RNAV and the glideslope

[Percula747 0]

Hey everyone,

 

when I enter an RNV approach into my 747's fmc, it seems to not stay on the glideslope..?!?!

 

How does altitude management work for rnv appoaches?

 

Greetings,

Jannis

[pschlute 37]

I am no expert, but I thought the object of an RNAV approach was to get you decision altitude without the use of the glideslope?  If you are using the LOC and Glideslope, that is an ILS approach.

 

What airport/runway are we talking about here?

 

Peter

[Chrjs 61]

Theres is no "Glideslope" on a RNAV Approach. The FMC, however, calculates a "Glidepath" to meet the altitude constraints.

[Percula747 0]

Okay, thanks!

So during the whole approach you remain in lnav and vnav mode??

[pschlute 37]

Okay, thanks!

So during the whole approach you remain in lnav and vnav mode??

I have just flown RNAV approach into Munich 26L

 

As I was flying in LNAV/VNAV the minima is 1900. So I fly in those modes until 1900 feet ( or whatever your runway DA is). Then, if you can see the runway, you turn off the autopilot and land the aircraft. So the correct answer is... you fly the approach to minimums in LNAV/VNAV.

 

Peter

[Eric_Parker 4]

Correct Percula747. RNAV approaches are designed to get you to your destination at an altitude from which you can land. The autopilot will not land the airplane unless it is coupled to the ILS. Localizer approaches do a better job fo finding the runway than RNAV/GPS approaches but only full ILS approaches will get you down correctly.