iPadOS 9.1 (build 13B137) is an official Apple over-the-air update for the iPad Air 2 (Cellular), released on 2015-10-12T16:56:54Z. The update package is 1.38 GB. This is a delta (partial) update that requires 9.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 64c2a7828463f8694bacaefc2ff25537d816862c.zip.