Navigation & GPS

[Ikos]

Hello gentleman,

If you could possible answer my question. In modern day aviation and aircrafts is GPS used or its more up to Flight Management Computer to create a flight path from A to B. Or maybe its the navigation map which is used, for example from VOR to VOR? I have been in the Airbus 319-320 cockpit and didn't notice GPS 'screen'.

Sorry for bothering,
thanks in advance.

[clicker]

As far as I'm aware FMC's are the main source for navigation. although they can use GPS information to cross check the location the FMC can also use VOR's and NDB's for the same purpose.

I also believe that in the case of any information not getting though it can run on its own until the cross checking kicks in again whereby if a GPS is unable to get a good fix because of the poor satellite reception it gets downgraded to a point when its too inacurrate.

The GPS standard has improved over the years but still I've seen the error go haywire when the satelittes are on the horizion or grouped to close together.

However will say I'm not aircrew and this answer is just based on what I'v learnt myself.

[Barnaby the Bear]

http://en.wikipedia.org/wiki/Inertial_navigationEvery stand at an airport will have the exact lat long position. The crew will put this into the FMS. Using Inertial navigation System (INS (Gyros etc):8 ) the FMS will know exactly where the aircraft is at anyone time.
VOR's, NDB's and other exact repoting points such as a published Distance on a specific radial from a VOR; will be entered into the FMS along the route.
GPS trials are still on-going, but as far as I am aware it is still controlled by the US. Therefore in theory can be switched off by them.
I am probably out of date, so pilots would be best suited to answer.

[Intruder]

In most airliners, INS is the primary navigator. In most modern airliners the INS position information is fed to the FMS, which then feeds the displays, flight directors, autopilot, etc.

The INS and/or the FMS can be updated by GPS or some combination of VOR/LOC/DME. When updated continuously by GPS, the GPS in effect becomes the primary navigator.

You do not see a "GPS screen" because all it does is feed information to the FMS; the GPS may or may not have an On/Off switch, or a means of inhibiting its input to the FMS. The FMS and its CDU (Control Display Unit) is the primary navigation interface for the Pilots.