different types of VORs in real-life.
The Plain VOR
A navigation station that provides azimuth reference information so that you can determine your relative position to the station. Second is the VOR/DME, which is a VOR with the added capability of DME, distance measuring equipment. This type of VOR station allows aircraft with a DME receiver to reference their slant range distance to the station.
A VORTAC provides the same added distance information that a VOR/DME does, but instead uses the military TACAN equipment to do so as opposed to DME. This requires
different receiving equipment than a DME
receiver. Each VOR, no matter which type,
is also classified by their standard service volume (SSV). A service volume is a three dimensional area inside which, if tuned to the VORs correct frequency, it can the VORs correct frequency, it can be guaranteed that you will be receiving
that VOR and that VOR alone. Think of
service volumes as midair cylinders with
certain sizes defined by radius and altitude.
Currently, there are three types of service volumes, and each VOR is bound to only one of the three. They are Terminal, Low, and High.
Terminal VORs have the smallest service volume- a 25NM radius from 1000 to 12000 feet.
Low VORs have a service volume of a 40NM radius from 1000 to 18000 feet.
High VORs have the largest service volume by far- a 40NM radius from 1000 to 14500 feet, a 100NM radius from 14500 to 18000 feet, a 130NM radius from 18000 to 45000 feet, and a 100NM radius from 45000 to 60000 feet.
How can you find this information for a given VOR? VOR types are charted with different symbology on VFR and IFR enroute charts, for example.
This information, along with service volume type, can also be found in associated Chart Supplements.
Does any of this information matter for use in Infinite Flight? No. All VORs in Infinite Flight have an unlimited service volume and are classified simply as VOR in-app, regardless if they might be a VOR/
18000 feet. I hope it was interesting to learn that there’s a lot more that goes into VORs when it comes to our real-life navigation network.
Here’s what the regulation says:
(c) Operation below DA/DH or MDA. Except as provided in § 91.176 of this chapter, where a DA/DH or MDA is applicable, no pilot may operate an aircraft, except a military aircraft of the United States, below the authorized MDA or continue an approach below the authorized DA/DH unless –
(1) The aircraft is continuously in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers, and for operations conducted under part 121 or part 135 unless that descent rate will allow touchdown to occur within the touchdown zone of the runway of intended landing;
(2) The flight visibility is not less than the visibility prescribed in the standard instrument approach being used; and
(3) Except for a Category II or Category III approach where any necessary visual reference requirements are specified by the Administrator, at least one of the following visual references for the intended runway is distinctly visible and identifiable to the pilot:
(i) The approach light system, except that the pilot may not descend below 100 feet above the touchdown zone elevation using the approach lights as a reference unless the red terminating bars or the red side row bars are also distinctly visible and identifiable.
(ii) The threshold.
(iii) The threshold markings.
(iv) The threshold lights.
(v) The runway end identifier lights.
(vi) The visual glideslope indicator.
(vii) The touchdown zone or touchdown zone markings.
(viii) The touchdown zone lights.
(ix) The runway or runway markings.
(x) The runway lights.
What does this mean in less formal English? It means you can’t descend below minimums unless these three criteria are all met:
A. You can proceed normally to landing without having to do a ridiculous rate of descent or a 90 degree bank, for example.
B. The visibility that you are observing from the cockpit is at or better than the one in your approach.
C. You can see one of the 10 runway elements listed above.
If these three are met, you can proceed lower to land.