iPadOS 11.4 (build 15F5077a) is an official Apple over-the-air update for the iPad Air (WiFi), released on 2018-05-14T17:16:41Z. The update package is 222.82 MB. This is a delta (partial) update that requires 11.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 7a5de4bc9f0b2763df0d0a7662f3f260c3d20baf.zip.