Thread by @To70_Aviation

Hi Ruud,
Interesting question. Luckily, a lot has changed in the 5 years since that SESAR presentation. P-RNAV & B-RNAV are gone, for instance.
With SBAS (Space-Based Augmentation System), signal quality is continuously monitored and any degradation broadcast directly to users
/1

https://twitter.com/RuudHteB/status/1143071117646737408

So, what's the case here? Runways always have multiple approaches, either conventional, nav beacon, satellite based or GNSS procedures. And while many are implementing PBN, so far only Israel has implemented *active* use of PBN through the approach.

/2

If there’s an ILS approach (precise, reliable and proven method) pilots will fly it, the final approach usually done by radar vectoring. If it’s a RNAV/RNP approach connected to ILS (xLS) one can use GNSS for position updates or use DME nav beacons (excellent coverage in EU)
/3

But what happens when a GPS signal is jammed when a GNSS procedure is flown?

With RNAV, nothing.

ATC is responsible for monitoring system integrity and interfering when necessary. ‘Required navigation performance’ RNP includes self-monitoring and alerting.

/4

If that can’t be met, pilots switch to alternative means of navigation (during en-route and before final). Or break off landing, conduct a missed approach, a/o go around with different approach procedure. Or even go visual.
/5

But, as mentioned earlier in this thread, PBN down to the threshold is rarely flown.

Hope this answers your question!

/end