MDW TWR CTLR CONCERNED WITH TWR FREQ AND VOICE SWITCHING AND CTL SYS (VSCS) FAILURE DUE TO COMMERCIAL POWER FLUCTUATIONS.

Narrative

ON 06/WED/2001; MDW TWR EXPERIENCED A TEMPORARY POWER OUTAGE; WHICH CAUSED THE RESETTING OF ALL POSITIONS IN THE CAB. ON 06/WED/2001 AT XA01 LOCAL TIME; THE TWR LOST ALL FREQUENCIES. THE CTLRS WERE FORCED TO OPERATE ON THE BACK-UP TRANSCEIVERS FOR 32 MINS. THE BACK UPS HAVE LIMITED RANGE AND WERE INTERFERING WITH EACH OTHER. THERE HAVE BEEN NUMEROUS ENTRIES ON THE DAILY OPERATING LOGS; CARRYOVER AND NEW; CONCERNING FREQ PROBS. THESE PROBS HAVE CONSISTED OF; INTERFERENCE; CONTINUOUS XMISSION; STUCK MIKES; AND OUTAGES. THE JUNE WED OUTAGE OF ALL FREQUENCIES WAS APPARENTLY CAUSED BY A VOLTAGE DROP ON THE INCOMING POWER LINE. MDW TWR DOES NOT HAVE A PCS/UPS TO ENSURE THAT A VOLTAGE DROP WILL NOT LOCK UP OUR VOICE SWITCH SYSTEM. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR ALLEGES THAT THE FAC GENERATOR ACTIVATES WHEN THE COMMERCIAL POWER MONITOR RECOGNIZES A POWER DROP THAT WILL NOT SUSTAIN ALL THE TWR COM EQUIP AND FREQS. WHEN COMMERCIAL POWER IS RECOGNIZED AS ABLE TO SUSTAIN ALL TWR COMMUNICATION EQUIP; IT SWITCHES BACK TO COMMERCIAL POWER. IT WAS DURING THE SECOND COMMERCIAL POWER DROP AND SUBSEQUENT RETURN TO COMMERCIAL POWER; THAT THE VSCS EQUIP 'FROZE'; AND WAS NOT IMMEDIATELY AVAILABLE TO THE CTLRS. THE CTLR EXPRESSED CONCERN FOR THE LACK OF A UPS SYS NOT BEING INSTALLED WHEN THE NEW TWR WAS COMMISSIONED.