Approaches

Terry

Terry

Line Up and Wait
Joined
Apr 3, 2005
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Terry
Hi All:

If I have VOR/DME can I use a RNAV approach ?

Also it appears that ALL RNAV are also GPS's but NOT all GPS's are RNAV.

Here's what I am getting at. RNAV, area navigation, was around before GPS. Correct?

Why then aren't there any RNAV only approaches?

What do I need to fly a RNAV approach? (Physical Equipment)

Terry :dunno:

If ATC is my eyes and ears when I get my IFR approval I hope they ALL have 20/20 vision and excellent hearing. :D (Hope my controller isn't named Magoo)
 
Terry said:
Hi All:

If I have VOR/DME can I use a RNAV approach ?
Click to expand...

No. There is a separate box (computer) which takes VOR and DME signal, messages the input, and then sends an altered output to the DME display and the VOR indicator. Without that box you may not legally fly IFR RNAV (VOR/DME).

Also it appears that ALL RNAV are also GPS's but NOT all GPS's are RNAV.
Click to expand...

Sometimes. RNAV (GPS) and RNAV (VOR/DME) sometimes appear as "OR", which means an overlay, but they also appear as separate and unique items.

Here's what I am getting at. RNAV, area navigation, was around before GPS. Correct?
Click to expand...

Yes. Originally "RNAV" referred to a VOR/DME version of random area navigation. Not it means any type of random area navigation.

Why then aren't there any RNAV only approaches?
Click to expand...

They exist. An example is the IGX VOR/DME RNAV RWY 9 (Chapel Hill, NC). However, due to the overwhelming desire of Jeppesen and the GPS box providers to lock folks into a database update service, and the historically poor acceptance of VOR/DME RNAV (I have an IFR certified unit in the Mooney), not to mention AOPA's failure to take any notice or exception to folks like me with existing equipment being orphaned, the VOR/DME RNAV approaches are rapidly disappearing.

What do I need to fly a RNAV approach? (Physical Equipment)
Click to expand...

VOR, DME, and an IFR approved installation RNAV box. An example is the KN74 (my Mooney). More common is the KN84 (larger, but some added features).
 
Terry said:
Hi All:

If I have VOR/DME can I use a RNAV approach ?
Click to expand...

If your question is about flying an RNAV approach with just a VOR and DME the answer is no.


Also it appears that ALL RNAV are also GPS's but NOT all GPS's are RNAV.
Click to expand...

Not true. Check out the VOR/DME RNAV RWY 27 approach to KEVM. This cannot be legally flown with GPS.

Here's what I am getting at. RNAV, area navigation, was around before GPS. Correct?
Click to expand...

Yes.


Why then aren't there any RNAV only approaches?

What do I need to fly a RNAV approach? (Physical Equipment)
Click to expand...

There are two kinds of RNAV systems. The earlier system based on VOR's with DME is called Rho-Theta which is (sort of) Latin for distance-angle. The King KNS-80/81 is an example of such a system. It computes the aircraft's position relative to a waypoint which is defined by a radial and distance from a nearby VOR. This is what's required to fly a VOR/DME RNAV approach that doesn't have "or GPS" in the title.

The newer RNAV approaches are intended to be flown by independent Nav systems like GPS that meet a specified performance requirement like RNP 0.3.
 
I think they have to say "GPS" in the title if you want to do an 'RNAV' approach with a GPS. Ie GPS (RNAV) RWY 33 Looking for corrections if I have it wrong; that's how it was taught to me.
 
Dave:

I can't view your link.

Terry
 
Here's a little bit of a twist that I ran across today...

A couple of approaches at Moberly, MO (MBY) are "VOR/DME RNAV or GPS" approaches, so the useable non-GPS navigation system is RNAV based on VOR/DME.

Fly safe!

David
 
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