Amazon has been talking about delivering packages by drone for several years now, from an initial 2013 unveil to a public demonstration in 2017. As the company has worked to make package delivery by air a reality, it’s also been busy filing for patents on the process. The company has been granted a patent on a delivery drone that can respond to human gestures and vocal commands.

The patent, US9459620B1, covers how an unmanned drone might interact with and respond to humans it encounters while making a delivery. The abstract states:

[T]he management system may be configured to receive human gestures via the sensor device and, in response, instruct the propulsion device to affect an adjustment to the behavior of the unmanned aerial vehicle. Human gestures may include visible gestures, audible gestures, and other gestures capable of recognition by the unmanned vehicle.

The patent is accompanied by this amazing image.

Amazon’s patent describes a system in which a drone could observe various human gestures or voice commands to help it make a delivery. A person who waves their arms in a shooing gesture would be read as telling the drone to move away, while someone who makes an inviting motion might be indicating where the package should be left. The patent also covers various methods the drone might use to ascertain if a package should be left with someone, ranging from direct visual identification to an authentication sequence between the user’s smartphone and the drone itself. Amazon’s patent doesn’t contemplate how the drone would deal with false responses or griefing — which in this context would be people deliberately feeding the drone bad feedback to prevent or delay delivery. Given the realities of human nature, any proposed autonomous delivery system needs to be able to cope with bad information, too, not just positively identify an intended recipient.

Amazon clearly wants to move ahead with drone delivery, and a system that can parse and take human responses into account is going to be necessary for any kind of mainstream package delivery system, but it’s not clear when the company would be able to begin deliveries. FAA regulations forbid the use of commercial drones that aren’t controlled by line-of-sight operators, and some cities like NYC have strict laws governing where drones are allowed to fly. Until those barriers are resolved, don’t expect to get your packages by air — or by frantically flapping your arms at a passing drone.