iPadOS 11.3 (build 15E216) is an official Apple over-the-air update for the iPad Air (WiFi), released on 2018-03-29T17:05:44Z. The update package is 1.23 GB. This is a delta (partial) update that requires 10.3.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 0af58415f05227aba4c42c80a436442ad5382992.zip.