iPadOS 9.9.11.2.1 (build 15C153) is an official Apple over-the-air update for the iPad Air (Cellular), released on 2017-12-13T18:03:46Z. The update package is 1.49 GB. This is a delta (partial) update that requires 8.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 02d0f3d45be26c69283bb014375de00aedb7a833.zip.