Most people assume modern airliners navigate purely by GPS. In reality we still lean on a whole stack of ground-based radio navaids (VOR, DME, NDB, ILS) the oldest of which trace their lineage back to the 1920s.
With the amount of GPS jamming around the world at the moment, there are regular stretches of a flight where the jet falls back to these older systems to work out where it is.
I first learned all this from a textbook full of static diagrams, and always thought it deserved better. So I built interactive, draggable animations for each one — VOR, ILS, DME, TCAS, SELCAL, phased arrays and more.
Happy to answer any questions about the tech or the flying! :)
jamesharding•1h ago
quibono•41m ago
How often would you say you get to do a non-ILS landing? I often wonder how common these are outside of North America (where I hear visual approaches are apparently way more common than in Europe).
And related to that, how often do you see VOR approaches in the wild?
jamesharding•37m ago
The vast majority of approaches are still using an ILS. Pretty much the only time we would use an alternative approach (most often RNAV or LPV, and rarely VOR) would be if an ILS is not available.
That said, in the US especially, controllers are quite keen to offer a "visual approach" as it then relieves them of the duty to maintain separation from the aircraft in front. This is a cultural thing in the US, and the rest of the world does not operate this way. Even when flying a "visual approach" in the US, the ILS is usually still radiating, and we often still fly the approach using the autopilot coupled to the ILS, just maintaining our own separation from other traffic visually.
jamesharding•33m ago
On the A320 which I flew at the time, even VOR approaches were flown using a coded approach path, with the VOR needle itself being used for crosschecking. In the sim, we fly them still to make sure we remember how to, but they are quite rare these days!