你有足够的勇气踏上 “空中出租车”吗？那么，如果这辆飞车连驾驶员都没有呢？事实上，建造出世界首辆无人驾驶的空中出租车正是一些公司期望达成的目标。

You know the feeling. You're stuck in bumper-to-bumper traffic. It's going to be hours before you get home. As we know all too well, congestion is one of the downsides of modern city living. Don't you wish you could just take to the skies and soar above it all in a helicopter? 

Well, wish no more. Right now, the race is on to release the first commercially viable sky taxi. No longer will personal air travel be the preserve of the super wealthy, say optimistic tech entrepreneurs. There's just one catch: how do you feel about having no pilot? 

For brave passengers, the city of Dubai plans to roll out rides on their pilotless drone taxi project by the end of this year. You can buckle up and share the ride with one other passenger in their 18-rotor craft, developed by German start-up Volocopter, with a top speed of 100km/h and a flight time of around 30 minutes. 

If you have more friends, French aviation company Airbus are working on a drone which can carry four to six customers. Or if you prefer your own company, Chinese firm Ehang are pioneering a single-seater drone, which stays airborne for 23 minutes. 

Ride-hailing company Uber also want a piece of the action. They say drones like this are the "future of on-demand urban air transportation". They recently poached NASA chief technologist Mark Moore to help them develop a drone taxi. And he claims it won't cost the earth. Moore told the BBC that with three or four passengers sharing, it would be "very similar to what an UberX [car] costs today".

So far so good. But naturally, a number of questions remain. On the technical side, there's the problem of batteries. A 23-minute flight could get you across town, but how and where does the battery recharge?

And regulations are a challenge too. US authorities require aircraft to carry at least 20 minutes of spare fuel. If you only have 23 or even 30 in total, that leaves very little leeway. Control of access to flight paths will also need to be worked out.

Even if these issues are tackled successfully, there's still the biggie: safety. Will passengers really be willing to put their lives in the hands of a flying robot? Winning the trust of the regulators and the public may take time. But when they do, well, the sky's the limit.