Narrative:

I was working departure control position. There was weather affecting our normal departure routes to the west. I had 2 routes available to me (normally 4); and they had a 10 miles in-trail restrictions on them. MD80 departed a 160 degree heading and climbing to 10;000 ft. When he was about 7 miles south I turned him east (090 heading). At that point he informed me he was having aircraft issues and wanted to level at a lower altitude because he might need to return to land as an in-flight-emergency. I stopped him at 6;000 ft because of traffic. I displayed the aircraft tag to the feeder positions; so they would be aware he was going to stay at 6;000 ft and possibly return to land. I leaned over to the adjacent controller and pointed the aircraft out since I was about to enter his airspace. I continued working the other departures and coordinated with another position for a hand off. As I turned the MD80 north to return; he informed me he had a B737 in sight. At that point I noticed the DR3 controller had climbed the B737 through the altitude of the MD80 at 6;000 ft. I told the MD80 to maintain visual separation from the B737. By then separation was lost. The B737 was a departure off an adjacent airport being controlled by DR2/3; heading 130 and climbing to 5;000 ft. Dr 2/3 is suppose to stay at 5;000 ft and only climb when clear of DR1's traffic. The procedure is in place to separate DR1 traffic from DR2/3 traffic works today. The DR2/3 controller just needs to observe DR1's traffic before climbing out of 5;000 ft.

Related reports:

Google
 

Original NASA ASRS Text

Title: TRACON Controller described a conflict event involving an air carrier returning to the departure airport due to equipment problems and an air carrier departure from an adjacent airport. Failed internal communications were indicated as the causal factor.

Narrative: I was working Departure Control position. There was weather affecting our normal departure routes to the west. I had 2 routes available to me (normally 4); and they had a 10 miles in-trail restrictions on them. MD80 departed a 160 degree heading and climbing to 10;000 FT. When he was about 7 miles south I turned him east (090 heading). At that point he informed me he was having aircraft issues and wanted to level at a lower altitude because he might need to return to land as an In-Flight-Emergency. I stopped him at 6;000 FT because of traffic. I displayed the aircraft tag to the Feeder positions; so they would be aware he was going to stay at 6;000 FT and possibly return to land. I leaned over to the adjacent controller and pointed the aircraft out since I was about to enter his airspace. I continued working the other departures and coordinated with another position for a hand off. As I turned the MD80 north to return; he informed me he had a B737 in sight. At that point I noticed the DR3 Controller had climbed the B737 through the altitude of the MD80 at 6;000 FT. I told the MD80 to maintain visual separation from the B737. By then separation was lost. The B737 was a departure off an adjacent airport being controlled by DR2/3; heading 130 and climbing to 5;000 FT. DR 2/3 is suppose to stay at 5;000 FT and only climb when clear of DR1's traffic. The procedure is in place to separate DR1 traffic from DR2/3 traffic works today. The DR2/3 Controller just needs to observe DR1's traffic before climbing out of 5;000 FT.

Data retrieved from NASA's ASRS site as of July 2013 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.