Date: 201208
Local time of day: 0001-0600
Location: D21.TRACON, MI
Aircraft: EMB ERJ 135 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Descent
ATC / advisory: TRACON D21
Second aircraft: B737 Undifferentiated or Other Model
Reporter organization: Government
Reporter function: Departure; Approach
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Communication Breakdown
Anomaly: ATC Issue All Types; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Detector: Person Air Traffic Control
Result: General None Reported / Taken
Contributing factors: ATC Equipment / Nav Facility / Buildings
Primary problem: ATC Equipment / Nav Facility / Buildings

Narrative: [I was] working A for about 1/2 hour. From my first transmission I was having problems with the frequency. I repeated myself multiple times to the first aircraft on the frequency. I initially changed from main to standby transmitter; but as the problem persisted; I thought it was my headset. I asked C2 to get me a handset; and that seemed to help. As I continued working; the handset was apparently having the same problems; and I reported to my supervisor that the position itself seemed to have a transmitter problem. At the time; I considered the problem mainly an annoyance. A B737 checked in; and I initially slowed him to 190 KTS descend to 5;000. When the E135 checked on still fast; I changed my mind and re-restricted the B737 to 7;000. I honestly do not remember whether I thought he read that back or not. I was obviously more distracted by the transmitter problem than I had; at the time; believed. I know that I was missing some transmissions because I thought that I was on the frequency; but was not. I was also changing jacks and trying both the handset and my headset. Sometimes; when I tried to transmit; I could hear the side tone; sometimes I couldn't; so; it was very difficult to tell how much was being heard by anyone. When I saw the B737 descend through 7;000; I asked him what he was a cleared to and stopped him at 6;000. It was when I saw him descending that I realized that he might not have gotten the change to 7;000. I had already descended the E135 out of 6;000 to 4;000. I pointed out the B737 to the E135; and the E135 reported the B737 in sight. I told the E135 to maintain visual; but he didn't respond; and I figured that I had not actually transmitted. By that time; going through the motions to get the correct Visual Separation phraseology was moot; so I didn't repeat myself. The E135 reported a TCAS RA. Today; I discovered that another controller had a similar transmitter problem at the A position; but when the next controller plugged in the position seemed fine; so no equipment issue was reported. I am unaware of the time of this event; or whether there were any other previous issues. We hear every day that we must listen actively and cut down on distractions. I don't think that we could have more or better training on these issues. I wish that I could say I made sure everything was working in the system exactly. It should; but; obviously; I cannot. People here that have listened to the tapes tell me that I sounded fine; but I know that I was feeling a great deal of frustration about the frequency. I was trying so hard to troubleshoot; and just busy enough to not realize that it was the jacks themselves that were failing somehow. I wish that I would have known that there were previous issues with the position. I think that; as people review the scenario; you will think that the transmitter issue wasn't a factor in the specific loss of separation; all I can say is that it was; by far; my overwhelming concern; and it was therefore of paramount importance. An additional contributing factor was limited time on position recently and doing a great deal of training. I had asked a couple times for proficiency time; but that gets lost in the shuffle. Most importantly; even intermittent problems with a position can be serious; and should be investigated. I had a Supervisor and a Coordinator when all this was happening. I think that; because I sounded calm; they (and I) didn't realize how much difficulty I was having focusing on the traffic. It's easy to say that maybe one of the people nearby could have been more involved; but that's always easy to say in hindsight. Honestly; I think this comes down to an equipment issue that was a huge distraction. Get things fixed. When this does happen; don't try to work around it; no matter if the facility is short staffed and people are doing other things; or whatever excuse I might choose to insert.




Synopsis: D21 Controller described an unsafe condition when communications equipment was operating intermittently; distracting the reporter.