This white paper discusses the reality of interference threats to the global positioning systems (GPS) and how they could potentially jeopardise much of the US infrastructure if the national decision-makers fail to address the situation with a full set of countermeasures.

The paper provides background on satellite navigation and describes the impact of the dangerous personal protection devices (PPDs) and other disruptive radio frequency interference (jamming), suggesting needed action.

The PNT Advisory Board believes that countermeasures and actions must be urgently developed and discusses the need for alternate navigation systems such as eLoran or a backup system currently being configured by the Federal Aviation Administration (FAA).