Airliners don’t land on the INS for a precision approach.
Sure; an ILS is flown using the ILS signals.
A VOR approach is flown using INS for lateral, and some mixture of INS and BARO VNAV for the synthetic glideslope.
A synthetic glideslope is also really common in higher end bizjets; I was speaking to one pilot I know only this morning. He has a synthetic glideslope to every runway in the Jepp database; flies just like an ILS. In new bizjets the guidance is WAAS GPS in both L and V.
But I bet you every European airliner will prefer ILS over LPV even if the minima were the same.
WAAS GPS is incredibly reliable
Unless jammed or otherwise interfered with 
Really anything can fail, but GPS approaches are the ones with the lowest failure rate.
If there’s a war and the GPS approaches are jammed, i’ll stay home.
With regards to GPS navigation and landing capability – Boeing’s GLS (GPS Landing System) making use of GBAS is certified for Cat IIIb landings (that means full autoland and rollout) since about 2005.
As far as company usage is concerned, the momentum is towards GLS not ILS. See: http://aviationweek.com/commercial-aviation/faa-targets-2018-gps-based-autoland-capability
Quite a few airliners now have LPV capability.
The aircraft in general these days are capable of it (built after a certain date due to WAAS fit) but certification for the operators is generally the holdup. The various xAAs make the approval process a massive pain in the proverbial, taking a full year of annual training cycles to do all the stuff in the sim and a load of a pain in the backside in terms of arse-covering SOPs written by the VOR-loving dinosaurs who used to set the ATPL exams.
I will always opt for an ILS over an RNAV as, due to company SOPs, it takes about 5 minutes less briefing and embuggerance in actually configuring the autoflight to fly it! On a clear day I will take a visual over any instrument approach if available because I like flying!
One of the big advantages of RNAV approaches in general is they avoid the various offset approaches you get with VORs and NDBs. The RNAV overlay for the NDB 24 at Edinburgh is a fun example – beautiful lateral and vertical path to align you perfectly with the NDB…which aligns you brilliantly with the parallel taxiway not the runway! A proper RNAV approach would leave you nicely in the slot at DA rather than needing a sidestep or a bit of manoeuvring to align with the runway which on a shitty day at minima is no fun whatsoever.
EFBs are another example of this regulatory attitude – they are regulated by people who need their grandchildren to show them how to use an iPad…
When I said that I would prefer an RNAV/LPV approach over an ILS I was talking about GA planes like my Cirrus, not about airliners. In the Cirrus an RNAV approach is easier to fly and less error prone.
And I will also prefer a visual always in VMC, because it’s more fun than automation, yes.
Peter wrote:
Having a GPS and declaring it in the equipment string doesn’t mean your AOC includes approval for RNAV approaches.
It should. You are not supposed to declare RNP capability that you are not permitted to use.
Shorrick_Mk2 wrote:
Boeing’s GLS (GPS Landing System) making use of GBAS is certified for Cat IIIb
do you have any link for this? as far as I know there is no GBAS ground station for anything better than CAT 1 currently, CAT II and III are under development only and not anywhere near certification. So I would be really surprised if Boeing have IIIB on the aircraft side, I doubt there are specs/TSO for that. Even if, nobody can use it due to lack of ground station
Did you read the link I posted up there?
http://www.boeing.com/commercial/aeromagazine/aero_22/737approach_story.html
to Shorrick_Mk2: read carefully, there is a comma between Cat IIIB autoland and GBAS. so no GBAS Cat IIIB….
