Non-adherence to telecommunication procedures 8 035032 Instrument failure 7 035032 Missing value 15 035032 Lack of consumables 6 035032 Cause of missing data 1 Shortage of qualified staff to man stations 5 035032 Non-implementation or maintenance of required RBSN density 4 035032 Data groups missing due to radio fading 1 035032 Data groups missing due to outage of circuit 3 035032 2014-09-03T09:56:32.371Z Data groups missing due to outage of centre 2 035032 Some observing programmes ceased 9 035032