Narrative:

We have an approach light system for runway 23 that was installed approximately 6 yrs ago. Since then it has had chronic recurring problems, the most frequent of which pertains to the monitor/control panel. Constant 'caution' and 'failure' alarms have not been corrected even though 2 ucr's have been filed and our local airport facility personnel have dedicated many hours towards its repair. The problem apparently is caused by its design. Even though the monitor is unreliable at best we continue to operate the system as thought is normal. We assume that the system is operating unless a pilot report indicates otherwise. Pilots are not aware of the fact that the lights may fail without us knowing it. On dec/xx/92, the entire center portion of lights failed without any indication on the monitor. Many arrs landed in adverse WX during the previous evening and following morning. (Ceilings as low as 300 ft and reduced visibility due to fog.) pilots did not report any abnormalities, probably because they are distracted by higher priority tasks or don't recognize what a properly operating system looks like, or perhaps just could not see them. Considering the frequency at which actual failures do occur, I believe that this is a hazardous situation and will continue to post a threat to safety until 1) the system is redesigned to operate more reliably and with greater tolerances on the monitor, 2) the system is simplified for more reliability, and 3) the system is notamed unmonitored until the above conditions are accomplished.

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Original NASA ASRS Text

Title: COMPLAINT FROM CTLR THAT THE APCH LIGHT SYS HAS NOT BEEN WORKING PROPERLY SINCE INSTALLED.

Narrative: WE HAVE AN APCH LIGHT SYS FOR RWY 23 THAT WAS INSTALLED APPROX 6 YRS AGO. SINCE THEN IT HAS HAD CHRONIC RECURRING PROBS, THE MOST FREQUENT OF WHICH PERTAINS TO THE MONITOR/CTL PANEL. CONSTANT 'CAUTION' AND 'FAILURE' ALARMS HAVE NOT BEEN CORRECTED EVEN THOUGH 2 UCR'S HAVE BEEN FILED AND OUR LCL ARPT FACILITY PERSONNEL HAVE DEDICATED MANY HRS TOWARDS ITS REPAIR. THE PROB APPARENTLY IS CAUSED BY ITS DESIGN. EVEN THOUGH THE MONITOR IS UNRELIABLE AT BEST WE CONTINUE TO OPERATE THE SYS AS THOUGHT IS NORMAL. WE ASSUME THAT THE SYS IS OPERATING UNLESS A PLT RPT INDICATES OTHERWISE. PLTS ARE NOT AWARE OF THE FACT THAT THE LIGHTS MAY FAIL WITHOUT US KNOWING IT. ON DEC/XX/92, THE ENTIRE CTR PORTION OF LIGHTS FAILED WITHOUT ANY INDICATION ON THE MONITOR. MANY ARRS LANDED IN ADVERSE WX DURING THE PREVIOUS EVENING AND FOLLOWING MORNING. (CEILINGS AS LOW AS 300 FT AND REDUCED VISIBILITY DUE TO FOG.) PLTS DID NOT RPT ANY ABNORMALITIES, PROBABLY BECAUSE THEY ARE DISTRACTED BY HIGHER PRIORITY TASKS OR DON'T RECOGNIZE WHAT A PROPERLY OPERATING SYS LOOKS LIKE, OR PERHAPS JUST COULD NOT SEE THEM. CONSIDERING THE FREQUENCY AT WHICH ACTUAL FAILURES DO OCCUR, I BELIEVE THAT THIS IS A HAZARDOUS SIT AND WILL CONTINUE TO POST A THREAT TO SAFETY UNTIL 1) THE SYS IS REDESIGNED TO OPERATE MORE RELIABLY AND WITH GREATER TOLERANCES ON THE MONITOR, 2) THE SYSTEM IS SIMPLIFIED FOR MORE RELIABILITY, AND 3) THE SYS IS NOTAMED UNMONITORED UNTIL THE ABOVE CONDITIONS ARE ACCOMPLISHED.

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.