Aircraft that are certificated for the use of the autopilot for approach, normally have, in the AFM, the certification data mentioned, including the maximum altitude loss allowed by the design.
Pretty basic info, and I'm surprised it would baffle anyone, except of course, if they don't teach this in ground school anymore....and more than likely many airlines do not.
In addition, sometimes this information can be found in the Type Certificate Data Sheets....older models, mostly.