iPadOS 11.3 (build 15E216) is an official Apple over-the-air update for the iPad Air (Cellular), released on 2018-03-29T17:05:49Z. The update package is 1.24 GB. This is a delta (partial) update that requires 10.0.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 5f2a7a2dfb780d967131fc4adde0a493582265d4.zip.