Two thoughts about this method:

1. They assume a constant base frequency that only shifts because of the Doppler effect, but I'd argue you can get more precise results if you consider frequency changes due to flight maneuvers, changing speed etc., too.

2. You could combine this method with ENF analysis to narrow down the date and/or time.

https://en.wikipedia.org/wiki/Electrical_network_frequency_analysis

https://www.youtube.com/watch?v=e0elNU0iOMY (6 min)