GPS arc.
 

Just a query I have from other IFR jockies. Can a DME arc be done by an approved TSO'd GPS, assuming pilot endorsed on GPS, current data card. Everyone seems to have a differnt idea. Only publication relates to it is CAO 40.2.1, page 21 under flight tollerances?????? <img src="confused.gif" border="0">

Refer to AIP (ENR 1.5.2.1)

Use of Navigation Aids. ..... Only the navigation aid, or aids, identified on each instrument approach chart may be used to fly the procedure....

The answer to your question would be NO.

Cheers,. .Capt EFIS.

Yes the answer is No. <img src="rolleyes.gif" border="0">

Yep you sure can.....if you are inbound to an azimuth nav aid {ndb, vor etc,}and above the lsalt for that sector or outside of the final approach fix if your doing a gps arrival you can circle or arc to your hearts content.....

Hope that helps.

Yes, for manouvering prior to the final approach fix on a dme/gps arrival. You can not however place the aircraft at a fix based usually on an azimuth aid plus dme input using gps for the dme distance. ie: you can not fly a vor/dme approach with a TSO'd gps in place of a dme. Not even the arc after the initial approach fix.

Query arose because I just did my IFR renewal last week, and that arose. Every pilot had a different opinion, as everyone knows that you can do a GPS arrival, however descending to the DME arc steps using the GPS? Thanks fellas, I will put everyone straight now.. .Eg Darwin 11 Locator approach. 12 DME arc.. .Even an ATO in Darwin says you can using the GPS.

[ 26 February 2002: Message edited by: G.A. Boy ]</p>

G.A. Boy, the Darwin RWY 11 Locator or Locator / DME clearly states what Aids you can use. I agree with Cpt EFIS. Perhaps the ATO needs "edumacating".

I think the answer would be yes. However you would need to back it up with a DME readout to be legal, kinda defeats the purpose. <img src="smile.gif" border="0">

[ 28 February 2002: Message edited by: Sopwith Pup ]</p>

I don't know the approach to which you refer but DME arcs conventionally commence at an IAF. Here's where it gets a bit complex. If the lowest altitude available on the arc is below the MSA you might have to remain at the MSA until turning off the arc. Of course, if there happens to be a DME fix for step down after leaving the arc, you must - at present - use DME, not GPS, so the whole idea of using GPS in he approach becomes a bit pointless.

As a slight modification to the above, however, if the arc - or the portion of it that you need to use - is contained within the step of a sector DME/GPS Arrival, you can maneouvre as if still using the Arrival. But, from there on, further descent can only be on the basis of a DME/GPS Arrival. Now, if that brings you down to circling MDA, I'd have to say it would be more efficient to come straight in on the arrival.

If you need the straight-in MDA, any descent steps involved can only be used by reference to DME. So, all in all, I'd have to say that the answer to your question is no, even if only for purely practical considerations.

No. CAPT EFIS hit it on the head.

We are confusing the question. Of course you can GPS arc above applicable LSALT or in manouevring sector. You can do what ever manouevres you like above the LSALT - lets not limit it to GPS arcing!!

BUT, I think you are asking about manouevres below LSALT on a published approach, ie a VOR/DME. The answer is an obvious NO. GPS is not a DME. They even tell you which approaches you can use GPS simply by the way they are named - GPS Arrivals. GPS/NPA. Its easy when you look at it that way.

The ATO may have misunderstood the question (I hope).

<img src="cool.gif" border="0">

Excuse me Helmet Fire, but don't you think the MSA is what you should be refering to and not the LSALT with regards to manouevring to the degree that is being suggested.

Too right Bob. Didnt want to get bogged down in the millions of definitive terms, sorry.