Narrative:

On 06/wed/2001, mdw tower experienced a temporary power outage, which caused the resetting of all positions in the cabin attendant. On 06/wed/2001 at XA01 local time, the tower lost all frequencies. The controllers 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 frequency problems. These problems have consisted of, interference, continuous transmission, stuck mikes, and outages. The june wed outage of all frequencies was apparently caused by a voltage drop on the incoming power line. Mdw tower does not have a pcs/ups to ensure that a voltage drop will not lock up our voice switch system. Callback conversation with reporter revealed the following information: reporter alleges that the facility generator activates when the commercial power monitor recognizes a power drop that will not sustain all the tower communication equipment and frequencys. When commercial power is recognized as able to sustain all tower communication equipment, it switches back to commercial power. It was during the second commercial power drop and subsequent return to commercial power, that the vscs equipment 'froze', and was not immediately available to the controllers. The controller expressed concern for the lack of a ups system not being installed when the new tower was commissioned.

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Original NASA ASRS Text

Title: 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.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.