iPadOS 11.4 (build 15F5061d) is an official Apple over-the-air update for the iPad Air (Cellular), released on 2018-05-01T17:05:34Z. The update package is 171.4 MB. This is a delta (partial) update that requires 11.4 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 71799c49e83d5f945d11b3a40ffc21ee6e33d64d.zip.