Hey guys, I haven't heard of this before but I was taking an FAA course and it mentioned that airline pilots will back up their GPS/VOR navagation means by "Flying Green Data" which says that its basically a form a dead reckoning in the event of failure of the nav systems... By knowing your heading, altitude and distance to the next fix.

Flying the Green Data? I have never heard of this... You guys do this often? Would somebody elaborate? Is this just an airline version of pilotage and dead reckoning?

Why is it called "Green Data"?

Just means that the non flying pilot is manually tuning in the VOR freqs associated with the V/J airway. the OBS needles are green, magenta when using the FMS for navigation. (in the embraer)

Its flying in the Green World and the Magenta world. Green is conventional nav and magenta is FMS.

FMS is white needles in the CRJ. Raw nav data is green.

It could also be magenta if you're using the FMS bearing pointer.

Yeah, come to think of it they where white in 1900 too.

I would think this to be impossible if the FMS system is utilizing the "Auto Tune" feature.

K, so what the heck does "flying green data" mean? Is it just raw nav stuff?

Exactly...just like in a GA airplane. You manually tune the radio, twist in a course, and you are presented with a virtual RMI on the PFD (Primary Flight Display on a CRT or LCD screen). You may have to ID it the old-fashioned way, or the station ID may be presented in text format on the PFD (usually if the station has an associated DME).

The GS is presented on one side of the PFD.

Normally you fly white needles (or magaenta or whatever color depending on the airplane) which means the FMS auto-tunes whatever navaids it wants and utilizes the data it recieves to track a pre-programmed route. It also uses GPS so if either GPS or VOR/DME was unavailable hopefully you would have a backup. The FMS is normally coupled to the AP.

In the Gulfstream one pilot flies "blue" (FMS) while the other one flies "green" (NAVAIDS- VOR/ILS, etc). If RAIM goes bad, or FMS doesn't switch over to approach mode (0.3 RNP), then you can't fly an FMS approach. Having the co-pilot in "green" lets you continue the approach by just handing the jet over to him, while you get your side set up in "green".

The Honeywell FMS's that Gulfstream uses look for GPS first, then DME/DME, VOR/DME, and finally inertial nav (IRS). If GPS signal is lost, the FMS will look for multiple DME signals to triangulate.

If you lose GPS overwater and out of range of NAVAIDS, then you are stuck w/IRS's which are good for 6.2 hours before they drift too far out of tolerances.