同时，现代飞机的空气循环系统配备HEPA过滤器，可去除99.97%的微小颗粒，确保机舱内空气纯净如手术室。这不仅关乎乘客的舒适度，更是飞行安全的体现。下次飞行时，不妨留意这些高空中的卫生奇迹吧！

Toilets in the sky

空中如厕的奥秘

Using water to flush airplane toilets is a no go because of aircraft weight restrictions. No biggie; instead, planes use air. The standard evac (evacuation) system uses differential air pressure to empty the bowl, in a design originally patented byJames Kemper In 1975.

飞机因重量限制，无法像地面那样使用水冲洗厕所。但这并不是难题，因为飞机采用的是气压差排污系统。这一巧妙设计最初由James Kemper于1975年申请专利。

Waste tanks – where everything that goes down the toilet ends up – are usually located at the back of the plane, and often at the front, too.

在飞机上，排污箱通常位于机身的后部，有时也位于前部。

When you press the flush button, a valve opens at the bottom of the toilet bowl, connecting it to a pipe below. That pipe – and the waste tank – are pressured, which means that opening the valve creates a vacuum that sucks out what’s in the bowl.

当乘客按下冲水按钮时，马桶底部的阀门便会开启，与下方的管道相连。由于管道和废水箱均处于受压状态，因此阀门的开启会产生真空效应，迅速将马桶内的污物吸走。

“It’s like your vacuum cleaner – it sucks,” says Nigel Jones, an aircraft engineering expert fromKingston University in London who also sits on the accreditation committee of the UK’s Royal Aeronautical Society.

英国皇家航空学会认证委员会成员、伦敦金斯顿大学的飞机工程专家Nigel Jones解释道：“这就像使用吸尘器一样，会产生强大的吸力。”

“As you press the button, it opens the valve – and as soon as the valve opens, the suction draws it all out. Then the valve closes.”

他进一步说明，当按钮被按下时，阀门打开，吸力随即将污物吸走，然后阀门关闭。

That vacuum effect is going on continuously while the plane is in the air, says Jones – we just don’t hear it until we open the valve and connect the toilet to the system. When the plane is on the ground, however, the differential pressure isn’t there – meaning that the toilet flush is operated by a pump, which creates a vacuum in the tank. As the plane climbs into the air, and the differential pressure in the tank builds, the vacuum naturally forms and the pump stops.

飞机在空中飞行时，这种真空效应持续存在，只是我们在冲厕前无法察觉。然而，当飞机降落在地面时，压差消失，此时马桶的冲水功能需依赖水泵来产生真空。但当飞机再次升空，水箱内的压差增大，真空自然形成，水泵便停止工作。

Toilet bowls are Teflon coated. “So nothing sticks, and it doesn’t need much at all – the differential pressure clears everything mighty quickly,” says Jones.

为保证马桶的清洁，其表面涂有特氟龙涂层。Nigel Jones表示：“这样设计能确保污物不会粘附，而且冲洗迅速有效。”

Airlines choose how many toilets they want in a plane, and where they want them. Jones says that there are minimum numbers per aircraft, depending on size, but airlines can go above those if they want.

航空公司可根据飞机大小和需求决定安装厕所的数量和位置。虽然每架飞机都有最低的厕所数量要求，但航空公司可以选择超过这个标准。

Of course, a tank that’s filled needs to be emptied – and this is where “honey wagons” come in. These are airport servicing vehicles which empty the tank and take the contents to be processed on airport grounds.

当然，满载的废水箱需要定期清空。这时，“粪车”便派上了用场。这些机场服务车辆负责将废水箱运至机场指定地点进行处理。

It’s a well honed process with 50 years of history – so does that mean things will stay the same forever? Jamco, a Japanese company which currently has a 50% share of the aircraft toilet market, has already pushed boundaries, building onboard bidets for eight airlines including JAL, Al Nippon Airways and Oman Air. They were also first to introduce hygienic touchless flushes and faucets, on the Boeing 787.

尽管这一过程已经历了50年的考验，但并不意味着它将一成不变。占据飞机厕所市场50%份额的日本Jamco公司已经开始为多家航空公司制造机上坐便器，并率先在波音787飞机上推出了卫生的非接触式冲水器和水龙头。

A spokesperson for the company told CNN: “There are constraints in terms of space, safety requirements, and stringent certifications, making it challenging to introduce new technologies in aircraft interiors.However, we are continuously conducting workshops and discussions with various stakeholders to explore next-generation interior products.” In other words – watch this (small, suction-operated) space.

公司发言人表示：“尽管空间、安全要求和严格认证等方面的限制给飞机内饰新技术的引入带来了挑战，但我们仍在与各利益相关方积极探讨和研发下一代内饰产品。”

Fresh air at 40,000 feet
四万英尺高空的清新空气

It wasn’t just travel restrictions that stopped people traveling when the pandemic started; for many, the idea of sitting in close proximity to strangers who might be harboring disease meant they had no intention of taking a flight, whether or not they were allowed.

新冠疫情初期，除了旅行限制外，与可能携带病毒的陌生人近距离接触也成为许多人拒绝乘坐飞机的原因之一。

That’s when airlines – which usually concentrate on publicizing their inflight entertainment and fancy seats – started talking about HEPA filters. These air filters – HEPA stands for “high efficiency particulate air”– are standard in two environments: aircraft and operating rooms. According to the US government’s Environmental Protection Agency, they can remove “at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles with a size of 0.3 microns.”

这时，航空公司开始大力宣传机上的HEPA过滤器。这些高效微粒空气过滤器在飞机和手术室中都是标配，能够去除至少99.97%的灰尘、花粉、霉菌、细菌以及任何0.3微米大小的空气颗粒。

While many people think the air on a plane is constantly blown around the cabin, Jones says that modern aircraft circulate air in a different way. “In the old days, aircraft used to take air from the engines, so it had to be cooled through through an air conditioning pack,” he says. But newer aircraft – such as the Boeing 787 – don’t use “engine bleed” air. Instead, they have onboard compressors – “one for each ECS, or environmental control system,” says Jones. They take air from an external source and run it through the compressor. The ECS then circulates the air through the cabin, refining it with HEPA filters.

虽然许多人认为飞机上的空气是在机舱内不断循环的，但Nigel Jones解释说，现代飞机的空气循环方式与此不同。他表示：“过去，飞机上的空气确实来自发动机，并需要通过空调机组进行冷却。但现在的新型飞机（如波音787）则采用机载压缩机从外部获取新鲜空气，并通过环境控制系统进行过滤和循环。”

The onboard air circulation of today isn’t just about keeping healthy – it also controls how passengers feel, especially on longhaul flights. “On a 787 the air is changed every three minutes – completely new air – and on the [Airbus] A350 it’s every two to three minutes, with precisely controlled temperature and humidity to make you feel fresh when you get to your destination,” says Jones.

这种先进的空气循环系统不仅确保了机舱内的空气清新和健康，还能为乘客提供更加舒适的飞行体验。Nigel Jones说：“在波音787飞机上，空气每三分钟就会完全更换一次。而在空客A350飞机上，空气每两到三分钟更换一次，并且温度和湿度都经过精确控制，让乘客在长途飞行中依然感觉清新舒适。”