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#21
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GPS Question
Um, OK, I'm thick. I don't get what substitution rule I'm still
missing? With either approach you're using the VOR head for lateral guidance and reading the distance from some fix in the GPS database from the GPS head. Even the example approach used for how to do a DME ARC in the KLN 94 GPS manual is an VOR/DME approach using an arc. I guess the idea is that your position "on track" and "along track" need differing amounts of, for lack of a better word, attention. You are pointed along track and will cover all the along-track positions. You want to remain on track, and not left or right of track. For a regular VOR approach, it is the VOR that keeps you on track. DME just reports your "along track" progress. For a DME arc it's the reverse. You stay "on track" referring to the DME, and the VOR just reports your "along track" progress. Jose -- Money: what you need when you run out of brains. for Email, make the obvious change in the address. |
#22
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GPS Question
This article refers to the LDA/DME RWY 23 approach at EKO in Figure B.
I tried "flying" that approach on the Garmin 430 simulator and blew it the first time because I was watching the distance readout on the Garmin primary nav page (1st Nav page). I forgot that the unit indicates distance to the next waypoint. After crossing the FAF, the distance field on the nav page indicates the GPS distance to the next waypoint (missed approach point here) rather than distance from the FAF or the DME reference point. What probably threw me off was that the AOPA article cautions readers that while DME units will count DOWN to the missed approach point (because the path is towards the DME reference point), GPS units will count UP from the FAF. In contrast, the 430 counts DOWN to the next waypoint (the missed approach point here). To count up from the FAF, I'd probably have to hit OBS when approaching the FAF (though didn't try it). What procedure would other users of Garmin 430/530 units use with this approach? Ideally, I'd want to see either the primary nav page or the map page with distance shown from the DME reference point (so that I don't have to do math in my head during the approach to calculate distance from the FAF). |
#23
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GPS Question
On Fri, 10 Mar 2006 17:03:16 GMT, "Steven P. McNicoll"
wrote: "Peter Clark" wrote in message .. . Um, OK, I'm thick. I don't get what substitution rule I'm still missing? With either approach you're using the VOR head for lateral guidance and reading the distance from some fix in the GPS database from the GPS head. Even the example approach used for how to do a DME ARC in the KLN 94 GPS manual is an VOR/DME approach using an arc. But you're not using the VOR head for lateral guidance and reading the distance from some fix in the GPS database from the GPS head with either approach. The VOR/DME or TACAN Z RWY 15 at MTN would have you using DME for lateral guidance and determining your position on the final approach course from crossing VOR radials. If you substituted GPS for DME on that approach you'd be substituting for DME where it was the principal instrument approach navigation source. OK, I'm not trying to be obtuse here, I'd really like to understand what I'm doing wrong. I'm flying along using the GPS head to tell me I'm on an arc (X) miles from (Y) transmitter, twisting the VOR head every 10deg or so until I hit the leadin radial and then turn inbound (or in the case of the DC approach see the runway or go missed). The manual documents this scenario. The AOPA article seems to document the same usage. Yet it's not allowed by the substitution rules? |
#24
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GPS Question
"Peter Clark" wrote in message ... OK, I'm not trying to be obtuse here, I'd really like to understand what I'm doing wrong. I'm flying along using the GPS head to tell me I'm on an arc (X) miles from (Y) transmitter, twisting the VOR head every 10deg or so until I hit the leadin radial and then turn inbound (or in the case of the DC approach see the runway or go missed). The manual documents this scenario. The AOPA article seems to document the same usage. Yet it's not allowed by the substitution rules? AIM para 1-1-19.f.1.(b)(6): "Charted requirements for ADF and/or DME can be met using the GPS system, except for use as the principal instrument approach navigation source. What serves as the principal instrument approach navigation source for the ILS/DME RWY 2 at DRO? What serves as the principal instrument approach navigation source for the VOR/DME RWY 15 at MTN? |
#25
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GPS Question
Yes, because the DME is the "principal instrument approach
navigation source" - that approach is a DME arc to the runway. Sounds like pure speculation to me. Can you support with any FAA material? |
#26
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GPS Question
On Sat, 11 Mar 2006 04:12:16 GMT, "Steven P. McNicoll"
wrote: "Peter Clark" wrote in message .. . OK, I'm not trying to be obtuse here, I'd really like to understand what I'm doing wrong. I'm flying along using the GPS head to tell me I'm on an arc (X) miles from (Y) transmitter, twisting the VOR head every 10deg or so until I hit the leadin radial and then turn inbound (or in the case of the DC approach see the runway or go missed). The manual documents this scenario. The AOPA article seems to document the same usage. Yet it's not allowed by the substitution rules? AIM para 1-1-19.f.1.(b)(6): "Charted requirements for ADF and/or DME can be met using the GPS system, except for use as the principal instrument approach navigation source. What serves as the principal instrument approach navigation source for the ILS/DME RWY 2 at DRO? What serves as the principal instrument approach navigation source for the VOR/DME RWY 15 at MTN? OK, using that as a baseline then GPS wouldn't be a permissible substitute for DME in any approach using a DME arc, so why would it be documented in the manuals if it's not permissible? |
#27
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GPS Question
"Peter Clark" wrote in message ... AIM para 1-1-19.f.1.(b)(6): "Charted requirements for ADF and/or DME can be met using the GPS system, except for use as the principal instrument approach navigation source. What serves as the principal instrument approach navigation source for the ILS/DME RWY 2 at DRO? What serves as the principal instrument approach navigation source for the VOR/DME RWY 15 at MTN? OK, using that as a baseline then GPS wouldn't be a permissible substitute for DME in any approach using a DME arc, so why would it be documented in the manuals if it's not permissible? You didn't answer the questions. We can proceed only after you answer the questions. |
#28
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GPS Question
Greg Esres wrote:
Sounds like pure speculation to me. Can you support with any FAA material? Doesn't seem speculative to me. The FAA material is the fact that the final approach couse is a DME ARC printed on the approach chart in bold type. A good understanding of approach chart symbology would make that apparent. Also, there are the TERPS: 523. FINAL APPROACH SEGMENT. TACAN and VOR/DME final approaches may be based either on arcs or radials. The final approach begins at a FAF and ends at the MAP. The MAP is always marked with a fix. a. Radial Final Approach. Criteria for the radial final approach are specified in paragraph 513. b. Arc Final Approach. The final approach arc shall be a continuation of the intermediate arc. It shall be specified in NM and tenths thereof. Arcs closer than 7 miles (15 miles for high altitude procedures) and farther than 30 miles from the facility shall NOT be used for final approach. No turns are permitted over the FAF. (1) Alignment. For straight-in approaches, the final approach arc shall pass through the runway threshold when the angle of convergence of the runway centerline and the tangent of the arc does not exceed 15 degrees. When the angle exceeds 15 degrees the final approach arc shall be aligned to pass through the center of the airport and only circling minimums shall be authorized. See Figure |
#29
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GPS Question
On Sat, 11 Mar 2006 20:17:46 GMT, "Steven P. McNicoll"
wrote: "Peter Clark" wrote in message .. . AIM para 1-1-19.f.1.(b)(6): "Charted requirements for ADF and/or DME can be met using the GPS system, except for use as the principal instrument approach navigation source. What serves as the principal instrument approach navigation source for the ILS/DME RWY 2 at DRO? What serves as the principal instrument approach navigation source for the VOR/DME RWY 15 at MTN? OK, using that as a baseline then GPS wouldn't be a permissible substitute for DME in any approach using a DME arc, so why would it be documented in the manuals if it's not permissible? You didn't answer the questions. We can proceed only after you answer the questions. OK. I believe the answer is the GS/localizer and VOR respectively. |
#30
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GPS Question
"Peter Clark" wrote in message ... OK. I believe the answer is the GS/localizer and VOR respectively. Why did you choose VOR for the VOR/DME RWY 15 at MTN? Do you see VOR serving the same role there as the localizer does for the ILS/DME RWY 2 at DRO? |
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