open source mobile communications in the context of search and rescue

Hi, we are looking for some help creating open source mobile communication infrastructure in the context of a search and rescue (SAR) mission at sea. We would like to use the osmocom stack as sensing and communication infrastructure at sea. How precise is the timing advance for localization? Neels mentioned that "modern" mobile stations equipped with a GPS receiver can report the location to the operator. Could you point me to the right standard? Is there any reliable and open source tooling to determine the direction of the signal with multiple receivers (e.g. SDRs) in close proximity? You can find out more about the project here: https://www.hs-augsburg.de/searchwing/ Sorry for the mostly German content. Thanks for your help! Best Regards Philipp Borgers