GNSS Landing System (GLS)?
 

Does anyone know where I might find detailed information about the workings of the GNSS Landing System (GLS) on the internet.?

I understand the concept of the Ground Based Augmentation System (GBAS) refining the aircrafts GPS position with error corrections, but I surmise this same system is somehow involved in the vertical navigation too.

The part that is not clear to me how the approach path is defined and how the aircraft determines it's vertical position in relation to that path. Does the aircraft utilise GPS altitude? Is this altitude only available with the assistance of the GBAS?

The fact that the GLS can facilitate autoland means the descent path and altitude is flown independent of the aircraft's FMC's and pressure Altimiters but nowhere can I find this stated as fact.

Thank you.

A found a lot of hits from a Google search under "GNSS Landing System".
HTH

You should have a look at ICAO Annex 10 for more info on GBAS. It gives a good description of how the approach path is defined. For GBAS it is uplinked to the aircraft from the ground station.

The aircraft derives a differentially corrected 3D GPS position so both lateral and vertical position is provided by the GBAS. Typically the GBAS receiver and processing equipment will be contained within an MMR with guidance outputs to the autopilot/flight director. The GBAS approach can be selected through the FMS or through a separate control head, just like selecting an ILS approach.

If you need more info try Googling "GBAS" or "LAAS".

Cheers, NM.

Thank you for that.

I did that and Wikied it too. :)

Now I know all about USA's WAAS (Wide Area Augmentation System) and LAAS (Local Area Augmentation System) and Australia's GBAS (Ground Based Augmentation) and GRAS (Ground based Regional Augmentation System.)
Japan and Europe are also developing their own systems. Fantastic stuff!

Wikipedia WAAS: http://en.wikipedia.org/wiki/WAAS
Wikipedia LAAS: http://en.wikipedia.org/wiki/Local_A...ntation_System

http://www.airservicesaustralia.com/...S_brochure.pdf