Welcome Guest. Sign in or Signup

6 Answers

VOT VOR Test Facility

Asked by: 46930 views , ,
Flight Instructor, Private Pilot

When we are testing our VOR's on the ground to a VOR TEST FACILITY (VOT)  why does it not matter what position our airplane is on the airport in relation to the VOT?  I understand it only emits a radial beam on the 360 degree radial, and that we tune our OBS knob to 360 FROM or 180 TO for the indications.  

and

Is the VOT using the same facility as the VOR if the VOR is on the airport?  (i.e. KMKC)  Just a different frequency?

6 Answers



  1. John D. Collins on Mar 02, 2011

    This is not a precise detailed technical explanation, but hopefully you will get the idea.  The VOR transmits two signals, one is a reference signal and it is transmitted in all directions.  The second signal is encoded with the radial by using a phase shift. The phase shift signal is transmitted in only one direction for each radial with the direction and phase matching each other.  The aircraft receiver receives both signals, the reference and the radial phase signal.  The difference in degrees between the reference signal and the phase signal is the radial.

     

    In the case of a VOT, it transmits the reference signal and the phase signal for the 360 degree radial in all directions, so regardless where the receiver is, it will only detect being on the 360 degree radial.  Selecting 360 degrees as the VOT test radial makes sense because it means that both the reference signal and the radial phase signal are the same phase and it makes the VOT simple to construct.  I don’t know for sure, but I doubt the VOT would be housed close to an on field VOR, if for no other reason than to avoid interference.  I suspect it is a box in the communications equipment room somewhere on the airport.

    +27 Votes Thumb up 29 Votes Thumb down 2 Votes



  2. Ben on Mar 03, 2011

    Awesome explanation of VOT here – with visuals, also if you prowl around the rest of the website you’ll find many other useful animations and explanations:
    http://selair.selkirk.bc.ca/Training/instrument-rating/IFR-simulations/How-VOT-works.html

    +1 Votes Thumb up 1 Votes Thumb down 0 Votes



  3. Curtis Ide on Mar 05, 2011

    John gave a great explanation of VOT’s for you I just wanted to make an add-on question/answer.  I don’t have access to the Airport Facility Directory for your area today but I wanted to make sure you are using a VOT versus a VOR Ground Checkpoint.  If it is a VOR Ground Checkpoint on the field it will be listed in the VOR Checkpoint tab of the AFD and you will find a circle with an arrow inside located on the field.  In that case you would also be testing for a specific radial for that location not just the 360 and that radial would be located in the AFD as well.  In addition, many avionics maintainence facilities have a VOT box they can use to test the equipment in the shop and we have used them before to get a check in when the aircraft hasn’t flown in a while (we don’t have any other ground points on the field).

    +5 Votes Thumb up 5 Votes Thumb down 0 Votes



  4. Bill Dixon on Jun 08, 2011

    If you are identifying a VOR and hear T-E-S-T can you use that station?

    +1 Votes Thumb up 2 Votes Thumb down 1 Votes



  5. Kent Shook on Jun 09, 2011

    Bill,
     
    No. Any navaid broadcasting T-E-S-T is undergoing maintenance and the signal may not be correct, even if you are receiving it. See AIM 1-1-12.
     

    -1 Votes Thumb up 0 Votes Thumb down 1 Votes



  6. Timothy on Apr 25, 2015

    I’m trying find the nearest VOT test airports that are located here in NE Ohio. I know, check the AFD. I wonder if they are phasing them out. KCAK use to have one.

    0 Votes Thumb up 0 Votes Thumb down 0 Votes


The following terms have been auto-detected the question above and any answers or discussion provided. Click on a term to see its definition from the Dauntless Aviation JargonBuster Glossary.

Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.