747-400 GSP/NPA Possible?

[mrdaz]

I was wondering is it possible to carry out a GPS Non Precision Approach (I Believe an Australian specific approach) In a 747-400. Also does the 747-400 currently utilize GPS technology and if so how does it relate to the IRS and FMS.

[Zeke]

Dont think why not, it is possible with airbus aircraft.

With airbus the fmgc (airbus fmc) uses the gps to provide position accuracy for fms based approaches. It is a customer option to have them, depending where you are flying it may or may not be advatage, as each fmc has in the order of 5 dmes to get position updates off ground based aids.

Most databases aleady have waypoints associated with ground based and rnav approaches with the required vertical speed, height, distance, flight path angle constraints already coded.

The actual boxes in the aircraft are made by people like honeywell and are fairly generic between aircraft manufacturers.

[QAVION]

"Also does the 747-400 currently utilize GPS technology and if so how does it relate to the IRS and FMS. "

GPS is fairly standard on 747-400's these days, MrDaz. On the latest aircraft, the two GPS antennae mounted on the 747-400's hump feed GPS signals to Multi-Mode Receivers (MMR's) in the Main Equipment Centre. These MMR's send GPS position info to the FMC. Older 400's without Multi-Mode Receivers may be retrofitted with GPS, having small, dedicated receivers in the roof, near the antennae. These receivers feed info directly to the FMC. There may be other installation variations.

Note: Different FMC software/hardware is required for -400's with GPS installed.

The FMC uses the most accurate source of position updating available to it, whether it be GPS, DME, LOC, VOR, IRS, etc... and it can be combinations of these. As far as I know, GPS/GPS/LOC provides the most accurate position fix.

GPS is excellent for long overwater sectors where the aircraft may be out of range of land-based navaids (and the IRSs are slowly drifting).

When the FMC is using GPS for position updating, "GPS" is displayed in the bottom right hand corner of the Navigation Display. Also, when the POS button is pushed on the EFIS control panel, a GPS symbol is displayed on the ND Map.

Rgds.
Q.

[ 28 November 2001: Message edited by: QAVION ]

[mrdaz]

Thanks for the reply QAVION,

That clears allot up.

Just one follow up;

Which airliners you are aware of have these GPS capabilities? And What type of planes. ie.737,767,777,747,A340,A330,A320 etc.. utilze it?

[QAVION]

"Which airliners you are aware of have these GPS capabilities? And What type of planes.
ie.737,767,777,747,A340,A330,A320 etc.. utilze it? "

I generally don't work on Airbuses, MrDaz, but I've seen GPS's on 777's, one or two Classic 747 freighters (as a replacement for INS) and on newer 767's (with Pegasus FMC software). I've also seen GPS fitted not as part of the navigation system, but as part of the Enhanced Ground Proximity Warning System upgrade on older 767's and 747 Classics.

I'd say that the latest 737's also have GPS FMC input (It may even be standard on the 737NG's (?)).

Rgds.
Q.