{"id":5359,"date":"2026-02-22T16:25:28","date_gmt":"2026-02-22T08:25:28","guid":{"rendered":"https:\/\/caucanimax.com\/blog\/?p=5359"},"modified":"2026-02-22T16:46:42","modified_gmt":"2026-02-22T08:46:42","slug":"several-issues-concerning-navdids-used-for-position-computation-and-deselection","status":"publish","type":"post","link":"https:\/\/caucanimax.com\/blog\/several-issues-concerning-navdids-used-for-position-computation-and-deselection\/","title":{"rendered":"\u5bfc\u822a\u53f0\u7528\u4e8e\u4f4d\u7f6e\u8ba1\u7b97\u548c\u62d2\u9009\u7684\u51e0\u4e2a\u95ee\u9898"},"content":{"rendered":"

\u611f\u8c22\u6765\u81ea\u540c\u4e8b\u7684\u95ee\u9898\u3002<\/p>\n

\u95ee\u9898 1<\/strong><\/p>\n

\u5728 FCOM DSC-34-NAV-20-10-60 POSITION COMPUTATION \u4e2d\uff0c\u6211\u4eec\u53ef\u4ee5\u770b\u5230\u7528\u6765\u8ba1\u7b97\u98de\u673a\u4f4d\u7f6e\u7684\u65b9\u5f0f\u548c\u6570\u636e\u6e90\u3002\u5176\u4e2d radio navaids \u53ef\u4ee5\u7528\u6765\u8ba1\u7b97 IR\/radio position (computed by the FMS)\u3002\u5728\u624b\u518c\u8fd9\u90e8\u5206\u63d0\u5230\u7684\u5bfc\u822a\u53f0\u53ea\u6709 VOR, DME, LOC\u3002<\/p>\n

\u800c\u5728 FCOM DSC-22-FMS-20-20-20 AF\uff0c\u63d0\u5230\u53ef\u7528\u4e8e\u4f4d\u7f6e\u8ba1\u7b97\u7684\u5bfc\u822a\u53f0\u8fd8\u5305\u62ec\u4e86 TACAN \u548c VORTAC\uff1a<\/p>\n

\"\"<\/a><\/p>\n

\u90a3\u4e48\uff0cTACAN \u548c VORTAC \u5230\u5e95\u80fd\u80fd\u5426\u7528\u4e8e\u4f4d\u7f6e\u8ba1\u7b97\uff1f<\/p>\n

<\/p>\n

\u95ee\u9898 2<\/strong><\/p>\n

\u5982\u679c\u4e00\u4e2a DVOR \u6216\u8005 VORTAC \u7684 VOR \u90e8\u5206\u6216\u8005 DME\/TACAN \u90e8\u5206\u4e0d\u5de5\u4f5c\uff0c\u53e6\u4e00\u90e8\u5206\u5de5\u4f5c\uff0c\u662f\u5426\u9700\u8981\u62d2\u9009\u8be5\u5bfc\u822a\u53f0\uff1f<\/p>\n

\u6bd4\u5982\u6d1b\u6749\u77f6 LAX\uff1a<\/p>\n

\"\"<\/a><\/p>\n

\"\"<\/a><\/p>\n

 <\/p>\n

\u95ee\u9898 3<\/strong><\/p>\n

\u5173\u4e8e\u62d2\u9009\u5bfc\u822a\u53f0\uff0cA320 \u548c A350 \u7684\u63cf\u8ff0\u7a0d\u6709\u4e0d\u540c\u3002A320 \u63d0\u5230\u5728\u4e0d\u53ef\u9760\u548c\u4e0d\u5de5\u4f5c\u65f6\u90fd\u9700\u8981\u62d2\u9009\uff0c\u800c A350 \u53ea\u63d0\u5230\u5728\u4e0d\u53ef\u9760\u65f6\u9700\u8981\u62d2\u9009\uff0c\u90a3\u4e0d\u5de5\u4f5c\u65f6\u8be5\u5982\u4f55\u64cd\u4f5c\u5462\uff1f<\/p>\n

\"\"<\/a> \"\"<\/a><\/p>\n

\u6bd4\u5982\u83ab\u65af\u79d1 UUWW \u7684\u4e00\u4e2a DVOR\uff1a<\/p>\n

\"\"<\/a><\/p>\n

 <\/p>\n

\u7a7a\u5ba2\u56de\u590d<\/strong><\/p>\n

\u95ee\u9898 1:<\/p>\n

\u7a7a\u5ba2\u98de\u673a\u4e0d\u5177\u5907\u5b8c\u6574\u7684<\/span> TACAN \u548c\/\u6216 VORTAC \u529f\u80fd\uff0c\u56e0\u4e3a\u8fd9\u4e9b\u5c5e\u4e8e\u519b\u7528\u529f\u80fd<\/span>\u3002\u4e0d\u8fc7\uff0c\u5f53 TACAN \u53f0\u7ad9\u53ef\u7528\u65f6\uff0cFMS \u53ef\u4ee5\u4f7f\u7528\u8be5\u53f0\u7ad9\u7684 DME \u529f\u80fd<\/span>\u3002\u5728 VORTAC\uff08VOR \u4e0e TACAN \u5171\u5740\uff09\u7684\u60c5\u51b5\u4e0b\uff0cFMS \u53ef\u4ee5\u4f7f\u7528 VOR \u529f\u80fd\u83b7\u53d6\u65b9\u4f4d\u4fe1\u606f<\/span>\uff0c\u540c\u65f6\u4f7f\u7528 TACAN \u7684 DME \u529f\u80fd\u83b7\u53d6\u659c\u8ddd<\/span>\u3002<\/p>\n

\u95ee\u9898 2:<\/p>\n

\u8d77\u98de\u65f6\u8fdb\u884c\u5bfc\u822a\u53f0\u62d2\u9009\u662f\u4e3a\u4e86\u5728 GPS PRIMARY \u4e22\u5931\u65f6\u907f\u514d FMS \u65e0\u7ebf\u7535\u66f4\u65b0\u51fa\u73b0\u9519\u8bef\u3002<\/p>\n

\u5f53 FMS \u4ec5\u4f9d\u8d56\u5355\u4e00 VOR\/DME \u8fdb\u884c\u5bfc\u822a\u65f6\uff0c\u5176\u4f4d\u7f6e\u53ef\u80fd\u53d8\u5f97\u4e0d\u51c6\u786e\uff0c\u8fd9\u53d6\u51b3\u4e8e\u6240\u4f7f\u7528\u5730\u9762\u53f0\u7ad9\u7684\u8d28\u91cf\u3002\u56e0\u6b64\uff0c\u5728\u5171\u5740\u53f0\u7ad9<\/span>\uff08\u4f8b\u5982 VOR\/DME \u6216 VORTAC\uff09\u4e2d\uff0c\u5982\u679c\u4ec5 DME\uff08\u6216 VOR\uff09\u90e8\u5206\u4e0d\u53ef\u7528<\/span>\uff0c\u5219\u5e94\u6309\u7167 FCOM PRO-NOR-SOP-60 \u201cMFD FMS Preparation\u201d \u4e2d \u201cNAVAIDS\u201d \u7ae0\u8282\u7684\u8981\u6c42\uff0c\u5c06\u6574\u4e2a\u53f0\u7ad9\u62d2\u9009<\/span>\u3002<\/p>\n

\u6b64\u5916\uff0c\u53ea\u6709 VORTAC \u624d\u5305\u542b VOR \u90e8\u5206\uff0c\u800c TACAN \u672c\u8eab\u4e0d\u5305\u542b\u3002\u5728 LAX NOTAM A0395\/25 N \u7684\u60c5\u51b5\u4e0b\uff0c\u6839\u636e FAA \u7f51\u7ad9\u4fe1\u606f\uff0cLAX \u7684 113.6 MHz \u5b9e\u9645\u4e0a\u662f\u4e00\u4e2a VORTAC\u3002<\/p>\n

\u95ee\u9898 3:<\/p>\n

\u7a7a\u5ba2\u786e\u8ba4\uff0c\u5728\u4e0d\u53ef\u7528\u548c\u4e0d\u53ef\u9760\u4e24\u79cd\u60c5\u51b5\u4e0b\uff0c\u53d7\u5f71\u54cd\u7684\u5bfc\u822a\u53f0\u90fd\u5e94\u88ab\u62d2\u9009<\/span>\u3002\u67d0\u4e9b\u5bfc\u822a\u53f0\u53ef\u80fd\u5728 AIP \u4e2d\u88ab\u5ba3\u5e03\u4e3a\u4e0d\u53ef\u7528\uff0c\u4f46\u4ecd\u5b58\u5728\u53f0\u7ad9\u6240\u6709\u8005\u672a\u5c06\u5176\u5173\u95ed\u7684\u98ce\u9669<\/span>\u3002<\/p>\n

\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0cFMS \u4ecd\u4f1a\u63a5\u6536\u5230\u53d1\u5c04\u7684\u6570\u636e\u5e76\u57fa\u4e8e\u8fd9\u4e9b\u6570\u636e\u8fdb\u884c\u8ba1\u7b97\uff0c\u4f46\u8fd9\u4e9b\u6570\u636e\u5f88\u53ef\u80fd\u662f\u9519\u8bef\u7684\u3002\u56e0\u6b64\uff0c\u4e3a\u4e86\u907f\u514d\u4e0e\u4e0d\u53ef\u7528\u5bfc\u822a\u53f0\u4ecd\u53ef\u80fd\u53d1\u5c04\u6570\u636e\u76f8\u5173\u7684\u4efb\u4f55\u95ee\u9898\uff0c\u7a7a\u5ba2\u5efa\u8bae\u5c06\u5176\u62d2\u9009\u3002<\/span><\/p>\n

\n

\u539f\u6587<\/strong><\/p>\n

Q<\/strong><\/p>\n

Q1<\/strong><\/p>\n

Are TACAN and VORTAC used for position computation?<\/p>\n

In FCOM DSC-22-FMS-20-20-20 AF, it states that TACAN and VORTAC are included among the navigation aids that can be used for position computation.<\/p>\n

![[Questions about NAVAIDs and position computation_image_1.png|600]]<\/p>\n

However, in the entire subsection FCOM DSC-34-NAV-20-10-60 POSITION COMPUTATION, only DME is mentioned.<\/p>\n

Therefore, are TACAN and VORTAC used for position computation?<\/p>\n

Q2<\/strong><\/p>\n

If either the VOR part or the DME\/TACAN part of a DVOR or VORTAC is inoperative while the another part is operative, is it necessary to deselect the navaid?<\/p>\n

For example, Los Angeles (LAX):<\/p>\n

![[Questions about NAVAIDs and position computation_image_2.jpg|400]]<\/p>\n

![[Questions about NAVAIDs and position computation_image_3.jpg|300]]<\/p>\n

Q3<\/strong><\/p>\n

Regarding the deselection of navaids, the descriptions for the A320 and A350 differ slightly. Is deselection required for the A350 when a navaid is unserviceable other than unreliable?<\/p>\n

![[Questions about NAVAIDs and position computation_image_4.png|600]]<\/p>\n

![[Questions about NAVAIDs and position computation_image_5.png|600]]<\/p>\n

For example:<\/p>\n

![[Questions about NAVAIDs and position computation_image_6.jpg|400]]<\/p>\n

A<\/strong><\/p>\n

Answer 1:<\/p>\n

Airbus Aircraft do not have full<\/span> TACAN and\/or VORTAC capability, as they are military functions<\/span>.<\/p>\n

However, the FMS is able to use the DME function of the TACAN station<\/span> when available.<\/p>\n

In the case of a VORTAC (VOR and TACAN collocated), FMS may use the VOR function for azimuth and the DME function<\/span> of the TACAN for slant range<\/span>.<\/p>\n

Answer 2:<\/p>\n

First, Airbus would like to kindly inform CSC that the navaid deselection at departure is performed in order to avoid erroneous FMS radio updating if GPS PRIMARY is lost.<\/span><\/p>\n

When basing its navigation on a single VOR\/DME, the FMS position may become inaccurate, depending on the quality of the ground station being used. As such, in the case of only the DME (or VOR) being unserviceable<\/span> in a co-located station, such as VOR\/DME or VORTAC, the entire station should be deselected<\/span> as per FCOM PRO-NOR-SOP-60 \u201cMFD FMS Preparation\u201d, \u201cNAVAIDS\u201d chapter.<\/p>\n

In addition, only a VORTAC has a VOR part, while a TACAN has not. In the case of LAX NOTAM A0395\/25 N, according to the website of the FAA, LAX 113.6Mhz is, in fact, a VORTAC.<\/p>\n

Answer 3:<\/p>\n

Airbus confirms that in both<\/span> unserviceable and unreliable cases, the affected navaid should be deselected<\/span>.<\/p>\n

A navaid may be declared unserviceable in the AIP, but there is still a risk that it is not turned off by the owner<\/span>. In that case, the FMS will still receive emitted data and perform calculations based on these data which are, however, likely erroneous data.<\/span><\/p>\n

Therefore, to avoid any issues linked to an unserviceable navaid which may or may not still emit data, Airbus recommendation is to deselect it.<\/p>\n","protected":false},"excerpt":{"rendered":"

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