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 264 MB. This is a delta (partial) update that requires 9.0.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 7fdce3a8f9416fc6e7d55013b33f9022f3d3d375.zip.