Narrative:

I arrived in the tower cabin attendant for my evening shift; and began working ground control. We were on a west flow (runway 28's). In my scan; I found that the terminal doppler WX radar (tdwr) ribbon display had no runway assignments whatsoever (ie; all lines below the ctrfield wind were blank. In other words; there was no 28LA; 28LD; 28RA; 28RD lines). My guess is that it had been in that condition the entire previous shift. With this setup; if microbursts or gust fronts would be occurring within the airport environment; we would not automatically receive alerts. Hence; the pilot would not hear about these unsafe conditions from us. Unfortunately; this latent error continues to occur on a regular basis. It appears that it is related to one or more of my colleagues inappropriately 'editing' the runway assignment; rather than 'selecting' (the already programmed) runway assignment. Part of the problem is the design of the equipment. Runway configns can be easily edited by any controller or supervisor. Unfortunately; they can easily do them incorrectly. When done; it will 'appear' correct on the tdwr display (ie; appropriate runways will 'appear' selected); but the remote ribbon display will be missing the crucial elements that generate the alerts (the 28LA; 28LD; 28RA; and 28RD elements). Part of the problem is education. If everyone is going to have access to the programming features; they need to be educated as to how to program it! Part of the problem is the alert path. The ribbon display alerts are now routed via the ids computer displays to all position. The confign (ie; the 28LA; 28LD; 28RA; 28RD lines) are not seen on the ids computer displays -- until an actual alert is generated (assuming the ribbon display has been appropriately configured). Hence 'out of sight; out of mind' comes into play. Part of the problem is ergonomics. The lone ribbon display is at the cabin attendant supervisor (cs) position and; therefore; out of the normal scan of the local control; ground control and clearance delivery position. Part of the problem is staffing. The lone ribbon display is at the tower cabin attendant supervisor position. With the minimal supervisory staff that we have; rarely is the cabin attendant supervisor position ever staffed these days. Another aspect to this latent error is inappropriate selection of runways. This typically occurs after a runway change; in which the tdwr confign had been correctly set; but forgotten to be changed. In this case; if an alert is generated; it will be for the incorrect runway direction; and the controller will have wrong alert data. Tdwr configns should be password protected; allowing only runway selections (of previously set up configns). Tdwr configns should be; if at all possible; set in such a manner as to never need changed. Part of the problem is a misunderstanding or lack of concern about latent error. This has gone on a very long time but exacerbated in our new tower cabin attendant design.

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Original NASA ASRS Text

Title: CMH CTLR EXPRESSED CONCERN REGARDING THE FACILITY'S USE OF THE TERMINAL DOPPLER WEATHER RADAR (TDWR); CITING SEVERAL FACTORS AS CONTRIBUTORY.

Narrative: I ARRIVED IN THE TWR CAB FOR MY EVENING SHIFT; AND BEGAN WORKING GND CTL. WE WERE ON A W FLOW (RWY 28'S). IN MY SCAN; I FOUND THAT THE TERMINAL DOPPLER WX RADAR (TDWR) RIBBON DISPLAY HAD NO RWY ASSIGNMENTS WHATSOEVER (IE; ALL LINES BELOW THE CTRFIELD WIND WERE BLANK. IN OTHER WORDS; THERE WAS NO 28LA; 28LD; 28RA; 28RD LINES). MY GUESS IS THAT IT HAD BEEN IN THAT CONDITION THE ENTIRE PREVIOUS SHIFT. WITH THIS SETUP; IF MICROBURSTS OR GUST FRONTS WOULD BE OCCURRING WITHIN THE ARPT ENVIRONMENT; WE WOULD NOT AUTOMATICALLY RECEIVE ALERTS. HENCE; THE PLT WOULD NOT HEAR ABOUT THESE UNSAFE CONDITIONS FROM US. UNFORTUNATELY; THIS LATENT ERROR CONTINUES TO OCCUR ON A REGULAR BASIS. IT APPEARS THAT IT IS RELATED TO ONE OR MORE OF MY COLLEAGUES INAPPROPRIATELY 'EDITING' THE RWY ASSIGNMENT; RATHER THAN 'SELECTING' (THE ALREADY PROGRAMMED) RWY ASSIGNMENT. PART OF THE PROB IS THE DESIGN OF THE EQUIP. RWY CONFIGNS CAN BE EASILY EDITED BY ANY CTLR OR SUPVR. UNFORTUNATELY; THEY CAN EASILY DO THEM INCORRECTLY. WHEN DONE; IT WILL 'APPEAR' CORRECT ON THE TDWR DISPLAY (IE; APPROPRIATE RWYS WILL 'APPEAR' SELECTED); BUT THE REMOTE RIBBON DISPLAY WILL BE MISSING THE CRUCIAL ELEMENTS THAT GENERATE THE ALERTS (THE 28LA; 28LD; 28RA; AND 28RD ELEMENTS). PART OF THE PROB IS EDUCATION. IF EVERYONE IS GOING TO HAVE ACCESS TO THE PROGRAMMING FEATURES; THEY NEED TO BE EDUCATED AS TO HOW TO PROGRAM IT! PART OF THE PROB IS THE ALERT PATH. THE RIBBON DISPLAY ALERTS ARE NOW ROUTED VIA THE IDS COMPUTER DISPLAYS TO ALL POS. THE CONFIGN (IE; THE 28LA; 28LD; 28RA; 28RD LINES) ARE NOT SEEN ON THE IDS COMPUTER DISPLAYS -- UNTIL AN ACTUAL ALERT IS GENERATED (ASSUMING THE RIBBON DISPLAY HAS BEEN APPROPRIATELY CONFIGURED). HENCE 'OUT OF SIGHT; OUT OF MIND' COMES INTO PLAY. PART OF THE PROB IS ERGONOMICS. THE LONE RIBBON DISPLAY IS AT THE CAB SUPVR (CS) POS AND; THEREFORE; OUT OF THE NORMAL SCAN OF THE LC; GC AND CD POS. PART OF THE PROB IS STAFFING. THE LONE RIBBON DISPLAY IS AT THE TWR CAB SUPVR POS. WITH THE MINIMAL SUPERVISORY STAFF THAT WE HAVE; RARELY IS THE CAB SUPVR POS EVER STAFFED THESE DAYS. ANOTHER ASPECT TO THIS LATENT ERROR IS INAPPROPRIATE SELECTION OF RWYS. THIS TYPICALLY OCCURS AFTER A RWY CHANGE; IN WHICH THE TDWR CONFIGN HAD BEEN CORRECTLY SET; BUT FORGOTTEN TO BE CHANGED. IN THIS CASE; IF AN ALERT IS GENERATED; IT WILL BE FOR THE INCORRECT RWY DIRECTION; AND THE CTLR WILL HAVE WRONG ALERT DATA. TDWR CONFIGNS SHOULD BE PASSWORD PROTECTED; ALLOWING ONLY RWY SELECTIONS (OF PREVIOUSLY SET UP CONFIGNS). TDWR CONFIGNS SHOULD BE; IF AT ALL POSSIBLE; SET IN SUCH A MANNER AS TO NEVER NEED CHANGED. PART OF THE PROB IS A MISUNDERSTANDING OR LACK OF CONCERN ABOUT LATENT ERROR. THIS HAS GONE ON A VERY LONG TIME BUT EXACERBATED IN OUR NEW TWR CAB DESIGN.

Data retrieved from NASA's ASRS site as of May 2009 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.