During your career as a pilot you will see more advanced navigation systems in the airplanes you fly. Systems like Radio Magnetic Indicators, Horizontal Situation Indicators and navigation systems like RNAV, LORAN (now obsolete) and satellite navigation systems as GPS.
The document below is from: Enhanced LORAN by Sherman Lo and Benjamin Peterson, Stanford GPS Lab, with contributions from the FAA Loran Evaluation Team.
Excerpt from the document:
Enhanced Loran is designed to provide back up/redundancy to GPS/GNSS in safety critical applications. Loran for tactical purposes is possible with efficient transmitters. Loran is difficult, but not impossible to spoof/jam. But its future is still uncertain.
To continue reading see the pdf below: