iPadOS 9.1 (build 13B143) is an official Apple over-the-air update for the iPad Air 2 (Cellular), released on 2015-10-21T17:15:59Z. The update package is 1.1 GB. This is a delta (partial) update that requires 8.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: db01234252064c27ffe5e64e73103888ef3a2b93.zip.