{"id":5022,"date":"2025-02-01T18:19:53","date_gmt":"2025-02-01T10:19:53","guid":{"rendered":"https:\/\/caucanimax.com\/blog\/?p=5022"},"modified":"2025-02-01T18:19:54","modified_gmt":"2025-02-01T10:19:54","slug":"question-about-35m-difference-between-the-lda-on-nd-and-published-in-airport-data","status":"publish","type":"post","link":"https:\/\/caucanimax.com\/blog\/question-about-35m-difference-between-the-lda-on-nd-and-published-in-airport-data\/","title":{"rendered":"\u5173\u4e8eANF \u6570\u636e\u5e93\u4e2dLDA\u8d85\u8fc7\u822a\u56fe35\u7c73\u7684\u7591\u95ee"},"content":{"rendered":"

\u5728\u4e0b\u964d\u51c6\u5907\u4e2d\uff0c\u8bbe\u7f6e\u8981\u68c0\u67e5 ND \u4e0a\u7684\u53ef\u7528\u7740\u9646\u8ddd\u79bb\u4e0d\u80fd\u8d85\u8fc7\u822a\u56fe\u4e0a 35m\uff1a<\/p>\n

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

\u4ec0\u4e48\u60c5\u51b5\u4e0b\uff0cANF \u6570\u636e\u5e93\u4e2d\u7684 LDA \u4f1a\u548c\u822a\u56fe\u4e0a\u7684\u4e0d\u4e00\u81f4\u5462\uff1f\u5982\u679c\u662f\u8dd1\u9053\u7f29\u51cf\u5bfc\u81f4\u7684\uff0c\u4e3a\u4ec0\u4e48\u4e0d\u80fd\u76f4\u63a5\u53bb\u4fee\u6539 ANF \u6570\u636e\u5e93\u4e2d\u7684 RWY SHIFT\uff1f\u8fd9\u4e2a 35m \u7684\u6570\u503c\u53c8\u662f\u4e00\u53e5\u4ec0\u4e48\u6765\u5b9a\u7684\u5462\uff1f<\/p>\n

<\/p>\n

\u7a7a\u5ba2\u89e3\u91ca\u4e24\u4e2a\u6570\u636e\u5e93\u8ddd\u79bb\u7684\u504f\u5dee\u53ef\u80fd\u662f\u7531\u4e8e ANF \u6570\u636e\u5e93 LDA \u6570\u636e\u7f16\u7801\u9519\u8bef\/\u8fc7\u671f\uff0c\u6216\u8005\u662f\u4e34\u65f6\u8dd1\u9053\u5167\u79fb\u9020\u6210\u7684\u3002\u7f16\u7801\u9519\u8bef\u4f1a\u5f71\u54cd BTV \u4f7f\u7528\u3002<\/p>\n

\u800c\u5982\u679c\u8dd1\u9053\u6709\u4e34\u65f6\u5167\u79fb\uff0c\u5e94\u8be5\u5148\u5728 ANF \u6570\u636e\u5e93\u4e2d\u505a\u76f8\u5e94\u7684\u4fee\u6539\uff0c\u518d\u5bf9\u6bd4\u4fee\u6539\u540e\u7684 LDA \u4e0e\u822a\u56fe\u4e0a\u7684 LDA\uff0c\u800c\u4e0d\u662f\u76f4\u63a5\u5bf9\u6bd4\u3002\u5982\u679c ANF \u6570\u636e\u5e93\u4e2d\u4fee\u6539\u4e86shift\u7684 LDA \u6bd4\u822a\u56fe\u51cf\u53bb\u4e34\u65f6\u5167\u79fb\u540e\u7684 LDA \u8fd8\u591a 35m \u4ee5\u4e0a\uff0c\u5219\u4e0d\u80fd\u4f7f\u7528 BTV\u3002<\/p>\n

\u81f3\u4e8e 35m \u7684\u6765\u6e90\uff0c\u7a7a\u5ba2\u6ca1\u6709\u5177\u4f53\u89e3\u91ca\uff0c\u53ea\u662f\u8bf4\u8fd9\u662f\u4e00\u4e2a\u4e3a\u4e86\u9632\u6b62\u51b2\u51fa\u8dd1\u9053\u7684\u5b89\u5168\u88d5\u5ea6\u3002\u5982\u679c\u8bef\u5dee\u8d85\u8fc7 35m\uff0c\u5219\u8bf4\u660e ANF \u6570\u636e\u5e93\u6574\u4f53\u4e0a\u5b58\u5728\u4e0d\u51c6\u786e\u6027\uff0c\u6b64\u65f6\u4e0d\u5e94\u4f7f\u7528 BTV\u3002<\/p>\n

\n

\u539f\u6587\uff1a<\/strong><\/p>\n

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

As FCOM PRO-NOR-SOP-160 A DESCENT PREPARATION – AUTOBRAKE:<\/p>\n

“The LDA displayed on the ND (left upper corner) must not exceed the LDA published in airport data by more than 35 m (115 ft).”<\/p>\n

Under what circumstances would there be a difference between the LDA on ND and published in airport data? Is it due to an inconsistent database cycle, or a temporary runway shift?<\/p>\n

Where does the figure of 35 meters come from?<\/p>\n

If it is because of a temporary runway shift, and even if it exceeds 35 meters, couldn’t it be just modified in ANF database by crew? Why is a limit value of 35 meters set?<\/p>\n

A1<\/strong><\/p>\n

Please be informed that the difference between the LDA displayed on the ND versus airport chart can be due to a wrong\/outdated coding of the LDA in the ANF database or temporary runway shift<\/span>. Therefore, the SOP asks the flight crew to check that the runway length coded in the ANF database and the data from the chart are consistent.<\/p>\n

On the A350, a wrong coding of the LDA in the ANF database will affect the BTV function only<\/span> (and not BRK MED or manual braking). Even though ROW\/ROP remains available in these conditions (and will trigger the appropriate alerts if necessary), BTV should not be used if the ANF LDA exceeds the published LDA by more than 35 m (115 ft). The 35 m value is the margin to prevent a runway excursion.<\/span><\/p>\n

We would like to inform CSC that a discrepancy of more than 35 m indicates a global inaccuracy<\/span>\u00a0of the ANF data for this runway, and that in this case BTV should not be used. In the case when a shortening is entered (in fact the runway length reduction is applied from either from the runway threshold or runway end) then the reference data should be correct.<\/p>\n

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

Does this mean, if there is a temporary runway shift, it would be more appropriate to first make the corresponding modifications to the temporary shift in the ANF database, and then compare the modified ANF LDA with the LDA from the charts after subtracting the temporary shift.<\/span><\/p>\n

If, after the modification, the LDA in the ANF database still exceeds the chart’s LDA (after subtracting the temporary shift) by more than 35 meters, then the BTV function should not be used. This is because such a discrepancy indicates a potential global inaccuracy in the database, compromising the reliability of BTV operations and safety.<\/p>\n

A2<\/strong><\/p>\n

Your understanding is correct.<\/span><\/p>\n

In case of known<\/span>\u00a0runway length reduction not correctly coded in the ADB, the flight crew should use the \u201cMODIFY RUNWAY\u201d function of the ANF to manually enter the appropriate shift (either from runway threshold or runway end). This ensures a correct functioning of ROW\/ROP\/BTV.<\/p>\n

As per Airbus SOP,\u00a0BTV should not be used if the ANF LDA exceeds the published LDA by more than 35 m (115 ft).<\/p>\n","protected":false},"excerpt":{"rendered":"

\u5728\u4e0b\u964d\u51c6\u5907\u4e2d\uff0c\u8bbe\u7f6e\u8981\u68c0\u67e5 ND \u4e0a\u7684\u53ef\u7528\u7740\u9646\u8ddd\u79bb\u4e0d\u80fd\u8d85\u8fc7\u822a\u56fe\u4e0a 35m\uff1a \u4ec0\u4e48\u60c5\u51b5\u4e0b\uff0cANF \u6570\u636e\u5e93\u4e2d\u7684 LD … \u9605\u8bfb\u66f4\u591a<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[113],"tags":[],"ppma_author":[5],"class_list":["post-5022","post","type-post","status-publish","format-standard","hentry","category-fly"],"authors":[{"term_id":5,"user_id":2,"is_guest":0,"slug":"yaoguai","display_name":"\u5996\u602a","avatar_url":"https:\/\/secure.gravatar.com\/avatar\/dfe71d09a1a83f49a02a4400c69ef2c361c2d967eae2ffeeb6318b73a0da763f?s=96&r=g","0":null,"1":"","2":"","3":"","4":"","5":"","6":"","7":"","8":""}],"_links":{"self":[{"href":"https:\/\/caucanimax.com\/blog\/wp-json\/wp\/v2\/posts\/5022","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/caucanimax.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/caucanimax.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/caucanimax.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/caucanimax.com\/blog\/wp-json\/wp\/v2\/comments?post=5022"}],"version-history":[{"count":4,"href":"https:\/\/caucanimax.com\/blog\/wp-json\/wp\/v2\/posts\/5022\/revisions"}],"predecessor-version":[{"id":5029,"href":"https:\/\/caucanimax.com\/blog\/wp-json\/wp\/v2\/posts\/5022\/revisions\/5029"}],"wp:attachment":[{"href":"https:\/\/caucanimax.com\/blog\/wp-json\/wp\/v2\/media?parent=5022"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/caucanimax.com\/blog\/wp-json\/wp\/v2\/categories?post=5022"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/caucanimax.com\/blog\/wp-json\/wp\/v2\/tags?post=5022"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/caucanimax.com\/blog\/wp-json\/wp\/v2\/ppma_author?post=5022"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}