GPS approach/landing for airliners

[dominique]

http://www.nytimes.com/2010/08/27/business/27air.html?ref=technology

INS,VOR,ILS may go the way of the dodo but not handflying!

[Bone]

The Visual Approach is never going to go away!

I think this article was talking out of turn. They're calling it GPS approaches, when in fact what they were talking about was GPS routing. We've all been doing GPS approaches for years, but the routing has been along the standard old Jetways and Victorways.

The funny thing is, we don't actually tune in ground stations to fly the tradional J/Vways. GPS is used to navigate these routes with what we call a "GPS Overlay". This is where we actually use the GPS to track along the Jet or Victor route without tuning into the VORTAC/VOR stations. We plug the phonetic identifier's for the whole route into the FMS and Wallah!, a GPS overlay is constructed. If the GPS becomes disabled for some reason, the FMS defaults to it's "auto-tune" function, and reads the phonetic identifiers and starts auto-tuning into ground stations. In the auto-tune mode, the FMS will tune in three VORTAC/VOR stations and up to six DME's in the surrounding area, and basicly turns into an RNAV system. It never relies on one ground station for fix to fix navigation.

[dominique]

Thanks for the insight.

The article is confusing, i agree... I thought he was writing about final approach (cutting corners).

Would a GPS + altitude radar driven FMS able today to deliver the aircraft to the threshold in an unconventional approach (eg 90 deg) without ILS, at least theorically ?

[Bone]

Thanks for the insight.

The article is confusing, i agree... I thought he was writing about final approach (cutting corners).

Would a GPS + altitude radar driven FMS able today to deliver the aircraft to the threshold in an unconventional approach (eg 90 deg) without ILS, at least theorically ?

Yes. FMS/FMC's have vertical nav (VNAV) ability, although it's used mostly for enroute descents.

[stansdds]

GPS is nice and makes navigation much easier, but what if something happens to those GPS satellites and the system is disabled? I certainly hope that VOR and ILS will be maintained as back up systems.

[wiltzei]

As a piece of trivia, use of Boeing´s VNAV is authorized down to 50 feet AGL.

[dominique]

GPS is nice and makes navigation much easier, but what if something happens to those GPS satellites and the system is disabled? I certainly hope that VOR and ILS will be maintained as back up systems.

There's a strong builtin redundancy with 24 satellites providing triangulation. So failure looks improbable. Disabling is another issue as the US own the key so to speak...

I wonder if regional jets use INS ? Bone ?