iPadOS 11.4 (build 15F79) is an official Apple over-the-air update for the iPad Air (Cellular), released on 2018-05-29T17:13:13Z. The update package is 214.8 MB. This is a delta (partial) update that requires 11.3.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 02f00af93d11a91142553e1d583767fbdbeccdae.zip.