We just decided in December to decommission Landsat 5 because of too many instrument failures. (sciencemag.org)
To replace the missing AMSR - E-derived sea ice maps after the AMSR - E instrument failure on October 4, 2011, we apply the same algorithm (ARTIST sea ice) to the 91 GHz channels of the SSMIS instrument (DMSP satellites), the main difference being the change of frequency from 89 GHz (AMSR - E) to 91 GHz (SSMIS). (iup.uni-bremen.de)
These errors can be straight - up mistakes in transcription, instrument failure, or data corruption etc., but these are generally easy to spot and so I won't dwell on this class of error. (realclimate.org)