Amazon’s drone delivery program might be part of an even bigger idea, one that involves huge fulfillment centers floating above cities.

An Amazon patent, found by CB Insights analyst Zoe Leavitt, shows an “airborne fulfillment center utilizing unmanned aerial vehicles for delivery,” one of the wackiest ideas to come out of the e-commerce giant.

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In the patent, Amazon shows a massive zeppelin above a city, deploying delivery drones. The zeppelin is stocked full of packages and re-supplied by smaller airships, which also transport recharged drones, workers, and packages.

The main airship would be 45,000 feet in the air, higher than most commercial flights. Drones would descend from the airship, saving a lot of energy, and return to smaller airships located outside of the city for refueling.

Amazon’s plan certainly removes the need for purchasing large warehouses in major cities, where a lease can cost thousands of dollars a month. On the downside, Amazon would need to seek approval from the Federal Aviation Administration, which is already unhappy with its drone delivery program.

A zeppelin filled with books…what could go wrong?

The economics of a floating zeppelin fulfillment center have not been disclosed in the patent. The most expensive part, we assume, would be the back-and-forth trips from smaller airships to the main zeppelin, as the drones are most likely battery powered.

That sounds cheap compared to the myriad of solutions Amazon currently uses to make all of its deliveries arrive on time. The e-commerce giant recently invested in 15 airplanes, showing it is willing to try anything to lower the delivery time.

Like all patents, we have to assume that Amazon isn’t going to work on this, and is only patenting it to secure the idea. While it would be nice to see Amazon’s sending drones from a floating zeppelin, it doesn’t seem like the most likely new program to come from the Seattle-based company.