U

USCANAM

Well Known Member
Did a search on this, but came up a little short.
What I did seem to find that when filing a flight plan I could use "RV9A/?"
In my plane I have an Blue Mountain Sport EFIS, Garmin Mode C Transponder, Garmin G530, etc. The 530 is not WAAS, and as of this date, the database is not up to date.
Can I legally use /G or do I use /A?
Thanks
Jack
RV9A
Getting ready to fly to Sun n Fun.
 
My conservative sense says that you can't file /G without an "IFR legal" GPS, and since you don't have a current database, the GPS isn't IFR legal....

Paul
 
Also, officially it's RV9 (not RV9A)... they don't seem to care where the third wheel is located :)
 
DB currency...

As long as you have determined that the info in your database is still valid for the routes and approaches for your flight (that's the tough part), then you are good for /G. (I've read that, but don't ask me where...)
When in doubt, file /A and note in the comments that you have GPS on board. This is true whether or not you have WAAS.
 
roee said:
If I'm not mistaken, /A denotes that you have DME. If you don't have DME, I think you're a /U.
Click to expand...
Roee
I guess we get into reading between the lines, but isn't a GPS as good, or not better than an old DME unit.
Jack
 
Jack,

A GPS is probably for all intents and purposes BETTER than a DME.

Fact O' the matter is it ISN'T DME soooo, you are better off going slash Uniform for accuracy sake in my opinion.

(FWIW)

:) CJ
 
Looks from this table (from http://www.faa.gov/airports_airtraffic/air_traffic/publications/atpubs/AIM/Chap5/aim0501.html) that /A (with DME) and /U (without DME) would be correct (assuming no IFR GPS on board).

Same thought ocurred to me on GPS distance readouts as you had Jack...though, like others said, I'm confident it's considered a different animal than DME. Gotta figure that if you're /A, you're legal for an ILS/DME, LOC/DME, etc. approach (one with DME in the approach name), and if you're /U, you're not (and the non-IFR GPS with the mileage readout is just providing SA, not providing any legality for an approach).

Here's the table (which didn't paste well):

Aircraft Suffixes

Suffix Equipment Capability

NO DME

/X No transponder
/T Transponder with no Mode C
/U Transponder with Mode C

DME

/D No transponder
/B Transponder with no Mode C
/A Transponder with Mode C

TACAN ONLY

/M No transponder
/N Transponder with no Mode C
/P Transponder with Mode C

AREA NAVIGATION (RNAV)

/Y LORAN, VOR/DME, or INS with no transponder
/C LORAN, VOR/DME, or INS, transponder with no Mode C
/I LORAN, VOR/DME, or INS, transponder with Mode C

ADVANCED RNAV WITH TRANSPONDER AND MODE C (If an aircraft is
unable to operate with a transponder and/or Mode C, it will revert to
the appropriate code listed above under Area Navigation.)

/E Flight Management System (FMS) with DME/DME and IRU position
updating
/F FMS with DME/DME position updating
/G Global Navigation Satellite System (GNSS), including GPS or Wide Area
Augmentation System (WAAS), with en route and terminal capability.
/R Required Navigational Performance (RNP). The aircraft meets the RNP
type prescribed for the route segment(s), route(s) and/or area
concerned.

Reduced Vertical Separation Minimum (RVSM). Prior to conducting
RVSM operations within the U.S., the operator must obtain
authorization from the FAA or from the responsible authority, as
appropriate.

/J /E with RVSM
/K /F with RVSM
/L /G with RVSM
/Q /R with RVSM
/W RVSM


Cheers,
Bob
 
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DME vs. GPS

USCANAM said:
Roee
I guess we get into reading between the lines, but isn't a GPS as good, or not better than an old DME unit.
Jack
Click to expand...

From the controllers perspective, the accuracy isn't the point. DME has a slant range factor and the DME ground unit may be located with an ILS system, vortac, or ??. GPS is calculated differently. 10 DME east of XYZ is not the same as 10 miles GPS east of the airport. The DME may not even be located on the airport proper. The controller will compare two DME distances off the same point and will separate two DME equipped aircraft from each other based upon that report. If you state a GPS position in place of a DME distance or substitute the GPS position when you have filed as a /A you are giving a different report than you were asked to give. You will not be separated from the other airplane, at least, not intentionally. How do I know this? I spent 30 years in ATC although I have been retired for the past 10 years. DME rules, I am sure, have not changed during that time but are actually used less often today since radar procedures replace the need for DME and VOR radials in recent times. Radar is the preferred method of separation but that is not always possible so DME and VOR radials are still around.

Do not confuse the two as it MAY make a difference and the pilot will not realize it. We used to encourage pilots with no DME or an IFR GPS to file /U and then in remarks put " VFR GPS equipped". I hope this helps.

Dick DeCramer
N500DD RV6 300 hours
RV8 Fuselage
Northfield, MN
 
USCANAM said:
Roee
I guess we get into reading between the lines, but isn't a GPS as good, or not better than an old DME unit.
Jack
Click to expand...

Jack,

DME is different than GPS in that it provides slant distance, not ground distance, as others have noted.

But besides that, indeed, I believe there are instances where a GPS may legally be used instead of DME to establish a fix, but of course the GPS again has to be certified and current. So it's sort of a moot point. If it is certified and current, you're /G. If not, then it's not legal as a DME substitute either, so you're back to /U.

-Roee
 
Great Responses

Thanks all.
Seems to me the best way to go as suggested is the /U, then in Remarks, put VFR GPS. That way the controllers (if they are aware of the Remarks notation) know exactly how to handle you.
I'm sure I'm not the only RV out there having the same questions. This should help
Thanks
Jack
Say Hello at S n F !!
 
While the distances can be significantly different at short distances and almost the same at large distances, they are not the same even if measured from the same point. DME is a slant distance while GPS is the distance measured along the ground from the point to directly below the GPS receiver.

If you are at 12,000ft and directly over the DME station, what would your DME read and your GPS read? Your DME would read 2 nm and your GPS would read 0 miles.
 
GPS subs for DME

Per AIM 1-2-3 a(1), an IFR GPS is a valid substitute for DME, so /A is a valid choice. Even though the database may not be current, it still calculates distances. No need to split the hairs that fine :rolleyes: ATC wants to know your capabilities, and you have DME capability :cool:
 
Dick:
AC 91-2 was issued a couple of years ago and describes the allowed use of GPS as an alternative or replacement for DME. Regarding the original question posted, if the GPS is not current (legal) then it cannot be used as a replacement for DME, hence the need to use /U as the equipment suffix. Here's a question that I'm not sure of - If a certified GPS is not current, can it/should it be entered on the form as a VFR GPS, as each of these units are governed by different TSOs.
Terry, CFI
RV9A N323TP
 
To open another can of worms here...

If your GPS database is not current, and you use it for navigation of any kind (substitute for DME, etc.), even in VFR conditions, isn't that the same as using expired charts (a no-no)?
 
Wow lots of stuff discussed.

If you can validate that a given point hasn't moved since your database was updated than you ARE good for IFR ENROUTE and TERMINAL operations... if you have a UPSAT GX, SL or Garmin GNS480 that is... That is the way UPSAT certified them. That said, when was the last time a VOR was moved? So if you fly with a GX60, SL30 combo IFR like I do, you can use the DST feature for DME all time time. Garmin GNSx30 units require current databases IIRC.

Most controllers aren't gonna be able to see the remarks section of your flight plan. When a control strip comes through, it don't include that information, so most of us won't know... I don't know how THAT little rumor got started.

VFR GPS are for reference only, the features of the device are not intended for primary navigation at any point... thats why you need a chart. There are no expiration dates on VFR gps databases... therefore they are never current or not.

Controllers don't often note the difference between DME and GPS distances, because we mostly have radar, and if you give us a position within a mile or two we'll be able to figure it out from there...

My suggestion:

If you are flying VFR, file /G. That will show up on the flight strip, so the controller will see it.

If you are flying IFR, file what you are able to legally use, and comfortable using. If you are all current databases, but don't know how to use the IFR capability of the GPS, DON'T file /G...
 
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