I am new to aviation, so bear with me on this question:

I have read in multiple places that the VOR/NDB navigational aids are dying out to GPS. Is this true? Are more modern aircraft being built with glass, digital instrument readouts that capitalize on GPS services instead of the traditional vacuum tube ADF and VOR Indicators?

  • "traditional vacuum tube ADF and VOR Indicators" Tubes? Pretty sure there are no vacuum tubes in the indicators. Tubes wouldn't do well in the vibration environment of an airplane. – CrossRoads Sep 14 at 13:17
up vote 12 down vote accepted

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, critical phases such as approach and landing and take off and departure.

Modern GNSS systems are capable of utilising synthetic VORs where even when doing something such as flying a particular radial, the aircraft actually uses it's GNSS data to do so.

And, if you needed outright evidence, how about this quote from the UK National Air Navigation provider (NATS):

Commercial aviation – which has always funded the upkeep of the VOR beacons – now almost exclusively relies on the use of satellite navigation (read last week’s post on EGNOS for an example), making the majority of beacons an expensive and unnecessary financial burden. As such by 2020 we will be reducing their number from 44 down to 19.

Source: https://nats.aero/blog/2015/05/has-gps-killed-off-the-vor/

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    I'd suppose it would help cut down on expensive infrastructure as well. Reduce the number of giant VHF radio structures and NDB antennae helps keep $$ low...... – Jon Aug 29 at 18:56
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    @Jon Absolutely, see my edit :) – Dan Aug 29 at 18:56
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    The thing that terrifies me, is the satellites could become a prime target for an enemy/terrorist org. What would happen if all satellite-driven services died due to an attack? Are there alternative navigational methods in that worst-case scenario? – Jon Aug 29 at 18:57
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    @Jon I think that'd be a good candidate for another question if it hasn't been asked already. Suffice to say, yes - if nothing else, most modern aircraft are equipped with Internal Navigation Systems allowing navigation with no outside help at all – Dan Aug 29 at 18:58
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    @Jon If there is terrorist activity that is capable of knocking out enough navigation satellites to render GPS useless, the word "terrorist" has to get replaced with "well funded state actor." Also, when a well funded state actor decides to take out navigation satellites, that's a great time to be on the ground, at a pub... or maybe a basement. Basements are nice safe places =) – Cort Ammon Aug 30 at 0:24

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 a loss of Global Positioning System (GPS) signal. The MON includes the minimum number of geographically situated VORs in the contiguous United States (CONUS) necessary to provide coverage at and above 5,000 feet above ground level. Additionally, the MON supports International Oceanic Arrival Routes and mission critical military use.

From the Federal Radionavigation Plan the Gerry references in the comments:

ILS

ILS is the standard precision approach system in the U.S. and abroad. FAA operates more than 1,200 ILS systems of which approximately 150 are CAT II or CAT III systems. In addition, DoD operates approximately 160 ILS facilities in the U.S. Non-Federal sponsors operate fewer than 200 ILS facilities in the U.S.

As the GPS-based augmentation systems (WAAS and GBAS) are integrated into the NAS, and user equipage and acceptance grows, the number of CAT I ILSs may be reduced. FAA does not anticipate phasing out any CAT II or III ILS systems.

The NAS includes more than 1,300 NDBs. Fewer than 300 are owned by the Federal Government; the rest are non-Federal facilities owned predominately by state, municipal, and airport authorities.

NDBs

FAA has begun decommissioning stand-alone NDBs as users equip with GPS. NDBs used as compass locators, or as other required fixes for ILS approaches (e.g., initial approach fix, missed approach holding), where no equivalent ground-based means are available, may need to be maintained until the underlying ILS is phased out. Some NDBs may also need to be maintained to facilitate training and proficiency requirements. Most NDBs that define low-frequency airways in Alaska or serve international gateways and certain offshore areas like the Gulf of Mexico will be retained.

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    For the rest of the story, read the Federal Radionavigation Plan. – Gerry Aug 29 at 21:08
  • @Gerry Interesting document. I’ll have to read it in detail later. One thing that I did not know is that GPS signals are used by spacecraft. – JScarry Aug 30 at 0:33

In the case of VORs, maybe as a primary means of navigation it is dying out, but I honestly do not see them being phased out completely within the next decade or so. Most ANSPs prefer keeping them as a secondary means of navigation given that GNSS still relies on GPS developed by the US military.

As for NDBs, I think I've seen only one or two that are still in existence, so yeah they're definitely out.

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