[問題] 專有名詞請教

[josephairs (weiserhorner)]

以下文章出自

https://goo.gl/MvsFkY

為了方便看上下文先貼前幾段

WASHINGTON—The governments of Australia, China and Malaysia have long said
that the underwater search for Malaysia Airlines Flight MH370 will end when a
120,000 km2region along the so-called Seventh Arc in the southern Indian
Ocean has been combed for the wreckage—work that is expected to be complete
in January.

Despite the massive underwater search zone, the only traces of the aircraft
found to date have been recovered pieces from islands in the western Indian
Ocean and Africa.

However, a new analysis by the Australian government-funded Commonwealth
Scientific and Industrial Research Organization (CSIRO) could provide the
impetus to continue somewhat longer. This particular study was paid for the
Australian Air Transport Safety Bureau, the agency overseeing the MH370
search.

The agency’s Oceans and Atmospheres business unit analyzed the likely drift
paths of various pieces of recovered debris from the Boeing 777-200ER, and
determined that certain portions of the Seventh Arc search area that were not
included in the underwater search may hold the key to finding the aircraft.
Of particular interest, according to the CSIRO, is the area near the
intersection of the Seventh Arc and 35 deg. south latitude (see map).

While the underwater search along the Seventh Arc covered a rectangular area
of 40 nm between 36-39.3 deg. south latitude, the search was limited to a
10-21 nm cross-track between 32.8-36 deg. south latitude. The smaller width
near 35 deg. could be critical, as the ATSB estimated that the 777 could have
flown as far as 25 nm away from the center of the arc after running out of
fuel, based on its final satellite contact.
水下搜尋沿著第七弧南緯36~39.3度之間，一個40海浬長的長方形，南緯32.8~36度的交
錯航跡搜索寬度限縮在10~21海浬，在南緯35度寬度更小可能是關鍵，ATSB估計根據衛星
訊號顯示，這架777在燃油耗盡之後最遠可能飛離海灣中心25海浬。

上面這段看不大懂

請問以下幾點

1. seventh arc中文怎麼翻?
2. cross-track 交錯航跡 是指像空拍機飛的來回路徑嗎?
3. 上面這樣翻譯有沒有誤會的地方? 為什麼搜尋寬度(還是長度)會縮小?

先感謝專業的大大們回答了



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※ 文章網址: https://www.ptt.cc/bbs/Aviation/M.1483622987.A.2F0.html
→ prussian: the seventh arc 是指衛星為圓心，該機第七次通訊時的距
→ prussian: 離為半徑的球體，和地球相交的圓，去除掉條件不可能的部
→ prussian: 份之後，剩下是飛機可能地點的圓弧
→ prussian: 要怎麼翻要看上下文先前怎麼描述，這不是常用的專有名詞
→ josephairs: 謝謝您
推 kugh2005: 有看有推
推 Chiardy: 長知識
推 xylophone135: 專業推
→ prussian: cross-track 應該是指沿著圓弧去cross可能的航跡來搜索
→ prussian: 因為mh370 最後一次在雷達上出現是在北半球，7th arc 卻
→ prussian: 在南半球(arc 另一部份當初畫到阿富汗的那段被排除了
→ prussian: 從最後已知點到 7th arc, 模擬出來的多條autopilot航跡
→ prussian: 在 arc 和這些航跡交會的地方搜索
→ josephairs: 太專業了。再次感謝
推 lidocaine: