Degradation of signals and operation failures of radio engineering   satellite systems during geospace disturbances accompanied by abrupt changes   in the geomagnetic field
  During strong magnetic storms, the errors of determination of the range, frequency Doppler shift and angles of arrival of transionospheric radio signals exceeds the one for magnetically quiet days by one order of magnitude as a minimum. This can be the cause of performance degradation of current satellite radio engineering navigation, communication and radar systems as well as of superlong-baseline radio interferometry systems. The relative density of phase slips at mid-latitudes exceeds its mean value for magnetically quiet days at least by the order of 1 or 2, that makes a few percent of the total density of GPS observations. Furthermore, the level of phase slips for the GPS satellites located at the sunward side of the Earth was 5-10 times larger compared to the opposite side of the Earth. 
E. L. Afraimovich (Institute of Solar-Terrestrial Physics, Russian)