iPadOS 9.1 (build 13B143) is an official Apple over-the-air update for the iPad Air 2 (WiFi), released on 2015-10-21T17:15:58Z. The update package is 1.12 GB. This is a delta (partial) update that requires 8.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 5c075ac7c2d32805ef3509aa8e00b7f98feba83e.zip.