substituting Garmin 430W for DME, ADF

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shenanigans

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I know I can use an approved GPS as a substitute for ADF and DME to identify fixes on an approach. For example, a VOR approach with a note "DME required" and the FAF is identified by a DME distance. But how is that done with the 430W? Do I just load the approach in the 430W as normal (which gives a warning) and use the waypoints sequenced on the approach to know when I've passed the DME position?

Also, is this allowed on an approach that has DME listed in the procedure name (VOR/DME or LOC/DME instead of just VOR or LOC)? I read it wasn't but the reference cited as out of date and I can't find anything similar.
 
You can load the approach, but you can also select direct to the VOR or ILS identifier which will give you the distance to the station. Yes, it is allowed for a VOR/DME or ILS/DME if the GPS database is current. I can't recall a specific reference, but that's what the DPE told me during my IR oral.
 
Any fix that is necessary for the approach will be loaded and sequenced as part of the approach. So, if the FAF is at 6.5 DME, there will be a fix there in the 430W and it will sequence to it as part of the approach (giving you a countdown for the distance to it).

As I understand it, the only thing that you can NOT do is use the GPS as the primary means of lateral guidance past the FAF on an approach that is not an RNAV/GPS approach.

Take, for instance, the VOR/DME RWY 23 at KDSM. EXPEN and DIPPO will be loaded into the 430w as waypoints in the approch. You can use the GPS as the primary means of flying the approach (including having the CDI set to "GPS") until you pass DIPPO inbound. After that point, you must have the CDI set to "VLOC" and be navigating off of the VOR signal for lateral guidance. Though, you can obviously still identify the MAP (which is at 28.5 DME) with the GPS.
 
Thanks for the fast responses. That's pretty much what I figured, but I was thrown off by the warning it gave when loading a non gps approach and wanted to double check that I was doing things right. Appreciate the confirmation.
 
FlyNE said:
Any fix that is necessary for the approach will be loaded and sequenced as part of the approach. So, if the FAF is at 6.5 DME, there will be a fix there in the 430W and it will sequence to it as part of the approach (giving you a countdown for the distance to it).
Click to expand...

This is very important. The GPS will give you Along Track Distance (ATD) which decreases as you get closer to the active waypoint. DME on the other hand, can increase or decrease depending where the DME antenna is located. I have found a handful of students who confuse the DME distance published on the approach with the ATD given by the GPS or vice versa. Just a quite note I thought was worth mentioning.
 
HPNPilot1200 said:
This is very important. The GPS will give you Along Track Distance (ATD) which decreases as you get closer to the active waypoint. DME on the other hand, can increase or decrease depending where the DME antenna is located. I have found a handful of students who confuse the DME distance published on the approach with the ATD given by the GPS or vice versa. Just a quite note I thought was worth mentioning.
Click to expand...

That's a great point. The approach that I referenced in my example would work that way. Using DME you would be flying away from the station when inbound, so the distance would be increasing up to the MAP (at 28.5 DME). Using the 430 it would show you the ATD as a decreasing number, hitting zero at the MAP.
 
Fearless Tower said:
You can load the approach, but you can also select direct to the VOR or ILS identifier which will give you the distance to the station. Yes, it is allowed for a VOR/DME or ILS/DME if the GPS database is current. I can't recall a specific reference, but that's what the DPE told me during my IR oral.
Click to expand...

Database currency is required or you must verify that the waypoints used in the expired database are still current. You can also fly a GPS approach with an expired database, but you must verify that the approach data in the database is still current. See the current AIM, table 1-1-6, note 3. It has been changed recently.
 
FlyNE said:
Any fix that is necessary for the approach will be loaded and sequenced as part of the approach. So, if the FAF is at 6.5 DME, there will be a fix there in the 430W and it will sequence to it as part of the approach (giving you a countdown for the distance to it).
Click to expand...
As you said, all the waypoints necessary for the approach should be included in the DB but I've seen some instances where one or more useful WPs are omitted, typically ones for stepdowns on non precision approaches. You can still identify the missing fix with GPS but that's likely to require some mental math as the GPS will likely be showing the distance to the next WP in it's sequence rather than the one which the approach distances are measured from with DME.
 
see attached
 

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John Collins said:
Database currency is required or you must verify that the waypoints used in the expired database are still current. You can also fly a GPS approach with an expired database, but you must verify that the approach data in the database is still current. See the current AIM, table 1-1-6, note 3. It has been changed recently.
Click to expand...

Depends on the GPS and the AFM supplement. Some you can do the verify, some you cannot.
 
John Collins said:
Database currency is required or you must verify that the waypoints used in the expired database are still current. You can also fly a GPS approach with an expired database, but you must verify that the approach data in the database is still current. See the current AIM, table 1-1-6, note 3. It has been changed recently.
Click to expand...

Yeah...good luck with that. If you are able to actually verify every waypoint is still current then you might as well update the bloody thing - heck of alot easier.
 
Fearless Tower said:
Yeah...good luck with that. If you are able to actually verify every waypoint is still current then you might as well update the bloody thing - heck of alot easier.
Click to expand...
To fly the approach you only need to confirm that the DB is at least as new as the most recent procedural change which is printed on your current chart.
 
taters said:
see attached
Click to expand...

I've researched this a bit more, and what I've seen doesn't seem to line up with what you've posted. I haven't found anything that says that you can't use a GPS in lieu of a localizer before the final segment. Do you know if they received an actual interpretation letter on this and from who?
 
Fearless Tower said:
Yeah...good luck with that. If you are able to actually verify every waypoint is still current then you might as well update the bloody thing - heck of alot easier.
Click to expand...

Heh, technically you could "update" TO a database with errors that could kill you too.

You can't win with databases. Garbage In - Garbage Out. ;)
 
wsuffa said:
Depends on the GPS and the AFM supplement. Some you can do the verify, some you cannot.
Click to expand...

Very true. However, if the AFMS does not permit use of an expired database for approaches, one can update the wording in the AFMS to permit the operation and obtain FAA approval thru the field approval process. I know of several individuals who have done this. Justification for the change is the current AIM and the already approved wording on several GPS units.

Example of AFMS wording used in the GNS 430 that requires a current database:

"Instrument approach navigation predicated upon the GNS 430’s GPS Receiver must be accomplished in accordance with approved instrument approach procedures that are retrieved from the GPS equipment data base. The GPS equipment database must incorporate the current update cycle."

The wording in the AFMS for the GNS400W series that permits use of the expired database for approaches:

"GPS instrument approaches using the 400W Series units are prohibited,
unless the 400W Series unit’s approach data is verified by the pilot or
crew to be current. Instrument approaches must be accomplished in
accordance with an approved instrument approach procedure that is​
loaded from the 400W Series unit database."

If you have a GNS430, Just substitute the wording to match the 400W series and change occurrences of "400W" to "GNS 430".
 
Fearless Tower said:
Yeah...good luck with that. If you are able to actually verify every waypoint is still current then you might as well update the bloody thing - heck of alot easier.
Click to expand...

I maintain a current database in my aircraft, but there are still times when I may have a down level database (usually one month) in my aircraft and from time to time when flying someone else's airplane, I encounter an expired database.

That said, if one if flying an approach that requires a substitution of the DME, the only thing that needs to be verified is the particular DME lat-long location, which is included on the enroute charts for VORTAC and VOR-DME. Total time to check, about 20 seconds.

If the approach is in the database, then the only thing that needs to be confirmed is that the date on the current chart is the same as or before the database effective date. Approach Charts newer than Oct 2009 have incorporated a procedure amendment date that only changes when the change affects the procedure in the database. This allows older databases to be used when changes that don't affect the database require the chart to be updated. Many instrument pilots are not aware of the new format and what its significance is.
 
I had to re-fly an approach when I went for my instrument rating over something like this. The GPS was a Bendix KLN94. It was a VOR-DME into M01 (no longer publishhed).

You could load the approach, but it wasn't an approved approach, just one available for reference. Approved approaches have a GPS legend in the KLN-94 menus.

So when it came to determining the MAP, the check pilot didn't accept me using the GPS MAP.

To properly fly it with the GPS, I should have just used my VOR for direction and set the GPS direct to the MEM VOR to use distance to identify the MAP.

We all researched it, it boiled down to asking, "was the fix in the approach at the same lat and long as DME whatever on the radial." No way to know when you're flying it anyway.

I think the check pilot was was right. It was not an approved approach, per the KLN-94 manual (lacked the GPS symbol).

My flight instructor dissagreed and we had trained it flying it using the GPS instead of direct for just DME.

Hard to wade through it all in the AIM though.
 
kontiki said:
I had to re-fly an approach when I went for my instrument rating over something like this. The GPS was a Bendix KLN94. It was a VOR-DME into M01 (no longer publishhed).

You could load the approach, but it wasn't an approved approach, just one available for reference. Approved approaches have a GPS legend in the KLN-94 menus.

So when it came to determining the MAP, the check pilot didn't accept me using the GPS MAP.

To properly fly it with the GPS, I should have just used my VOR for direction and set the GPS direct to the MEM VOR to use distance to identify the MAP.

We all researched it, it boiled down to asking, "was the fix in the approach at the same lat and long as DME whatever on the radial." No way to know when you're flying it anyway.

I think the check pilot was was right. It was not an approved approach, per the KLN-94 manual (lacked the GPS symbol).

My flight instructor dissagreed and we had trained it flying it using the GPS instead of direct for just DME.

Hard to wade through it all in the AIM though.
Click to expand...
Your check airman was right. You could use the GPS for the DME but you needed to use the VOR for lateral guidance along the final approach course, if the approach didn't have an approved GPS overlay (in which case you wouldn't have gotten the "advisory only" warning). You could have still loaded the approach, but your CDI must have been set to the VOR and not the GPS.

The reason to load the approach instead of using DIRECT to the fix for DME is that if you went missed you could use the GPS for guidance through the missed approach portion of the procedure.
 
Yeah, but the Garmin 430 pilot's guide forbids the use without a current database...

Can I file slant Golf (‘/G’) using my GPS?

Yes, the pilot may file a flight plan as /G if the GNS 430 is a certified A1 or A2 installation. If flying enroute, the pilot may file /G with an expired database only after having verified all route waypoints. Non-precision approaches may not be flown with an expired database. See an approved Airplane Flight Manual Supplement for more information.
Click to expand...
Ryan
 
TMetzinger said:
Your check airman was right. You could use the GPS for the DME but you needed to use the VOR for lateral guidance along the final approach course, if the approach didn't have an approved GPS overlay (in which case you wouldn't have gotten the "advisory only" warning). You could have still loaded the approach, but your CDI must have been set to the VOR and not the GPS.

The reason to load the approach instead of using DIRECT to the fix for DME is that if you went missed you could use the GPS for guidance through the missed approach portion of the procedure.
Click to expand...

Is it your understanding that you must have it set to the VOR for the entire approach, or only for the final segment?
 
FlyNE said:
That was my understanding as well, but the letter that Clay posted differs from that.

Clay, is that letter from your ops department?
Click to expand...
And the date in 2009 is prior to the latest AIM revision. I believe there was language about localizers in earlier guidance.
 
FlyNE said:
Is it your understanding that you must have it set to the VOR for the entire approach, or only for the final segment?
Click to expand...

Upon further review, the current AIM (03-10-11 version) has a note that prohibits use of the GPS for lateral navigation without reference to the the raw localizer data, so Clay's interpretation is correct. It requires the localizer to be displayed and used for the primary navigation, but in my opinion, using roll steering to direct an autopilot to fly the course would be permitted as long as the CDI/HSI displayed the localizer and it was monitored by the pilot to verify that the aircraft position was within standards.

The section 1-2-3 (c) wording is as follows:

c. Uses of Suitable RNAV Systems.
​
​
​
​
​
Subject to the operating requirements, operators may use a suitable RNAV system in the following ways.
​
1. ​
​
​
​
​
Determine aircraft position relative to, or distance from a VOR (see NOTE 5 below), TACAN, NDB, compass locator, DME fix; or a named fix
defined by a VOR radial, TACAN course, NDB bearing, or compass locator bearing intersecting a VOR or localizer course.​

2.​
​
​
Navigate to or from a VOR, TACAN, NDB, or compass locator.​

3.​
​
​
Hold over a VOR, TACAN, NDB, compass locator, or DME fix.​

4.​
​
​
Fly an arc based upon DME.​

NOTE​
​
−​

1.​
​
​
The allowances described in this section apply even when a facility is identified as required on a procedure (for example, “Note ADF required”).​

2.​
​
​
These operations do not include lateral navigation on localizer−based courses (including localizer back−course guidance) without reference to raw localizer data.​

3.​
​
​
Unless otherwise specified, a suitable RNAV system cannot be used for navigation on procedures that are identified as not authorized (“NA”) without exception by a NOTAM. For example, an operator may not use a RNAV system to navigate on a procedure affected by an expired or
unsatisfactory flight inspection, or a procedure that is based upon a recently decommissioned NAVAID. ​

4.​
​
​
Pilots may not substitute for the NAVAID (for example, a VOR or NDB) providing lateral guidance for the final approach segment. This restriction does not refer to instrument approach procedures with “or GPS” in the title when using GPS or WAAS. These allowances do not apply to procedures that are identified as not authorized (NA) without exception by a NOTAM, as other conditions may still exist and result in a procedure not being available. For example, these allowances do not apply to a procedure associated with an expired or unsatisfactory flight inspection, or is based upon a recently decommissioned NAVAID.​

5.​
​
​
For the purpose of paragraph c, “VOR” includes VOR, VOR/DME, and VORTAC facilities and “compass locator” includes locator outer marker and locator middle marker.​

 
John Collins said:
Upon further review, the current AIM (03-10-11 version) has a note that prohibits use of the GPS for lateral navigation without reference to the the raw localizer data, so Clay's interpretation is correct. It requires the localizer to be displayed and used for the primary navigation, but in my opinion, using roll steering to direct an autopilot to fly the course would be permitted as long as the CDI/HSI displayed the localizer and it was monitored by the pilot to verify that the aircraft position was within standards.

The section 1-2-3 (c) wording is as follows:

c. Uses of Suitable RNAV Systems.
Subject to the operating requirements, operators may use a suitable RNAV system in the following ways.​


1.
Determine aircraft position relative to, or distance from a VOR (see NOTE 5 below), TACAN, NDB, compass locator, DME fix; or a named fix
defined by a VOR radial, TACAN course, NDB bearing, or compass locator bearing intersecting a VOR or localizer course.
​
2. ​

​

Navigate to or from a VOR, TACAN, NDB, or compass locator.
​
3. ​

​

Hold over a VOR, TACAN, NDB, compass locator, or DME fix.
​
4. ​

​

Fly an arc based upon DME.
​
NOTE​

​

−​
​

​
1. ​

​

The allowances described in this section apply even when a facility is identified as required on a procedure (for example, “Note ADF required”).
​
2. ​

​

These operations do not include lateral navigation on localizer−based courses (including localizer back−course guidance) without reference to raw localizer data.
​
3. ​

​

Unless otherwise specified, a suitable RNAV system cannot be used for navigation on procedures that are identified as not authorized (“NA”) without exception by a NOTAM. For example, an operator may not use a RNAV system to navigate on a procedure affected by an expired or
unsatisfactory flight inspection, or a procedure that is based upon a recently decommissioned NAVAID.
​
4. ​

​

Pilots may not substitute for the NAVAID (for example, a VOR or NDB) providing lateral guidance for the final approach segment. This restriction does not refer to instrument approach procedures with “or GPS” in the title when using GPS or WAAS. These allowances do not apply to procedures that are identified as not authorized (NA) without exception by a NOTAM, as other conditions may still exist and result in a procedure not being available. For example, these allowances do not apply to a procedure associated with an expired or unsatisfactory flight inspection, or is based upon a recently decommissioned NAVAID.
​
5. ​

​

For the purpose of paragraph c, “VOR” includes VOR, VOR/DME, and VORTAC facilities and “compass locator” includes locator outer marker and locator middle marker.
​
​
​
Click to expand...



Good catch - I concur. I need to go back and look at the CFI workshop guidance we got from the FAA last quarter because I'm not sure this was brought out clearly enough.
​
 
John Collins said:
Upon further review, the current AIM (03-10-11 version) has a note that prohibits use of the GPS for lateral navigation without reference to the the raw localizer data, so Clay's interpretation is correct. It requires the localizer to be displayed and used for the primary navigation, but in my opinion, using roll steering to direct an autopilot to fly the course would be permitted as long as the CDI/HSI displayed the localizer and it was monitored by the pilot to verify that the aircraft position was within standards.

The section 1-2-3 (c) wording is as follows:

c. Uses of Suitable RNAV Systems.
​
Subject to the operating requirements, operators may use a suitable RNAV system in the following ways.
​
1. ​
Determine aircraft position relative to, or distance from a VOR (see NOTE 5 below), TACAN, NDB, compass locator, DME fix; or a named fix
defined by a VOR radial, TACAN course, NDB bearing, or compass locator bearing intersecting a VOR or localizer course.​

2.​
Navigate to or from a VOR, TACAN, NDB, or compass locator.​

3.​
Hold over a VOR, TACAN, NDB, compass locator, or DME fix.​

4.​
Fly an arc based upon DME.​

NOTE​
−​

1.​
The allowances described in this section apply even when a facility is identified as required on a procedure (for example, “Note ADF required”).​

2.​
These operations do not include lateral navigation on localizer−based courses (including localizer back−course guidance) without reference to raw localizer data.​

3.​
Unless otherwise specified, a suitable RNAV system cannot be used for navigation on procedures that are identified as not authorized (“NA”) without exception by a NOTAM. For example, an operator may not use a RNAV system to navigate on a procedure affected by an expired or
unsatisfactory flight inspection, or a procedure that is based upon a recently decommissioned NAVAID. ​

4.​
Pilots may not substitute for the NAVAID (for example, a VOR or NDB) providing lateral guidance for the final approach segment. This restriction does not refer to instrument approach procedures with “or GPS” in the title when using GPS or WAAS. These allowances do not apply to procedures that are identified as not authorized (NA) without exception by a NOTAM, as other conditions may still exist and result in a procedure not being available. For example, these allowances do not apply to a procedure associated with an expired or unsatisfactory flight inspection, or is based upon a recently decommissioned NAVAID.​

5.​
For the purpose of paragraph c, “VOR” includes VOR, VOR/DME, and VORTAC facilities and “compass locator” includes locator outer marker and locator middle marker.​
Click to expand...

Hmm. Nor, I assume, would it preclude you from loading the localizer in nav2 and monitoring it while using the GPS on the primary CDI.
 
I just dug up a copy of an ops manual for a 121 carrier, and they fly localizers and BCs using LNAV derived from GPS/INS but the pilot must display the raw data on the PFD. So that's consistent.
 
I wish they'd quit messing with the rules...
 
John Collins said:
I maintain a current database in my aircraft, but there are still times when I may have a down level database (usually one month) in my aircraft and from time to time when flying someone else's airplane, I encounter an expired database.

That said, if one if flying an approach that requires a substitution of the DME, the only thing that needs to be verified is the particular DME lat-long location, which is included on the enroute charts for VORTAC and VOR-DME. Total time to check, about 20 seconds.

If the approach is in the database, then the only thing that needs to be confirmed is that the date on the current chart is the same as or before the database effective date. Approach Charts newer than Oct 2009 have incorporated a procedure amendment date that only changes when the change affects the procedure in the database. This allows older databases to be used when changes that don't affect the database require the chart to be updated. Many instrument pilots are not aware of the new format and what its significance is.
Click to expand...

This isn't directed at you John, but your post hit a nerve that has been irritating me lately - I'm a member of a rather large flying club with some overall well maintained planes. However, one problem we have is that alot of the owners advertise (and price accordingly) their aircraft as having IFR GPS. Problem is that many don't bother to regulary update the things. Kind of problematic for a renter to show up and find that the database is a year old. If an out of town owner can arrange for routine maintence, oil changes, aircraft washing....etc, why the hell can't they update the bloody GPS?
 
Fearless Tower said:
This isn't directed at you John, but your post hit a nerve that has been irritating me lately - I'm a member of a rather large flying club with some overall well maintained planes. However, one problem we have is that alot of the owners advertise (and price accordingly) their aircraft as having IFR GPS. Problem is that many don't bother to regulary update the things. Kind of problematic for a renter to show up and find that the database is a year old. If an out of town owner can arrange for routine maintence, oil changes, aircraft washing....etc, why the hell can't they update the bloody GPS?
Click to expand...

That's a good point. Most of the fleets around here require DB subscriptions for IFR airplanes as a condition of the plane being put on the rental line.
 
Fearless Tower said:
This isn't directed at you John, but your post hit a nerve that has been irritating me lately - I'm a member of a rather large flying club with some overall well maintained planes. However, one problem we have is that alot of the owners advertise (and price accordingly) their aircraft as having IFR GPS. Problem is that many don't bother to regulary update the things. Kind of problematic for a renter to show up and find that the database is a year old. If an out of town owner can arrange for routine maintence, oil changes, aircraft washing....etc, why the hell can't they update the bloody GPS?
Click to expand...

It would irritate me as well. It sounds like your flying club needs to make a policy decision to require the leasebacks to update the databases.

If I had my druthers, I would like to be able to purchase a database update subscription for my GNS530W on a 56 day update basis that coincided with the AeroNav TPP cycle. I wish that Garmin would have the same database policy that HBK has, where you have more choices and an extended time to use the updates that you have purchased.
 
FlyNE said:
That was my understanding as well, but the letter that Clay posted differs from that.

Clay, is that letter from your ops department?
Click to expand...

Its is right out of the latest revision of the ops manual 5/2011, that being said I understand it as current even with the 2009 date. It was given by our POI, thats as far as I can take that here.

If there is a segment of the approach that requires tracking of the localizer ,then we have to be tracking a localizer. All that really means is that we have raw data displayed on the primary HSI and use the GPS screen for overall sit. awareness or for whatever we want...

I believe to use the GPS during the procedure turn portion of a loc appch you would need to overide the VLOC/GPS selection initiated by the unit of VLOC so that offers a good hint right there.
 
Last edited:
taters said:
Its is right out of the latest revision of the ops manual 5/2011, that being said I understand it as current even with the 2009 date. It was given by our POI, thats as far as I can take that here.

If there is a segment of the approach that requires tracking of the localizer ,then we have to be tracking a localizer. All that really means is that we have raw data displayed on the primary HSI and use the GPS screen for overall sit. awareness or for whatever we want...

I believe to use the GPS during the procedure turn portion of a loc appch you would need to overide the VLOC/GPS selection initiated by the unit of VLOC so that offers a good hint right there.
Click to expand...

Couldn't you output the raw data to a second CDI and use the GPS to drive your HSI? As long as you didn't need the second nav to identify a fix...which you shouldn't if you're using the GPS to identify them. It would meet the letter of the law.
 
FlyNE said:
Couldn't you output the raw data to a second CDI and use the GPS to drive your HSI? As long as you didn't need the second nav to identify a fix...which you shouldn't if you're using the GPS to identify them. It would meet the letter of the law.
Click to expand...
You can set a 430 to vloc and drive the airplane CDI, but still use the NAV page CDI.

Or drive the second CDI from the second nav radio with the localizer, and couple the autopilot to the GPS on CDI #1.

As long as you've got a second nav radio and CDI you can monitor with that and be legal.
 
I'm not sure how relevant this is to this discussion since it is from our avionics manual (Honeywell Primus Epic), not a 430W but...

5. When using FMS guidance for conducting instrument approach procedures other than RNAV (GPS) or RNAV (RNP) that do not include “or GPS” in the title of the published approach procedure, the flight crew must verify that the procedure specified navigation facility and associated avionics are operational. Navigation information from the specified navigation facility must be displayed to the flight crew during the approach.
Click to expand...
So we can fly the approach with the FMS but the other type of navigation must be displayed somewhere.

10. The flight crew must verify the active navigation source is LOC or BC (green needles) prior to crossing the final approach fix for ILS, LOC, LOC-BC, LDA, and SDF approach procedures.
Click to expand...
This would mean we could do the PT on the FMS but would need to switch to the primary source before the FAF for these types of approaches.
 
FlyNE said:
Couldn't you output the raw data to a second CDI and use the GPS to drive your HSI? As long as you didn't need the second nav to identify a fix...which you shouldn't if you're using the GPS to identify them. It would meet the letter of the law.
Click to expand...

flying in my own plane that would be fine..in fact at my last job I did it all the time in the Bonanzas

where I work no... the SOP is #1 nav on the HSI is the bonafide Primary nav source for the appch.
 
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