Narrative:

On nov/xx/92, I was working local control northwest (135.0). I had 1 aircraft touching down on runway 3L, 1 more on final, and 1 taxiing out for departure. Near the departure end of the runway I asked the taxiing cga X (an small transport) if he was ready for departure and he replied in the affirmative. I taxied him into position to hold as the other aircraft had not cleared the runway. As the first aircraft cleared, I cleared cga X for takeoff. No response. I cleared him again and still no response. The traffic on final was 3 mi from the runway now and closing quickly. I switched to backup transmitter and reclred cga X. No response. I then switched to the emergency jack and once again cleared cga X with traffic well within a 2 mi final. Cga X responded and a go around (or worse) was averted. This is not the first time a situation like this involving an aircraft on a runway has occurred. Other instances involve aircraft exiting with hold short instructions, unreadable clearance readbacks, not receiving aircraft acknowledgement of clrncs while the aircraft appears to be doing what he was told, aircraft attempting to call for taxi or clearance for over 15 mins and either not being able to hear ATC or ATC not able to hear him, and many others. We have attempted to document as many of these instances as we can, however, in busy traffic sits this is sometimes impossible. With as much traffic as dtw runs in complex sits involving 3 ground controls, 2 and sometimes 3 departure runways, 2 landing runways and ground control northwest's limited ramp and taxi areas for both taxiing and pushback aircraft, this is unacceptable and should not be ignored. Callback conversation with reporter revealed the following information: reporter states that frequency problems still exist on clearance delivery, ground control and local control frequencys. Airway facilities and at management aware of problem. Antennas have been relocated in an attempt to correct transmitter/receiver blind spots, but it still occurs. The problems started when they moved into the new tower last aug. This is an intermittent occurrence that impacts primarily light aircraft and some commuter aircraft. To the reporter's knowledge, there has not been any serious incidents except gars. The only way a controller can communicate with an aircraft when this occurs, is to utilize the emergency radio jacks. 2 ucr's have been filed so far. A second callback to reporter was made to see if the frequency problem still existed or if the transmitter/receiver antennas had been relocated to eliminate the blind spots. The reporter said that there has been no change, or little change in this condition. Reporter stated that sometimes it appears to be better, while other times it's worse. Although maintenance has been working on it, there basically has been no change since the report was submitted. The ucr filed has not been closed out.

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Original NASA ASRS Text

Title: CTLR CLAIMS THAT TWR XMITTERS AND RECEIVERS ARE INTERMITTENT WHEN ATTEMPTING TO WORK ACFT ON THE GND.

Narrative: ON NOV/XX/92, I WAS WORKING LCL CTL NW (135.0). I HAD 1 ACFT TOUCHING DOWN ON RWY 3L, 1 MORE ON FINAL, AND 1 TAXIING OUT FOR DEP. NEAR THE DEP END OF THE RWY I ASKED THE TAXIING CGA X (AN SMT) IF HE WAS READY FOR DEP AND HE REPLIED IN THE AFFIRMATIVE. I TAXIED HIM INTO POS TO HOLD AS THE OTHER ACFT HAD NOT CLRED THE RWY. AS THE FIRST ACFT CLRED, I CLRED CGA X FOR TKOF. NO RESPONSE. I CLRED HIM AGAIN AND STILL NO RESPONSE. THE TFC ON FINAL WAS 3 MI FROM THE RWY NOW AND CLOSING QUICKLY. I SWITCHED TO BACKUP XMITTER AND RECLRED CGA X. NO RESPONSE. I THEN SWITCHED TO THE EMER JACK AND ONCE AGAIN CLRED CGA X WITH TFC WELL WITHIN A 2 MI FINAL. CGA X RESPONDED AND A GAR (OR WORSE) WAS AVERTED. THIS IS NOT THE FIRST TIME A SIT LIKE THIS INVOLVING AN ACFT ON A RWY HAS OCCURRED. OTHER INSTANCES INVOLVE ACFT EXITING WITH HOLD SHORT INSTRUCTIONS, UNREADABLE CLRNC READBACKS, NOT RECEIVING ACFT ACKNOWLEDGEMENT OF CLRNCS WHILE THE ACFT APPEARS TO BE DOING WHAT HE WAS TOLD, ACFT ATTEMPTING TO CALL FOR TAXI OR CLRNC FOR OVER 15 MINS AND EITHER NOT BEING ABLE TO HEAR ATC OR ATC NOT ABLE TO HEAR HIM, AND MANY OTHERS. WE HAVE ATTEMPTED TO DOCUMENT AS MANY OF THESE INSTANCES AS WE CAN, HOWEVER, IN BUSY TFC SITS THIS IS SOMETIMES IMPOSSIBLE. WITH AS MUCH TFC AS DTW RUNS IN COMPLEX SITS INVOLVING 3 GND CTLS, 2 AND SOMETIMES 3 DEP RWYS, 2 LNDG RWYS AND GND CTL NW'S LIMITED RAMP AND TAXI AREAS FOR BOTH TAXIING AND PUSHBACK ACFT, THIS IS UNACCEPTABLE AND SHOULD NOT BE IGNORED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THAT FREQ PROBS STILL EXIST ON CLRNC DELIVERY, GND CTL AND LCL CTL FREQS. AIRWAY FACILITIES AND AT MGMNT AWARE OF PROB. ANTENNAS HAVE BEEN RELOCATED IN AN ATTEMPT TO CORRECT XMITTER/RECEIVER BLIND SPOTS, BUT IT STILL OCCURS. THE PROBS STARTED WHEN THEY MOVED INTO THE NEW TWR LAST AUG. THIS IS AN INTERMITTENT OCCURRENCE THAT IMPACTS PRIMARILY LIGHT ACFT AND SOME COMMUTER ACFT. TO THE RPTR'S KNOWLEDGE, THERE HAS NOT BEEN ANY SERIOUS INCIDENTS EXCEPT GARS. THE ONLY WAY A CTLR CAN COMMUNICATE WITH AN ACFT WHEN THIS OCCURS, IS TO UTILIZE THE EMER RADIO JACKS. 2 UCR'S HAVE BEEN FILED SO FAR. A SECOND CALLBACK TO RPTR WAS MADE TO SEE IF THE FREQ PROB STILL EXISTED OR IF THE XMITTER/RECEIVER ANTENNAS HAD BEEN RELOCATED TO ELIMINATE THE BLIND SPOTS. THE RPTR SAID THAT THERE HAS BEEN NO CHANGE, OR LITTLE CHANGE IN THIS CONDITION. RPTR STATED THAT SOMETIMES IT APPEARS TO BE BETTER, WHILE OTHER TIMES IT'S WORSE. ALTHOUGH MAINT HAS BEEN WORKING ON IT, THERE BASICALLY HAS BEEN NO CHANGE SINCE THE RPT WAS SUBMITTED. THE UCR FILED HAS NOT BEEN CLOSED OUT.

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.