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 1.06 GB. This is a delta (partial) update that requires 8.4 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: f5415bedb3e171c8b51f939ccd874fb015a0f49c.zip.