Airplane Depreciation Type

I feel like I remember it being straight line over 20 or 25 years, did you try google?

Yes looking for the asset class or do i use "Other"?

It depends a lot on a/c type and usage. Light planes operating under FAR part 91 would probably be 5 year MACRS… Rules become more complex based on type because component parts; airframe, engine, avionic, can have different asset values and lives.

So, what is it, and how is it being used?

Per Thomson Reuters Checkpoint Depreciation Quickfinder Handbook, 2022 tax year, on page 2-17, under special (bonus) depreciation, within Tab 2, which is MACRS: Long Production Period Property and Aircraft: Qualified property for bonus depreciation includes long production period property and certain noncommercial aircraft placed in service before 2028. The following bonus depreciation rates apply to such property: 2018 to 2023 (placed in service) is a 100% bonus depreciation rate. This book is thick, and I do not have the time to go through the whole book to look for more information concerning aircraft,  as I am quite busy, so do your due diligence and research this further, and maybe it may or may not be of help to you. Just my opinion.

https://www.irs.gov/pub/irs-pdf/p946.pdf#page=97