Impairment Vs Unplanned Depreciation

Hello All

Please can someone share your thoughts on Impairments Vs Unplanned Depreciation? I know the fundamental definitions of these two, but want to know whether the unplanned depreciation will have same affect like Impairment in terms of changing the financial information on asset?

Because we couldn’t implement the Impairment functionality and thinking to use Unplanned Depreciation standard API to mass upload the unplanned depreciation values into Oracle to reduce the asset Net Book Value (NBV)

Any helpful info would be much appreciate

Thanks