42 votes
Accepted

How does TACAN work?

How is TACAN different from the VHF Omnidirectional Range (VOR) system? A very short question, but the answer calls for describing several techniques which are by themselves difficult to summarize ...
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  • 67.9k
34 votes

Does an aircraft carrier have a VOR onboard?

Aircraft carriers use a TACAN, which stands for Tactical Aid to Navigation. (The Navy is really good at making acronyms that don't follow normal conventions for abbreviation) Functionally the TACAN ...
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  • 16.4k
25 votes
Accepted

What is the night effect?

In short The night effect is actually a mirage. Listening to radio communications originating from below the radio horizon is like looking at a looming: Looming optical illusion, source: SKYbrary ...
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  • 67.9k
19 votes
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What radial is the aircraft crossing?

A radial is always pointing (radiating) away from the VOR. But your instrument shows the TO/FROM indicator as TO. So you are crossing a 210 course towards the VOR, which means you are on the 030 ...
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  • 45.9k
17 votes
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Is it possible for a civilian to use a VORTAC station?

Totally legal to tune it up & use it. If it is a VORTAC, it will work just like every other VORTAC out there. If it is a TACAN, you may be able to get DME from it, but you won”t get bearing from ...
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  • 42k
14 votes
Accepted

How can I triangulate a position using two DMEs?

We can find the exact method to use online, after all this is a common 3D trigonometry problem. I'll use Michael Geyer US DoT report: Earth-Referenced Aircraft Navigation and Surveillance Analysis. ...
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  • 67.9k
14 votes
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Are NDBs and VORs dying as a navigational method?

Yes, without a shadow of a doubt. Many airports now publish GNSS (Generic term for all types of satellite navigation) approaches, completly negating the need for those aids even during complex, ...
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  • 8,850
12 votes
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How wide is the cone of confusion above a VOR and NDB?

The value +/-40° is correct, but need to be interpreted. The primary reason of the existence of a "silence" (confusion) cone is a design choice to increase navaid range. Range and "...
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12 votes

How wide is the cone of confusion above a VOR and NDB?

Isn't it too much? No, it isn't. VOR's and NDB's are pretty old technology. VOR's were introduced in the 1930's and 40's, but are still commonly used today. If you have a cone of confusion of 45 ...
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12 votes

Why do we have to manually tune VOR receivers?

As pointed out in the comments, I think you have things turned around. If you select the frequency of a VOR that has a co-located DME, the system will automatically also select the DME frequency. Thus,...
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  • 38.7k
12 votes

Are NDBs and VORs dying as a navigational method?

Yes, it is true. This FAA page has more info. The Very High Frequency Omni-directional Range (VOR) Minimum Operational Network (MON) provides a conventional navigation backup service in the event of ...
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  • 7,230
12 votes
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Why don't hyperbolic navigation transmitters on the surface (e.g. Loran-C) allow altitude measurement?

You are correct, the time difference generates hyperboloids in 3D space and as such can be used to find the 3D position. However, if the transmitters are far apart and/or in the same plane, the ...
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  • 75.2k
12 votes
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What is Automatic Radial Centering on a VOR indicator?

As the name indicates, this automatically centers the CDI needle, by selecting the appropriate TO radial. From the manufacturer of INS 422, an integrated navigation system including a VOR: Pushing ...
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11 votes
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Are there two navaids on the same frequency close enough to be confused?

Short answer ICAO recommendations include a protection for same-frequency navaids, restricting the received power of undesired stations to a level preventing interferences. To meet this restriction ...
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  • 67.9k
11 votes

Why is the treatment of magnetic variation different for NDB and VOR?

The reason is, that for a VOR, the receiver in the aircraft determines the radial based on calculating the phase shift and as the VOR is oriented to the magnetic north of its location, we need the ...
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  • 271
10 votes

Why doesn't civil navigation equipment support TACAN?

Civilian aircraft can use part of TACAN, the Distance Measuring Equipment (DME) signal is the same as civilian DME. As for the directional component one big reason is that the military don't want you ...
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  • 50.2k
10 votes

Why would an ILS installation need a “reflecting surface” around the glideslope antenna?

You wrote that intuitively, one would expect that UHF-radio-wave-reflecting surfaces near your glideslope antenna would be a bad thing, due to the potential for multipath interference However, ...
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  • 2,406
8 votes

What is the difference between unserviceable, unusable, and not maintained?

UNSERVICEABLE (abbreviated U/S) is the ICAO version of what the FAA used to call OUT OF SERVICE (abbreviated OTS). To my mind this is less clear and a step backwards, but at least it's in line with ...
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7 votes
Accepted

What error is left uncorrected when "fast IRS align" is done?

Your question presumes that a "fast align" can be performed instead of a "full align", but is in some way deficient. But this is not the actual usage. Starting from cold (unpowered), the IRS must ...
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  • 3,711
7 votes

Is it possible for a civilian to use a VORTAC station?

Absolutely. A VORTAC is nothing more than a VOR colocated with a TACAN. Most VOR-DMEs in the US are VORTACs. If there happens to be one located on a base you are certainly still able to use it.
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  • 1,288
7 votes
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What are en-route VHF marker beacons (75 MHz)?

En-route marker beacons are close relatives of the outer/middle/inner markers used on ILS approaches. Airway markers use the same audio frequency as inner markers, and some older equipment has ...
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  • 69.8k
7 votes
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What are these FAA facilities in Seattle doing?

Seattle’s "golf ball" in Discovery Park was once part of the country’s Nike Hercules air defense system of missiles and radars in the 1950s. While most of the structures have been torn down, ...
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  • 2,324
7 votes

What is the answer to this question about aircraft position based on an NDB?

Yes, "D" is correct. A picture is worth a thousand words......
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  • 32.4k
7 votes

Why is the VOR reference and variable signal modulated at 30 Hz?

In VOR early days, the 40s, the stable phase locked loop frequency generator was not available. A common frequency reference was the very stable public AC power grid frequency. The angular velocity of ...
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  • 67.9k
7 votes

Does the radial needle of a HSI automatically deflect to the correct position when tuning the NAV radio to a localizer / ILS?

It depends on your instrument suite. If you have just a radio with connected HSI, you have to set the course yourself, because on the radio you only set the frequency and there are hundreds ILS ...
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  • 54.2k
6 votes
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Is Ground Direction Finding commonly used?

Yes, it is commonly used, especially in large complex airspaces. If two VHF direction finders are installed at sufficient distance from each other, they allow the ATC system to triangulate the ...
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  • 75.2k
6 votes

How does TACAN work?

Well, the short answer is that it operates in the same way as VOR except it uses UHF instead of VHF - and is therefore less subject to distortion - and always incorporates DME so a range and bearing ...
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  • 30.9k
6 votes

What are the differences between each ILS category?

The category specs are easily found on Wikipedia. Here is a concise view of the ILS approach minimums, as far as the crew is concerned. Cat I DH: 200 ft (61 m) or more RVR: 1,800 ft (550 ...
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  • 67.9k
6 votes

Just how inaccurate are (Las Vegas) VOR radials?

I guess it depends on what you consider to be a "high level of integrity and safety." VOR is a perfectly acceptable means of navigation if you know how to use it. And, I guess, if the transmitter hasn'...
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