At least 10 FAA-approved pilot programs for various drone initiatives—some likely including package delivery—are slated to start by May. Separately, industry and government officials have indicated that Amazon, widely considered one the most aggressive and furthest advanced applicants, is pushing for safety approval of detailed drone designs, as well as precise operating rules.

Amazon officials declined to provide details. But Gur Kimchi, vice president of the company’s package-delivery organization called Prime Air, was hopeful that necessary approvals would be secured by 2019. Responding to questions on the sidelines of the conference about probable locations and timelines to initiate delivery flights, he repeatedly said “ask me next year.”