The trial is currently being run with just two customers, although Amazon plans to expand that to dozens in the coming months and, eventually, hundreds. Its aim is to gather data that can subsequently be used to improve the safety and reliability of the service and its systems.
The drones being used are electrically powered, fully autonomous and are guided by GPS. Similar to those unveiled by Amazon towards the end of last year, they have a range of 15 mi (24 km) and, when making deliveries, fly at an altitude of around 400 ft (122 m) at speeds of up to 55 mph (88 km/h). Packages of up to 5 lb (2.3 kg) in weight can be carried.
As per the agreed parameters of the trial, the drones are currently only permitted to be used during daylight hours, in low winds and with good visibility. They can't currently be flown when it is raining, windy or icy, but Amazon says these restrictions will be loosened as the collected trial data makes it reasonable to do so.
When one of the trial customers makes a Prime Air order, it is relayed to a Prime Air fulfilment center nearby. Here, the product is loaded into a box and onto one of the drones, which is transported outside of the fulfilment center building on a track.
Once cleared for launch, the drones take off, fly to their destination, land and return to the center without manual input. As the delivery is made, customers receive an alert on a mobile device to notify them of its arrival, after which the drone lands, releases the package and takes off again to return to the fulfilment center.
As you'd expect, Amazon is making very clear that safety is paramount. The drones are said to have been built with multiple redundancies so as to minimize the chance of them falling out of the sky, and so-called "sense and avoid" technology keeps them away from anything they could damage, or that could damage them, be that on the ground or in the air.
Amazon intends to roll out Prime Air as a delivery option around the world and says it is working with regulators and policymakers in various countries to do so. The firm says it will deploy the service when and where it has the regulatory support needed to do so safely.
The video below provides an overview of the Prime Air trial.