TAXIING TOWARDS the runway, the propeller stops turning as your correspondent pulls the throttle back to await take-off. On a single-engine light aircraft, that is usually a worrying sign of engine failure. Yet this plane is powered by an electric motor and, just as when you come to a halt in a Tesla, the motor stops until it is needed again. On advancing the throttle the propeller springs back to life(重新活跃起来) and the aircraft is soon briskly climbing, in an eerily(怪异地，令人不安地) quiet manner.
滑行至跑道时，螺旋桨停止了转动——记者正将油门拉回，等待起飞。在单引擎轻型飞机上，这通常是发动机故障的令人担忧的信号。然而，这架飞机由电动机驱动，就像特斯拉停车时一样，电机会停止运转，直到再次需要它。推进油门后，螺旋桨重新启动，飞机很快轻快地爬升，以一种异常安静的方式。
The two-seater Pipistrel Velis Electro is the first electric aircraft to be certified(获得认证的) for pilot training. Besides its low noise, it has other unusual features. Instead of the lengthy series of engine checks a combustion-engine plane requires before take-off, the Electro is ready to go with the flick of four switches(只需拨动四个开关). Since it has few moving parts, it is also cheaper to maintain. And without directly producing any nasty(有害的，令人不快的) emissions it can claim to be green, especially if recharged with renewable power. Topping up the battery takes just over an hour.
双座Pipistrel Velis Electro是首款获准用于飞行员培训的电动飞机。除了低噪音，它还有其他不寻常的特点。与传统燃油飞机起飞前需要一系列冗长的发动机检查不同，Electro只需拨动四个开关即可准备就绪。由于活动部件少，维护成本也更低。而且，由于不直接产生任何有害排放物，它可以自称环保，尤其是使用可再生能源充电时。充满电池只需一个多小时。
Returning to land back at Blackbushe Airport, south-west of London, the larger expanse of Farnborough Airport looms(隐约出现，逼近) nearby. At its biennial(两年一次的) air show, which opened on July 20th, sustainable flying was high on the agenda(重要议程，优先事项). Aviation accounts for around 2.5% of anthropogenic CO2 emissions, although overall its contribution to climate change is reckoned to be greater, since high-flying jets produce other heat-trapping emissions, such as nitrogen oxides.(航空业约占人为二氧化碳排放量的2.5%，但总体对气候变化的贡献被认为更大，因为高空喷气机还产生其他吸热排放物。) These are proving particularly tough to clean up. As a consequence, the aviation industry’s pledge(承诺，保证) to reach net-zero emissions(净零排放) by 2050 will probably be missed.
返回伦敦西南部的布莱克布什机场降落时，附近法恩伯勒机场更广阔的场地隐约可见。在7月20日开幕的两年一度的航展上，可持续飞行是重要议题。航空业约占人为二氧化碳排放量的2.5%，但总体而言，其对气候变化的贡献被认为更大，因为高空飞行的喷气机还会产生其他吸热排放物，如氮氧化物。这些排放物尤其难以清除。因此，航空业到2050年实现净零排放的承诺很可能无法兑现。