UP IN SMOKE九霄煙雲
PHIL HEARD finds how volcanic eruptions affect Cathay Pacific’s operations Phil Heard探討火山爆發對國泰航空的運作有何影響
VOLCANOES. THEY ARE something of a regular inconvenience for travellers around Asia, with the ‘ring of fire’ stretching up from the tropics above Australia, up the Asian coast past Japan and into the frozen Aleutian Islands and mainland Alaska.
Mostly these sleeping giants grumble quietly, not affecting people’s travel plans. But once in a while there is a big eruption, and those plans go up in smoke – or more accurately, a cloud of ash.
For Mark Hoey, Cathay Pacific’s general manager operations, volcanoes are a frequent consideration. ‘ The amount of seismic activity in the past 18 months has increased,’ he says. ‘ Volcanoes have affected our operations pretty much every day over the past year, Bali and Indonesia most recently.’
That has meant adding fuel for anything between an extra few minutes to an hour of flying, and rerouting flights around ash clouds on hundreds of flights over the past few years.
So what’s the issue? While most of the pyrotechnics, quakes and lava flows are ground based, it’s what gets thrown up into the air that causes a problem to aviation. Back in 1982 – and this story has a happy ending – BA9, a British Airways Boeing 747, unwittingly flew into a volcanic ash cloud near Indonesia at night and lost power in all four engines, which were eventually restarted for a safe landing after a white-knuckle glide and a sandblasting of the cockpit windows.
The lesson was evident: stay well clear of volcanoes and ash clouds. Fast forward to 2010, and the eruption of cut-and-paste favourite Eyjafjallajökull on Iceland saw millions of tonnes of ash pumped into the atmosphere and aviation grounded across most of Europe as the significant ash cloud drifted southeast across the Atlantic.
Hoey says: ‘ What BA9 taught us was that volcanic ash can make a real mess of jet engines. What we learned from detailed research and new technology after 2010 is that there are safe ways to operate perfectly well and that the exclusion zones do not have to be so big.’
Now using satellite imagery, infrared pictures, particle sensors, webcams and wind charts for all altitudes, each flight is assessed on a case-by- case basis to mitigate risk. ‘ When there’s an eruption, we need to know first what we’re looking at,’ says Hoey. ‘Is it ash, steam, or just normal cloud forming over the warmth of the eruption?’
In years gone by, flights would simply be cancelled. But the data available now
由於環太平洋火山帶由澳洲以北的熱帶地區，沿著洲亞 海岸一直延伸而上，橫跨日本，直抵冰封的阿留申群島和阿拉斯加本土，因此火山會不時為亞洲的旅客帶來不便。
這些火山大部分時間都有如沉睡的巨人平在 地打呼嚕，並不影響客旅 的旅遊計。劃 但火山偶爾會發生大型發爆 ，這時旅的客 行程瞬即化為輕；煙 或者說得準確一點，應該是化為灰燼。
對國於 泰航空的航務總經理Mark Hoey來說，火山是需要經常注意和考慮的因素。他指出：「過去18個月，地震活動愈趨頻繁。，每去年 公司 天的航務幾乎都受到火山影響，最近受影響的地區括峇里和印尼。」
過去數年，火山活動造成的影響，令數以百計的航班需要增加燃油用量，應以 付可能延長數分鐘甚至一小時的額外飛行時間便，以 繞道避開火山灰雲。
雖然大部分因火山爆發而產生的煙火、地震和熔岩流都是在地面出現，但是火山噴發至空中的物質卻對航空構成問題。1982年，航班編號BA9的英國航空波音747客機不慎於夜晚飛進印尼附近的火山灰雲，致導 四台引擎全部失去動力。驚客機險地滑翔了一段時間，駕駛艙窗的 戶亦鋪滿沙，塵幸而引擎於千鈞一髮之間重啟新動，客機最後安全陸著 ，為故事寫下圓滿的結局。
這個故事的教相訓 當明顯，就是要遠離火山和火山灰雲。來到2010年，冰島的埃亞菲亞德拉冰蓋火山爆發百，數 萬噸火山
enables airlines to refine their decision making. ‘ With the new radar imagery we plot a 96-kilometre separation from the volcano (half of what it was a few years ago),’ says Hoey. ‘ Then depending on wind direction and other information we mark up lines to create fly, no-fly or “accessible only in good visual conditions” zones. Pilots can enter this information into their navigation computers and we can update them en route, too.’
Planes also take extra fuel so they can land elsewhere if conditions change. ‘ That gives us more flexibility and it means even if plans change we have somewhere to land,’ says Hoey.
But if conditions are unsafe, the operation stops. ‘ We cancelled a lot of flights in Bali and Indonesia last year when Mount Agung was banging away, and that’s frustrating for people. We do our best to keep things running, but it’s safety first.
‘ We don’t ever make a decision on the basis of one piece of data, we use as many as we can to corroborate our plans and then we fly it – but only when we’re confident that everything’s right.’ 灰噴發至大氣層，大片火山灰雲橫渡大西洋往東南方向飄去，致導 歐洲大部分地區的航線被逼停飛，成為航空公司應付類似情況的最佳教材。
Hoey表示：「BA9客機的遭遇給我予們的教，訓是火山灰能令噴射引擎變得一團糟。2010年後，我們透過詳細研究和嶄新科，技 可以完全如常運作，而禁飛區的範圍亦毋須。太大 」
現在，航空公司透過覆蓋有所 海拔高度的人造衛星影像、紅外線圖像、粒子偵測器、網絡攝影機和風向圖，可以獨立評估每班航班的飛行路線，從而降風低 險。Hoey表示：「當火山爆發我時， 們首先要噴知道出來的物質是火山灰蒸、 氣，抑或只是因爆發產生的熱力而形成的普通雲層？」
以往遇上火山爆發，航班往往都會被逼取消。但現時航空公司可依靠數據作來更精準的決。策 Hoey指出：「我利們 用全新的雷達影像，擬定出遠離火山96公里的航線，與幾年前相，比 禁飛距離大減一半。接著，我們根據風向和其他資訊，劃分出飛行區、禁飛區和日只限於視野條良件 好時通過』的區域。機師可將這些資訊輸入至導航電腦中，而公司亦可於飛行途中為機師提供最新資訊。」
客機同時亦會攜帶額外燃油，以便能 夠於飛行條件有變，時 可以改道降落於其他方地 。Hoey表示：「此舉為我們來帶 更大彈性，因為即使劃計 有我變， 們的航班也有地方可降落。」
不過，如果各項條件有安欠 全，就會停止飛行。「當阿貢火山於去年底持續爆發時，我們取消了大量峇里和印尼的航班，令旅客大失預算。我們當然會盡力維持航班運作，但始終是安全至上。」
「我從們 來不會只憑單一數據作來 決定，而是盡可能利用最大量的數據來支持我們的計，劃 並按照計啟。劃 程 不過，我們只會在肯定一切皆妥當的情況下才起飛。」
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