Double NAV

[kaiallard]

What's with the NAV 1 and 2. Why is there two NAVs? on boeing jets this means a total of four NAVs (active and standby). What is the significance of so many NAVs? I mean, the boeing jet will only need one of the NAV to land right?


http://www.flightsim.com/dcforum/Use...417064b33a.jpg

I am so sorry but cheers anyway.

[leffepojken]

There are many reasons two is better than one. Say you're about go around and have to execute the missed approach procedure. The last thing you want to do is to start tuning the radios.

Experts.. step forward!

[chasw]

Two navs are needed to be able to crossfix a position via VOR signals. Not all VOR's have DME. You might also need two navs if one decides to go on the fritz halfway through a 4,000 mile flight, as its a bit tricky to step out and buy another or get an engineer in. You might also need two navs to do a VOR approach with the correct turning points at night, in bad weather, with 240 extremely tired passengers sitting behind you all hoping to make their connections and not get diverted 200 miles to an airport they dont want to go to. You might also need two navs to be able to set the next waypoint while still flying toward another. Im sure there are other good reasons too but Im so bunged up with the `flu I cant think of any right now.

Chas

[flyinggriffin]

The reason for active and standby frequency on a nav or com for that matter is so that you can setup your next frequency at a time when the workload is not painfully high. The less things you have to do under pressure, the less chance there is for a screwup.

Two navs can be used to check the accuracy of the system. In the real world, things break, get out of calibration and just plain don't fail as neatly as they do in flight sims. More than likely if an ILS isn't available the crew will be shooting a VOR/GPS approach with the GPS but you can bet they are backing up the GPS with their navs.