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26

The ILS works using two components, a localizer and a glideslope. The frequencies for the localizer are between 108.1-111.95 MHz and the glide slope between 329.15-335.0 MHz. These frequencies are the carrier waves that the modulation you mention takes place upon. A pilot is only concerned with the localizer frequency as the navigation equipment knows the ...


26

Well, most airlines do cross the ocean with GPS in today's world. That being said, most (if not all) transcontinental airliners, and many flying domestic routes as well, have what's called an inertial navigation system (a form of dead-reckoning where gyros and accelerometers are used to compute changes in position). The INS feeds into the flight management ...


23

The delay is not 50 milliseconds, but 50 microseconds. It takes some time for the ground equipment to decode the incoming signal, decide it needs to reply, and fire up its transmitter. In order for the distance measurement to be reliable, this inevitable delay needs to be precisely defined and the same for all DME stations. It also gives the airborne ...


20

The ILS is precise enough to allow landings in essentially zero visibility, including those performed by autoland. The ground based bits The vertical range is 1.4° (0.7° above glideslope, 0.7° below) and the horizontal varies, but is a maximum of 6° wide. What this means in terms of how many feet or meters off the centerline an aircraft is varies ...


20

We were crossing the seas centuries before GPS, INS or really any other form of modern technology. All you need is a clock, a compass and a sextant. And some largely-forgotten skills, like how to do math without a smartphone.


19

Short answer Do you find the null position, then assume it's 90 degrees from the beacon? That's correct. For the antenna pattern shown in the question, the angle between direction of nulls and peaks is 90°. When sensing a null (or a peak) there are two possible and opposite directions for the beacon. This ambiguity has to be removed. This could be done by ...


15

In the days before GPS, we routinely crossed the oceans using inertial navigation systems. The system I was familiar with used 3 separate inertial systems (Carousel was the brand name). You could choose to navigate by any single one, but the most common way of using them was to have the autopilot "average" the positions. You could also choose to exclude any ...


13

VOR stands for VHF Omnidirectional Range. It is a navigation beacon intended for civil use and provides a user with a radial to/from the station. It works on frequencies between 108.00 and 117.95 MHz. VOR/DME station PEK (Beijing): source: Wikimedia, author: Yaoleilei TACAN stands for TACtical Air Navigation, a military system that is similar to VOR but ...


12

Nice question. There are several ways how to get these information. http://www.fallingrain.com/: free to use, no registration needed. World database of the airports and waypoints. From these information you could easily make DB for waypoints. EUROCONTROL EAD (https://www.ead.eurocontrol.int/eadcms/eadsite/index.php.html): free to use, registration needed. ...


11

Many older Air Transport Airplanes have no GPS. I'm a pilot since 1970. I operated A330 for 5 years until 2000 without GPS. The average IRS position (Inertial Reference Systems) in the FMS was updated by DME/DME. On older airplanes we selected the DME Stations manually preferably with a 90 degree cut-angle to obtain an accurate update. A single VOR/DME ...


11

Source: FAA 6750.16E - Siting Criteria for Instrument Landing Systems The more common G/S antenna type works by reflecting the signal off flat ground, called "image type". A non-image type was not available in the 70s as it's a mid-90s invention (patent; IEEE).


10

ILS is can be very precise, but there are many factors that may compromise the precision. When all these factors are avoided, automatic landing with no visibility is reliably possible. The ILS installations are classified in three categories: CAT I: Category 1 allows for decision height (DH) no less than 200 ft (height, so above ground level). ILS creates ...


10

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, multipath interference is exacly what we want here. The antenna is mounted a certain height above ground and the aircraft receives both the "line of sight" and "...


9

Navigation receivers can be used as a fall back for regular VHF/HF radio transceivers Before data links, there were essentially two types of radio receivers in the flight deck, and this is still the case for most GA aircraft: "COM" used for voice communication, and "NAV" used to receive navigation signals. When COM transceivers fail, the pilot is left ...


8

To add a little more detail on the receiver side and how it's used; The localiser and glideslope signals are transmitted on different frequencies (the "carrier" frequency) and these are filtered out to leave a mix of 90Hz and 150Hz for each one. The 90 and 150 are then filtered out separately. If you have more 90Hz than 150Hz, you are too far left on the ...


8

I use the National Flight Data Center at http://nfdc.faa.gov I had to write them a letter explaining why I wanted the data (http://fplan.sf.net) and they provided me with a login. Now, every 56 days, they send me an email telling me there's an update available. Bad news: they recently switched from a flat file to some unbelievably convoluted xml format ...


7

Most aircraft cross the atlantic by GPS, usually with INS as backup. INS as the primary form of navigation is still used as well. Historically, a combination of dead reckoning and long range radio navigation systems were used on transatlantic routes. These include Decca, LORAN C and Omega. Omega was shut down in 1997, Decca in 2000 and LORAN C ceased in ...


7

Your supposition is correct. Tuning the paired frequency will allow you to receive DME information from the TACAN. If your DME tuning is through your VOR/ILS receiver, the VOR output will be flagged no computed data (NCD) as there's no VOR signal to receive. The DME will tune the appropriate paired frequency and the DME should display normal data. Having DME ...


6

You're right. From FAA Aeronautical Chart User’s Guide, NAVAIDS in a shutdown status have the frequency and channel number crosshatched. Use of the NAVAID status “shutdown” is only used when a facility has been decommissioned but cannot be published as such because of pending airspace actions. Image from FAA Aeronautical Chart User’s Guide, 12th Ed. ...


6

the purpose of the 50 microsecond delay is to eliminate the possibility of uncoordinated operation when the aircraft is very close to the ground station From AVweb - DME Basics Addendum I have not found a clear explanation for what is meant by "uncoordinated operation" in the context of DME. What follows is speculation: If you look at patents related to ...


6

There are no ship-based VOR's or TACAN's specifically dedicated to transatlantic flights. Transatlantic flights navigate using the inertial navigation system and GPS. TACAN's are used on board naval ships for military aircraft to find their way to the ships, but this is typically not for flights across the ocean.


6

The answer is "All of the above." The left hand side of this slide from a NASA Powerpoint deck pretty much covers your question. The full slide deck from the presentation can be seen here.


6

The chart supplement does list the magnetic variation of the VORs. Looking under the "radio aids to navigation" section for a nearby airport, it's listed at the end of the line, right after the elevation. BATTLE GROUND (H) VORTACW 116.6 BTG Chan 113 N45º44.87´ W122º35.49´ 160º 9.6 NM to fld. 253/21E. Another source is the radio fix and holding data ...


6

Actually it doesn't have anything to do with voice capabilities: 5-3-5. UNMONITORED NAVAIDs a. All VOR, VORTAC, and ILS equipment in the NAS have automatic monitoring and shutdown features in the event of malfunction. Unmonitored, as used in this order, means that the personnel responsible for monitoring the facility have lost aural and visual monitoring ...


5

Typically terminal VOR's do not have compass roses around them if they are strictly terminal VOR's. I can't find an example of one so I don't have an image for it. Edit I found an example: Source: SkyVector The DEN VOR has no compass rose, so its either a terminal VOR or they omitted the compass rose for clarity. There are two other VOR's in close ...


5

Let's have a look at documentation of actual modern IRS. It says (on page 6) that if GPS data is lost, it will maintain RNP0.1 for 8 minutes, RNP0.3 for 20 minutes and RNP1 for 2 hours. That means that in 8 minutes the error is no more than 0.1 nautical mile with 95% confidence, in 20 minutes it is no more than 0.3 nm with 95% confidence and in 2 hours the ...


5

The most obvious reason is that the ITU allocated the VHF and UHF bands for aviation purposes generally, and then aviation authorities had to split those limited bands into adjacent comm and nav sub-bands. If aviation had gotten separate ranges for nav and comm, then that would double the risk of interference from adjacent non-aviation users, plus it would ...


4

Another good one for airports and navaids: http://opennav.com/ - has VORs, waypoints, etc.


4

The range of the VOR is included in the Airport/Facility Directory data. High altitude VORTAC: (Source) Low altitude VOR DME: (Source) Terminal VOR DME: (Source)


4

The maximum angular offset for a LOC is 3° for FAA and 5° for ICAO. Everything else is named either LDA (FAA) or IGS (ICAO). In ICAO wording, any ILS which doesn't meet all ILS requirements is an instrument guidance system (IGS). Localizer type directional aid (LDA) is a designation used by FAA. Guidance /aid refers to the fact that this system is not a ...


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