iPadOS 11.3 (build 15E216) is an official Apple over-the-air update for the iPad Air (China), released on 2018-03-29T17:06:00Z. The update package is 704.17 MB. This is a delta (partial) update that requires 11.0.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 68a67ee5926160d05361c76c2ade6f11dfcdc186.zip.