Prior to takeoff, we'll need all baggage to be stowed properly.

在起飛前我們需要將行李妥善放置好。

Your seats move to the upright position and your seat belts securely fastened.

你的椅背需要豎直並繫好安全帶。

Thank you.

謝謝。

Once everyone's set, the plane lurches away from the terminal and the lights inside the cabin go out.

當大家都準備，飛機從機場跑道起飛，然後機艙內的燈熄滅。

It happens without mention.

這一切都顯得理所當然。

You may not have even fully noticed that it does happen.

你可能甚至沒有完全注意到這一切。

One reason has to do with what's called "the 90-second rule."

這一切與一個稱為「90 秒原則」有關。

It's a guideline that dictates many of the mundane, but absolutely crucial in-flight procedures.

這是一個主導很多常見，但絕對重要的飛行間程序的規則。

In the 1920's, the preflight routines we now know by heart were nonexistent.

在 1920 年代，飛行前例行檢查就我們內心所知是不存在的。

Basically, pilots would tell passengers to put on a parachute and briefly show them how to use it.

基本上，飛行員會告知乘客穿上降落傘，並簡略地告訴他們該怎麼使用。

During that time, commercial air traffic saw a death for every 13,500 miles flown.

在那段期間內，商業飛行事故而言，平均每飛行 13500 英里 (約 21726 公里) 會有一人死亡。

It's not good.

這不是件好事。

But there was one airline that performed much better than the industry median.

但有一家航空公司在這方面表現得明顯比整體產業均值好。

That was the government-owned air-mail system and it was run with an eye on safety.

是政府營運的航空郵件系統，而這間公司非常重視安全問題。

Pilots were selected after careful medical examinations, engines were checked once every 100 hours of flight time, and after every single flight, there was a 180-point inspection checklist.

飛行員須接受仔細的醫療檢驗才能任職，引擎在每飛行 100 小時就需檢查一次，且每飛行一次會有一個「180 分檢測表」來進行檢測。

Because of that thoroughness, the air mail system saw a fatality for every 789,000 miles flown.

因為這樣全面的防護，這間航空郵件系統在每飛行 789,000 英里才會有一個死亡案例。

The industry took notice and things started to change.

業界發現了這件事情而情況就開始改變。

By 1935, the Aeronautics Branch, now called the Bureau of Air Commerce had a list of new safety regulations.

在 1935 年時，航空分會，現稱「航空商務局」有了新的安全規範。

Some of those new rules for planes were the requirement of co-pilots, two way radios, limits on the hours pilots can be in the air, and that planes needed to have multiple engines, get the ability to fly on one engine in the case of an emergency.

有些關於飛機方面的新規範包括要有一位副駕駛員、雙向無線電、限制飛行員的飛行時數與飛機需有多個引擎，有能力在碰到緊急事故時依靠單顆引擎飛行。

By 1937, the number of pilots increased from 1927 by 700 times.

1937 年時，飛行員的數量比 1927 年多了 700 倍。

Meanwhile, deaths went down 10 times over that same time period.

死亡率在同時間下降了 10 倍。

In 1967, the Bureau of Air Commerce became the Federal Aviation Administration.

在 1967 年，航空商務局變成美國聯邦航空管理局。

Soon after, they required all airlines to include oxygen masks, flotation devices, and emergency exit markings making it clear to passengers where the closest exits are.

不久之後，美國聯邦航空管理局要求所有航空公司在飛機上備齊氧氣罩、漂浮設備還有設置緊急出口標誌，讓乘客知道最近的出口在哪裡。

All part of what's called the 90-second rule.

而現在來介紹「90 秒原則」。

The 90-second rule requires airlines using planes with a capacity of 44 people or more to be able to demonstrate the ability to conduct an emergency evacuation in 90 seconds or less.

90 秒原則要求所有航空公司至少需要有 44 人有能力可以在遇到緊急狀態時，在 90 秒內疏散乘客。

Even if half the exits are blocked.

就算是一半的出口被堵住了也一樣。

Even today airlines have to run tests to prove to the FAA that they comply.

就算到了現在，所有航空公司還是要通過測驗向美國聯邦航空管理局證明機組人員有這樣的能力。

The Discovery Channel filmed a 90-second test for an Airbus A380.

Discovery 頻道紀錄下了一段空中巴士 A380 在進行 90 秒原則考核時的影像。

It's dramatic stuff.

非常戲劇化。

Believe it or not, one of the major hurdles to being successful in the 90-second rule is people trying to grab their belongings to take with them.

信不信由你，但通過 90 秒原則考核最主要的阻礙是乘客想要在逃生時將他們的行李帶在身上。

Leave your stuff.

就別管行李了吧！

So, that leads to our initial question, why do planes turn off their lights within the cabin at takeoff and landing?

所以，這也回到了我們最初的問題，為什麼在起降時要將機艙內的燈關掉呢？

The lights inside the cabin are turned off because of the time it takes for eyes to adjust to the dark.

關燈的原因是在於要讓眼睛有適應黑暗的時間。

If an emergency during takeoff or landing caused the lights to suddenly go out, no one's eyes would be adjusted making it harder to evacuate, especially in 90 seconds.

如果在起降時發生緊急事故讓燈突然熄滅，沒有人的眼睛可以適應光線的變化，這樣會使疏散作業更加困難，更何況要在 90 秒內完成。

The retina at the back of the eye has two kinds of cells, rods and cones, which take light in turning them into neural signals.

眼睛的視網膜上有兩種不同細胞，視桿與視錐細胞，它們能將光線轉會成神經信號。

The cones help when it's light out and rods handle seeing at night.

視錐細胞負責有光時的視覺而視桿負責夜視能力。

When the lights go out, the cones adjust faster—within nine to 10 minutes.

當沒有光線時，視錐細胞可以在九到十分鐘內調整完畢。

While the rods whose job it is to handle low light can take as long as 30 minutes to see as well as they'll be able to.

相較之下視桿細胞的工作是處理較低亮度的狀況，而且需要花 30 分鐘來調整到可以讓我們恢復視覺。

There's a good reason why the lights are turned off specifically at takeoff and landing.

所以這是關燈是很好的原因，尤其是在飛機起降時。

That's when most plane accidents occur.

因為在起降時是事故率最高的時候。

Boeing looked into accidents that led to fatalities from 2006 to 2017.

波音公司查看了自 2006 至 2017 年導致死亡的意外事件。

They found that 13 percent happened within the first three minutes of the flight, which is takeoff in the initial climb, while 48 percent of accidents that caused fatalities happened during the final descent and landing, which are the last eight minutes of the flight.

他們發現這些意外有 13% 是發生飛行的前 3 分鐘內，即起飛爬升的階段，還有 48% 是發生在下降與降落的階段，這一般是在飛行最後 8 分鐘。

Along with the lights being dimmed, the whole pre-flight routine is providing passengers with the directions to get to safety as fast as possible.

與關燈相同，整個飛行前檢查例行作業是提供乘客盡快達到安全狀態的方式。

The only thing that the 90-second rule can't plan and test for is that during an emergency, people are going to panic.

唯一一件 90 秒原則無法預估與檢測的事為當乘客遇到緊急事件時，他們會相當恐慌。

Hey, everyone. Thank you so much for watching.

大家好，謝謝你們收看這支影片。

If you like what you saw please like, comment, subscribe, and make sure you hit that little bell so that you get notifications for when Cheddar posts its new content.

如果你喜歡這支影片，請按喜歡，留言並訂閱，並按下小鈴鐺就可以收到 Cheddar 新內容的通知！

We have so much fun stuff coming, please keep watching.

我們還有很多有趣的東西即將發行，所以要來看喔！