Narrative:

Aircraft #2 was issued a restr to cross bambe at 11000 ft. A min later a clearance to descend was issued to aircraft #2. Aircraft #1 was on top of aircraft #2 and assigned FL250 at the time aircraft #2 left FL240. Aircraft #1 was then issued FL190 to start their descent. The conflict alert went off when aircraft #2 was at FL220 and aircraft #1 was at FL236. I issued aircraft #1 FL230 and they read back level at FL230 we are going through. The loss of vertical separation was between FL230 and FL220 but the amic was unsure of the exact altitudes. I was receiving instruction on a sector for cross training purposes due to seventh area implementation at ZFW. I am a developmental and have not had a primary instructor while training on the sector where the error occurred. I was using vertical based on the way I had been instructed the previous session in which I was told to start planes down and watch the situation to make sure it is working. When the planes were issued the descent clrncs there was 2000 ft separation and I felt if both aircraft did profile dscnts separation would be maintained. A second factor was that I had had a cold all week and on the previous day had asked not to train. When I came in on the day of the error, upon signing in, I was told to go to the different specialty to train. Being a developmental and not wanting to look ungrateful for the training opportunity I went to train even though I still felt ill.

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Original NASA ASRS Text

Title: RPTR LOSS OF SEPARATION BTWN AN ACR B737 AND AN ACR MD80 WHEN ALT SEPARATION WAS LOST WHILE BOTH ACFT WERE DSNDING.

Narrative: ACFT #2 WAS ISSUED A RESTR TO CROSS BAMBE AT 11000 FT. A MIN LATER A CLRNC TO DSND WAS ISSUED TO ACFT #2. ACFT #1 WAS ON TOP OF ACFT #2 AND ASSIGNED FL250 AT THE TIME ACFT #2 LEFT FL240. ACFT #1 WAS THEN ISSUED FL190 TO START THEIR DSCNT. THE CONFLICT ALERT WENT OFF WHEN ACFT #2 WAS AT FL220 AND ACFT #1 WAS AT FL236. I ISSUED ACFT #1 FL230 AND THEY READ BACK LEVEL AT FL230 WE ARE GOING THROUGH. THE LOSS OF VERT SEPARATION WAS BTWN FL230 AND FL220 BUT THE AMIC WAS UNSURE OF THE EXACT ALTS. I WAS RECEIVING INSTRUCTION ON A SECTOR FOR CROSS TRAINING PURPOSES DUE TO SEVENTH AREA IMPLEMENTATION AT ZFW. I AM A DEVELOPMENTAL AND HAVE NOT HAD A PRIMARY INSTRUCTOR WHILE TRAINING ON THE SECTOR WHERE THE ERROR OCCURRED. I WAS USING VERT BASED ON THE WAY I HAD BEEN INSTRUCTED THE PREVIOUS SESSION IN WHICH I WAS TOLD TO START PLANES DOWN AND WATCH THE SIT TO MAKE SURE IT IS WORKING. WHEN THE PLANES WERE ISSUED THE DSCNT CLRNCS THERE WAS 2000 FT SEPARATION AND I FELT IF BOTH ACFT DID PROFILE DSCNTS SEPARATION WOULD BE MAINTAINED. A SECOND FACTOR WAS THAT I HAD HAD A COLD ALL WEEK AND ON THE PREVIOUS DAY HAD ASKED NOT TO TRAIN. WHEN I CAME IN ON THE DAY OF THE ERROR, UPON SIGNING IN, I WAS TOLD TO GO TO THE DIFFERENT SPECIALTY TO TRAIN. BEING A DEVELOPMENTAL AND NOT WANTING TO LOOK UNGRATEFUL FOR THE TRAINING OPPORTUNITY I WENT TO TRAIN EVEN THOUGH I STILL FELT ILL.

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.