I recently wanted to re-test my aerobic threshold, but my training peaks trial ran out. I decided to make the most of all my newly-found time at home and made a tool to calculate cardiac drift from a workout.
In case anyone else has a use for it, here it is online: https://douglas-watson.github.io/aet-calc/.
Drop a TCX file from your last AeT test run onto the page. It will plot your effort, then you can select the area over which to calculate Pa:Hr drift. As far as I understand, if you get a drift value close to 5%, you ran close to AeT. A value much above 5% means you ran faster than AeT, and a value much below 5% means you ran below AeT.
Let me know if it needs improvements! I’ve only tested with Garmin and Fitbit files.