Narrative:

I had multiple unusual things happening. Over the top of the airport and under the downwind; a aircraft was orbiting at 5;500 ft. I also had an IFR departure that departed VFR for an IFR pickup who was lost communications; all of our primary radios failed; we had to go to back ups. The back up radios were running on battery power so I also was testing and configuring my tunable in case I lost my back ups. Traffic started picking up; I knew it was about to get busy. As the traffic was picking up; I decided my sequence for a SF34 coming from the west. I pointed the aircraft out to the tyson position and began descending him reference the plane I was putting him behind. I called the traffic he would land behind; he reported it in sight and was instructed to maintain visual separation from the traffic. He reported the airport in sight and was cleared for a visual approach to runway 33 reference the preceding aircraft landing runway one. As the SF34 was about to cross the final; I realized I put him on the wrong frequency. An E170 was cleared for the mt. Vernon visual runway 1 approach and was just to the south of the SF34; northbound; descending out of 1;800 ft. I immediately called traffic and it was reported in sight. I said maintain visual separation from that traffic. I tried to call the E170 to tell him about an aircraft on a converging course maintaining visual separation; but the E170 was already over to the tower. I instructed the SF340 to maintain 2;000 ft and continue eastbound across the flight path of the E170 and when the spacing was right; I turned the SF34 back to the airport and cleared him again for the visual approach to runway 33. Visual separation was not properly applied here because though I could immediately communicate with one of the aircraft; I did not inform the other aircraft on a converging course. I made a mistake and I know exactly what I did. Recommendation; open the final control position when unusual events are happening. It would have made a real difference in the situation.

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Original NASA ASRS Text

Title: PCT Controller described a loss of separation event involving traffic inbound to DCA when failing to apply proper visual separation criteria because one aircraft had been transferred to the Tower and traffic exchanges could not be completed.

Narrative: I had multiple unusual things happening. Over the top of the airport and under the downwind; a aircraft was orbiting at 5;500 FT. I also had an IFR departure that departed VFR for an IFR pickup who was lost communications; all of our primary radios failed; we had to go to back ups. The back up radios were running on battery power so I also was testing and configuring my tunable in case I lost my back ups. Traffic started picking up; I knew it was about to get busy. As the traffic was picking up; I decided my sequence for a SF34 coming from the west. I pointed the aircraft out to the Tyson position and began descending him reference the plane I was putting him behind. I called the traffic he would land behind; he reported it in sight and was instructed to maintain visual separation from the traffic. He reported the airport in sight and was cleared for a visual approach to Runway 33 reference the preceding aircraft landing Runway One. As the SF34 was about to cross the final; I realized I put him on the wrong frequency. An E170 was cleared for the Mt. Vernon Visual Runway 1 Approach and was just to the south of the SF34; northbound; descending out of 1;800 FT. I immediately called traffic and it was reported in sight. I said maintain visual separation from that traffic. I tried to call the E170 to tell him about an aircraft on a converging course maintaining visual separation; but the E170 was already over to the Tower. I instructed the SF340 to maintain 2;000 FT and continue eastbound across the flight path of the E170 and when the spacing was right; I turned the SF34 back to the airport and cleared him again for the visual approach to Runway 33. Visual separation was not properly applied here because though I could immediately communicate with one of the aircraft; I did not inform the other aircraft on a converging course. I made a mistake and I know exactly what I did. Recommendation; open the Final Control position when unusual events are happening. It would have made a real difference in the situation.

Data retrieved from NASA's ASRS site as of April 2012 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.