NVFR GPS/NPA arrivals?

[SpottyFish]

NVFR GPS/DME arrivals?

Came back to base tonight just after last light (15mins) and conducted the standed NVFR arrival.

This involved trying to lose over 2000ft from route LSALT to circuit height and coupled with a tailwind made the whole process, in my opinion, impractical.

Those with instrument ratings know that when within 25nm or 10nm the relevant LSALT usually reduces making the process of joining the circuit less painful. Of course these LSALT are only relevant when used with either GPS or DME.

Also GPS/DME arrivals ensure terrain clearance throughout and are used often to position an aircraft to join the circuit, even when VFR day or night.

Why not have an approach plate made up for VFR ops and VFR pilots, coupled with a DME or GPS w/current data card and pilot enroute endorsement, which would allow descent to circuit height.

The plate would be designed to bring the aicraft down to circuit height within 3nm.

I know of numerous companies and private pilots that would not only benift from this but would also improve safety through reduced circling and a more standed circuit entry.

The key points for this to work are:
1.Approved proceedure designed for VFR pilots
2.GPS enroute training as part of NVFR rating
3.TSO GPS with current data card
4.Arrival proceedure would not allow descent below circuit height

Any thoughts??

[AerocatS2A]

IMO NVFR is already too close to being IFR. If you need to be doing a GPS or DME arrival to get to where you're going, then perhaps you should be flying IFR.

If you need to lose 2000\', what is so troubling about losing 1000\' from 3nm out to arrive over head at 2000\', then join a wide upwind losing 500\', turn onto crosswind, lose another 500\', now you\'re down to circuit height on downwind.

[SpottyFish]

I Understand what your saying, but when you pass your NVFR flight test, you end up with approval to use NDB/VOR for Azimuth guidence, why not provide the Pilot with the increased safety margin of vertical guidence? And who says you would NEED to conduct a DME/GPS arrival to get where your going? We are talking NVFR here which means VFR conditions so there shoud be Know problems in getting where your going, if you had planned your flight properly.

All im suggesting is something to increase the safety margin (i.e less circling overhead may decrease the risk of know disorientation associated with flying at night - Leens etc)

Not every Pvt Pilot has 10K for an instrument rating

[AerocatS2A]

Fair point. It would make sense to be able to use the 25nm and 10/15nm MSA and its not much of step from there to doing a DME/GPS arrival.

Can you not work out your own LSALT for the final route segment, in accordance with AIP, which is lower than the published LSALT (which may have a longer route segment length and therefore be based on terrain that you are nowhere near?)

I have never done a NVFR so I'm unsure as to what you and can't do.

[SpottyFish]

what your saying is true, However lets say you are inbound to Broome from south (although no terrain here, this is just an example), there is nothing to fix your position on to recalculate your lowest safe. There is however an NDB which the NVFR pilot is already endorsed on and also a DME which the pilot could use in the situation i proposing if they were adequetly trained.

Just remember, there may be plenty of positions to fix yourself on in city areas, but in most country towns the isn't and the strip is usually located some distance from the town (and may not be located on track) making it nice and dark

[Tinstaafl]

A NVFR pilot is already appoved to use the DME to obtain a fix. The ADF/VOR endorsement is to do with the complexities of orientation, inteception & tracking inherent in those aids.

Even VFR only and Instrument Rated pilots without a DME/GPS endorsement is allowed to use a DME to obtain a circular position line to contibute to a position fixing requirement eg two position lines etc.

There's nothing preventing a NVFR pilot from using a DME + a visual position line or a radio position line to fix the aircraft's position. The only catch is that the position lines must cross at no less than 45 deg.

An advantage of using a visual pinpoint for a NVFR fix is that it allows a descent immediately the limiting obstacle is passed. Any other position fix must have at least a 10nm buffer after the critical obstacle before descending

[JSM]

I think you might be onto something Spottyfish, i know what Tinstaafl is saying and i agree but some where like Gibb River Narrogin, or Margaret River etc where there is no DME would benefit from what your proposing.

A plate designed for Pvt pilots or Commercial pilots without PVT IFR or MECIR, that would alow them to use the 25/10nm MSA, coupled with an approved decent profile would be awesome. One of the biggest safety features i believe would be the fact that LSALTS would be ones that have already been approved and proven, as opposed to releying on ONE'S LINE DRAWING ABILITY, and then making sure you have picked the highest feature etc etc

The whole procedure is done in VMC obviosly, and i guess if it all went pear shaped you could maintain the last safe level and track to the field

My 2 cents worth

[UnderneathTheRadar]

DME Approval

Tinstaafl

I'm not sure that a NVFR pilot is authorised to use DME unless they have been specifically trained in it's use - I could quote from a CAO if I could be bothered finding it..... My logbook allows me to use NDB & VOR and the examiner left space to write GPS once I do the ground school required. I did ask about DME and his response was a) there are very few DME left (Broome being one obviously) and b) do the GPS course and use that instead.

Once I've done the GPS course then I don't see any reason why I can't use the relevant charts to get the 25 or 10 LSALTs and descend as required (unless I've misunderstood what you can use GPS for - that's why I'm waiting for the course!)

UTR.

[AerocatS2A]

That's odd. There are DME all over the place. There aren't that many sole DMEs I suppose, but most VORs around the country seem to have a co-located DME.

[150Aerobat]

Spottyfish,

I hear what you are saying, but don't you just do the PIFR? All the trouble you mention, namely,

1.Approved proceedure designed for VFR pilots
2.GPS enroute training as part of NVFR rating
3.TSO GPS with current data card
4.Arrival proceedure would not allow descent below circuit height

with all that kit and training, you'd be 2/3 of the way to the PIFR anyway.

Aerocat

There are DME all over the place

um .. not really.

[swh]

The following applies to NVFR only.

AIP GEN 3.8 allows for the use of GPS for track guidance to reduce the area for LSALT calculation, 10.3 degrees out to 7 nm either side of track to a 7nm ring around the destination.

Many GPS receivers can be setup to calculate a Grid LSALT based upon the Jepp Grid MORA in the database 7nm either side track from present position to any enroute position or destination.

AIP GEN 3.11 only allows flight below the calculated LSALT by
During takeoff and climb
Destination in sight, and within 3nm
When being radar vectored.

However if a pilot has visually passed a critical obstacle they may descend to a new LSALT once passed that critical obstacle visually (AIP GEN 3.8)

The AIP does not allow for a NVFR pilot to descend using GPS/DME arrival or NPA, that is for IFR only, refer AIP GEN 3.10.

[JSM]

I understand that the GPS/DME arrival is for the IFR, but i think what spottyfish is trying to say is that there should be a VFR specific GPS/DME arrival "INVENTED" i would suggest that the plate would look almost identical to the IFR plate but have things like "missed approach procedure" etc ommited, and as said eariler, the arrival procedure would not allow descent below circuit height

all i think is that with such improvments in technology - GPS, glass cockpits in light GA aircraft etc surley new procedures can be invented to help increase safety margins.

[AerocatS2A]

um .. not really

um... well I wouldn't say that "there were very few left", just off the top of my head, down the saparsely populated west coast, there are DME at CIN, BRM, PD, KA, LM, CAR, GEL, and PH.

I guess we have different views on "all over the place".

[OzExpat]

Here's an (old) idea...

I did Night VFR when it was called Night VMC and required a Class 4 Instrument Rating. That dates me a bit and there were certainly not the large number of improvements that are available now. However, when planning a night flight, I would :-

1. Take hold of map;
2. Plot lat/long of any available DME;
3. Draw in the enroute tolerence area (using platic overlay and chinograph pencil... remember those things?
4. Find all the big rocky bits and work out an appropriate DME distance to allow descent beyond them and draw in the respective DME arcs.

I always allowed 3 NM for DME error (the old Domestic DME standard within 30 NM) and 1 NM for safety. The resultant DME distance is what I used to structure my descent. Was also handy on departure into a really inky black night (yeah, yeah, I know...), as I would then always know how I had to manoeuvre safely during the climb.

The first few times I did it, it took quite a while to work out, but got quicker as I gained familiarity with the map work.

You've got it even easier today with GPS - provided that you can trust it to perform properly - as you only need to plot the position of the destination ARP to have a distance reference. So why not do all the hard work yourself?

[Wheeler]

DME's might be working now but most approaches, even ILS, now allow approved GPS to be substituted for DME. One wonders how long Airservices will keep maintaining those expensive DME's - and VOR's and NDB's for that matter.

[OzExpat]

Perhaps for quite a while yet Wheeler. I heard, some months ago, that AsA has embarked on a major program of navaid replacement. If this is true, probably says something about their attitude to GPS - and GNSS as a whole.