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Questions tagged [radio-navigation]

Questions about aircraft navigation systems using radio signals, such as VOR and NDB.

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What limits automated direction finding from working over oceans?

Automated direction finders are only reliable in relative close proximity to NDBs, due to various adverse effects. In particular, the night effect limits their useful range for navigation ...
lxgr's user avatar
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7 votes
1 answer
2k views

Was radio navigation used for oceanic crossings before GPS? If not, why not?

As far as I understand, before the availability of GPS and other GNSSes, airplanes crossing large distances over water, beyond the range of ground-based navigation aids such as VORs and NDBs, largely ...
lxgr's user avatar
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4 votes
2 answers
746 views

Would I hear the 90Hz and 150Hz signals when tuned to ILS frequencies with a basic handheld radio?

If I were to make a basic handheld radio and set it to listen to any ILS, would I hear the frequencies which tell you whether you're left or right of the center line? On similar note, how come pilots ...
Lucas Dick 's user avatar
1 vote
1 answer
87 views

An Aircraft is a flight level 150 the DME is at sea level find maximum and minimum range?

I have taken this question from keith williams book. I know that we can find the maximum range of DME by line of sight formula which is R=1.23(Ht + Hr). But I don't know how to determine it's minimum ...
user75017's user avatar
4 votes
1 answer
270 views

What are the modulation parameters of a DME?

I am having difficulties finding specific information about DME pulse pair modulation. As far as I understand, the gaussian shaped pulse pairs are modulated using amplitude modulation. The carrier ...
keukenrol's user avatar
3 votes
2 answers
3k views

What's the difference between radial and bearing when flying VOR?

What is the difference or correct terminology for flying into a bearing (or radial?) when navigating by VOR? What is the difference? What is the correct lingo for VOR communication?
TheStophe's user avatar
  • 211
5 votes
3 answers
2k views

Why should the optimum position of GPS Antenna be close to aircraft's CG?

In CAE OAA Book11-Radio Navigation Chapter-18 Page-318, under GPS Error, "The optimum position for the antenna is on top of the fuselage close to the aircraft's centre of gravity". In the ...
Krishna Kanth's user avatar
-4 votes
2 answers
152 views

How do VOR beacons detect?

I assume that any military aircraft can find the position to any VOR ground station. Is the VOR invisible to the military aircraft?
knowledgeloverx's user avatar
0 votes
1 answer
236 views

Is QDM displayed wrong for the VOR in the aircraft?

Clearly, the VOR signals follow a great circle track. Since, they follow great circle tracks, the track to the station, measured at the aircraft (either, true or magnetic), would be different due to ...
Sachin Chaudhary's user avatar
0 votes
1 answer
429 views

Why if you tune localizer frequency the glide slope is tuned too?

if tuning the ILS you tune localizer freq which is between 108 MHz to 111.975 MHz. why the glide slope freq which operates in the 328.6–335.4 MHz band is tuned simultaneously?
Filip Adam's user avatar
0 votes
1 answer
243 views

For ADF, what is the point of phase shifting the loop or sense antenna before combining them to get the bearing of the NDB?

Why is there a need to phase shift the loop or sense signal by 90 degrees as after combining the loop and sense antenna reading, the direction of the NDB can be found by finding the maximum strength.
rdmalex ong's user avatar
7 votes
1 answer
6k views

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

Here are some NOTAMS for a recent flight I was planning: ...
rsteilberg's user avatar
2 votes
1 answer
82 views

Where can I find details about necessary system accuracy, integrity etc of a conventional navigation aid?

I am wondering where (probably in which ICAO document) can I find information about the required accuracy, integrity etc. for a conventional navigation aid for non-precision and precision approaches (...
Konrad's user avatar
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3 votes
1 answer
306 views

How does increasing the rate of pulse pairs in DME 'search' mode help?

From How does an airborne DME unit differentiate itself? The higher rate in SEARCH [150 PP/S] gives it more opportunity to detect the replies as it has no knowledge of range in search and thus has to ...
Sachin Chaudhary's user avatar
5 votes
1 answer
344 views

How do you calculate the deviation from an RNAV waypoint radial?

As a clarification at the beginning: I'm talking about non-GPS, pure VOR-DME based RNAV devices here. On RNAV devices that use just the selected VOR-DME, not GPS, the phantom radio station is set up ...
TheEagle's user avatar
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3 votes
0 answers
410 views

Why do DVORs and CVORs rotate in different directions?

I am currently studying both systems and I have the following doubt: why does DVOR rotate counterclockwise as opossed to CVOR? Could it be because the reference and variable signal are "swapped&...
A. R.'s user avatar
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8 votes
1 answer
1k views

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

Why in solving numerals of NDB and VOR, do we apply variation at the station in case of VOR and at the aircraft in case of NDB?
Sourabh Jain's user avatar
8 votes
1 answer
475 views

What is Automatic Radial Centering on a VOR indicator?

As the title says - some steam VOR indicators got an ARC indicator lamp. According to the POH of an aircraft featuring such a VOR indicator this means Automatic Radial Centering. What is that ? I ...
TheEagle's user avatar
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1 vote
1 answer
449 views

What are all the different ways pilots can navigate?

What are all the different ways pilots can navigate? What are they in simple terms and their unique advantages/disadvantages? EX: Dead-reckoning? VOR? GPS? ATC Directives? Others?
TayE's user avatar
  • 6,595
3 votes
0 answers
528 views

Is the Morse code identifier required continuously when using a VHF NAVAID for navigation?

I am thinking of getting an MGL N16 VHF Nav radio with the MGL Vega V16 Control head. It has an interesting mode of operation (referred to as SCAN Mode) where the single receiver in the N16 rapidly ...
Charles Bretana's user avatar
4 votes
1 answer
781 views

If the RMI heading rose is stuck, would the needle still display correct bearing?

If the RMI (Radio Magnetic Indicator) heading rose gets stuck, would the RMI needle still display correct QDM (magnetic bearing to station)?
Sachin Chaudhary's user avatar
3 votes
1 answer
946 views

Since modern ADF receivers don't rotate, how do they work?

Can you please explain the working of modern electric ADF recievers
Sachin Chaudhary's user avatar
1 vote
2 answers
3k views

Is QDR = QDM ± 180 always true in the case of an NDB?

If the magnetic variation at the aircraft and at the NDB station is different, then magnetic bearings would also change, so QDR = QDM + 180 would not be true. Can someone please help me understand ...
Sachin Chaudhary's user avatar
5 votes
1 answer
623 views

What does a DME indicator do in HOLD or RNAV mode?

I found this DME indicator on the Cessna 210. Its mode switch has four positions - NAV1, NAV2, RNAV and HOLD. NAV1 and 2 are clear - it uses the NAV1 and 2 freq respectively. I'm wondering what the ...
TheEagle's user avatar
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4 votes
3 answers
855 views

How does HSI decide to give a left or right CDI indication?

Since there is no reverse sensing in HSI, it tells you to turn left or right, So Is the interpretation correct that it will tell you to turn to the direction to that direction, which requires less ...
Sachin Chaudhary's user avatar
7 votes
2 answers
318 views

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

At least on small aircraft, the HSI is slaved to the NAV1 radio. The NAV1 radial is selected with a small knob of the HSI. Now, when I want to fly an ILS approach I don't need to set a radial myself ...
TheEagle's user avatar
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8 votes
2 answers
1k views

Are there two navaids on the same frequency close enough to be confused?

Several RTCA DO standards require checks for bad navaid tuning including, "In lieu of using ground-based navigation aid designated operational coverage (DOC), the system should provide, checks ...
RealAnswersNotAI's user avatar
7 votes
1 answer
2k views

What is the difference between a conventional and an RNAV holding?

While reading in the PANS-OPS (Doc 8168-OPS/611 Volume II) about holding procedures, I came across Chapter 7 of Part III section 3 defining RNAV holding procedures ...
Stelios Adamantidis's user avatar
8 votes
1 answer
2k 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?
Nish's user avatar
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4 votes
2 answers
395 views

Are VOR airways being replaced by RNAV routes as VORs are decommissioned?

I understand that VORs in the US and elsewhere are being removed from service gradually. The FAA plans to maintain a Minimum Operational Network, but still I imagine many VOR airways will also have to ...
asb1230's user avatar
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2 votes
4 answers
2k views

Selecting radials for radial interception

I’m a beginner in intrument flying so sorry for my ignorance. Few months ago I was doing BIR training and with my CFI we were intercepting radials, we were doing that on HSI (Garmin G500). He told me ...
Konrad's user avatar
  • 2,035
0 votes
0 answers
141 views

To what degree is CHAYKA radio navigation publically available?

With most of the Loran-C network in Europe shut off in Europe since 2015, public positioning services seems limited to satellite navigation (GPS/GLONASS/Galileo). However, to what degree is the ...
SE - stop firing the good guys's user avatar
1 vote
4 answers
17k views

What am I doing wrong in this RBI exercise?

The GYRO indicates the flight direction of the aircraft. The RBI indicates where the non-directional beacon(a location on ground that’s sending the plane signals) is located.  Top of the RBI is ...
user avatar
9 votes
2 answers
7k views

What radial is the aircraft crossing?

I'm working through the ASA Private Pilot 2020 Test Prep questions and there's a question I don't understand the answer for. 3579 (Refer to Figure 28, illustration 5) The VOR receiver has the ...
MrK's user avatar
  • 305
0 votes
4 answers
2k views

Do we need to know the true track to a VOR?

An aircraft can lock onto the location of a VOR and we can see the QDM (magnetic bearing to the station) to the VOR. If this is the case, do we still need to know the true track of that route? And if ...
Lungelo's user avatar
  • 35
2 votes
1 answer
284 views

Converting lat long & altitude into a line of sight target? [closed]

I want to design a long-range ADS-B receiver with a directional antenna (like a Yagi), but in order to maximize its range, I'll need to orient the antenna towards a target (plane) based on existing ...
John Wright Stanly's user avatar
11 votes
2 answers
2k views

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

According to the NTSB, the installation of a glideslope serving runway 11 at KHTS (Tri-State Airport, Huntington, West Virginia) was delayed for over twelve years by the lack of suitable terrain for ...
Vikki's user avatar
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16 votes
1 answer
3k views

Does an aircraft carrier have a VOR onboard?

I wouldn't think so due to the impracticality of VOR on a moving platform, but aircraft still need to navigate to the aircraft carrier. Would the radial shift around as the boat rocked around? The ...
user46251's user avatar
  • 347
4 votes
1 answer
223 views

Having trouble reading some charts (SBMG-SBLO)

I'm a flight sim user practicing instrument navigation with a short and apparently simple flight, SBMG to SBLO (South America). The distance between the two airports is 49.5 nautical miles (the ...
Douglas Silva's user avatar
4 votes
1 answer
238 views

Just how inaccurate are (Las Vegas) VOR radials?

I was discussing VOR-based navigation with a pilot, and he mentioned that VOR doesn't provide a very high level of integrity and safety (at least, compared to GPS or DME). He explained that the FAA ...
RealAnswersNotAI's user avatar
7 votes
1 answer
271 views

Why don't hyperbolic navigation transmitters on the surface (e.g. Loran-C) allow altitude measurement?

I have been reading the following article about radio navigation in general and GPS / GLONASS receiver design: A homemade receiver for GPS & GLONASS satellites in which the author states the ...
rkourdis's user avatar
3 votes
4 answers
9k views

What is the difference between a non-directional signal and an omidirectional signal from a radio aid?

NDB's are non directional and VOR's are omnidirectional. What is the difference between a signal that is non directional and a signal that is omidirectional, if any?
Skydemon's user avatar
  • 319
2 votes
1 answer
928 views

Why are the VHF and UHF airbands directly adjacent to frequency bands used by vital radionavigation aids?

Of the three main frequency ranges used by aircraft for radio communications (HF, VHF, and UHF), two (VHF and UHF) have their aircraft-radio-communications frequencies clumped together into a ...
Vikki's user avatar
  • 28.4k
4 votes
1 answer
197 views

Why would my transponder interfere with my ADF?

The ADF in my plane works very well until I switch the transponder to ALT. At that moment, the ADF needle is stuck in a random position and will not show the direction to the selected NDB anymore (the ...
Ze Jibe's user avatar
  • 265
2 votes
2 answers
2k views

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

An aircraft is intending to track from NDB ‘A’ to NDB ‘B’ on a track of 050° (T), heading 060° (T). If the RBI shows the relative bearing of ‘A’ to be 180° and the relative bearing of ‘B’ to be ...
milad's user avatar
  • 23
2 votes
1 answer
2k views

Does a GPS OBS selector use magnetic or true courses?

Under GPS navigation, when we are using the OBS to tune courses. Are these courses magnetic or true?
Darshan Patil's user avatar
1 vote
0 answers
155 views

What is the difference in purpose of the 1:40 Obstacle Identification Surface and the 1:50 clearance plane for an ILS glideslope?

I have found references to the Obstacle Identification Surface (OIS), which is approximately a 152ft/NM slope from the end of the runway (1.43 degrees, 1:40 rise/run) and a 1:50 clearance plane noted ...
Ryan Mortensen's user avatar
2 votes
2 answers
496 views

How does a TACAN signal change with bearing from the station?

In the TACAN system , how does a change in bearing , would translate to a change in the time (or frequency) domain. I'll try to elaborate: I'm aware , of the TACAN operation in general. let's say ...
Alex Rudyak's user avatar
2 votes
2 answers
745 views

Reason for the multiple sidelobes in an ILS glideslope signal

Why are there multiple side lobes in the glide slope signal from an ILS?
Vikas Singh's user avatar
2 votes
1 answer
5k views

What is the difference between an Non-Directional Beacon and a Compass Locator Beacon?

What is the difference between a Non-Directional Beacon and a Compass Locator Beacon?
Ryan Mortensen's user avatar