Questions tagged [frequency]

Questions about the different radio frequencies used for aircraft communications and navigation and the processes of selecting them.

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9
votes
1answer
506 views

Why do so many airports have the same CTAF frequency?

In the United States, many non-towered airports have CTAF frequencies (often shared with UNICOM as well) that tend to overlap with various other airports within a 50-100 nm radius, at least in more ...
2
votes
1answer
302 views

How do you figure out which frequency to contact approach on for a class bravo transition?

I'm about 20 hours into my PPL, so maybe I just haven't gotten to this part yet. Suppose I'm flying KFCM to KRNH and I want to request clearance across the bravo. How do I figure out which approach ...
7
votes
1answer
338 views

Question about congestion of the 1090MHz frequency

I'm no expert so there's likely to be a lot of mistakes in this post. ADS-B - Automatic Dependent Surveillance - Broadcast, (out) transmits (in) receives position data from/to other aircraft and to ...
8
votes
1answer
279 views

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

VOR signals radiated from the ground beacon are modulated at 30 Hertz. What is the reason behind this?
0
votes
4answers
598 views

How do I know which airports have ILS and for which runways?

I have been into flying for years but something I can't figure out is how do I, as a pilot, know if an airport I am going to has ILS, which runways would have it and why do only some have it but the ...
8
votes
3answers
298 views

Why are lower VHF frequencies used for towers?

So, why are usually lower VHF frequencies (around 118MHz to roughly 120MHz) used for towers and higher frequencies (around 130MHz to 136.975MHz) for ACC? What is the advantage of using lower ...
1
vote
0answers
39 views

What are the expected vibration frequencies in a co-axial rotor system with contra-rotating propellers?

I am trying to understand the frequency spectrum of a co-axial rotor system. Form now i have a RC helicopter with two sets of three gear systems arranged in parallel, The number of teeth are 7,23,27) ...
3
votes
2answers
294 views

Why would different crossing runways at one airport be on different radio frequencies?

In this answer the following image was included which shows that control of two crossing runways are on different radio frequencies. Source: AIP Denmark EK AD 2 - EKCH - AREA OF RESPONSIBILITY It ...
1
vote
3answers
161 views

Where can I find current downloadable tower, ground and approach frequencies for USA airports?

I have searched the FAA site and cannot find a spreadsheet with current freqs for airports, only incomplete lists. Online flight planning tools must get query-able current freqs on a monthly basis, ...
0
votes
0answers
316 views

What is the working principle of VFG [duplicate]

How does the VFG make various frequencies? And while it makes the other value of frequency, how the generator apply consistent 400Hz to the other component?
7
votes
3answers
1k views

What is a metering frequency and why would an airport have it?

I just read a post from a pilot complaining about how he thought a metering frequency was useless. It has something to do with being on the ground at an airport. What is it, what purpose does it ...
1
vote
0answers
63 views

Why does airnav list frequencies for some STARs on the airport info page?

I was on airnav.com and looked up the info for KIWA. Why does airnav list frequencies for the arrivals (STARs) that serve an airport? Does each frequency correspond to a certain TRACON sector?
8
votes
4answers
2k views

Why do localizer/glideslopes use 90/150Hz specifically?

Why is it that localizer and glideslope system are using 90 Hz and 150 Hz frequencies only, instead of some other LF such as 75 Hz? Part two of my question: How does the modulation depth differ for ...
3
votes
1answer
222 views

What is the tolerance of SSR against signal frequency shifts?

I know that the Secondary surveillance radar (SSR) interrogates at 1030MHz, and the reply is at 1090MHz. What happens if the radio signal sent to the plane is less than/more than 1030MHz? Also what ...
8
votes
2answers
861 views

How do I find all the frequencies for my local TRACON?

I'd like to program my hand held radio with all frequencies that I can expect to need around my area. Specifically, I'd like to find an official list of all the frequencies used by the local Tracon ...
1
vote
4answers
1k views

Is there a radio frequency that is sure to be quiet?

When flying in beautiful VFR weather, I often search for a quiet frequency so I don't listen to a lot of chatter. Guard (121.5) sometimes works, but sometimes has "Guard"-ians on it. ("Yer on gaaard")...