iPadOS 11.3 (build 15E216) is an official Apple over-the-air update for the iPad Air (China), released on 2018-03-29T17:05:59Z. The update package is 1.23 GB. This is a delta (partial) update that requires 10.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 3c046fc396ae97b8e32fdb7d0e7c76121167611e.zip.