Narrative:

I was working R35. Wilmington high sector at ZDC; 17 aircraft on frequency. I descended X from FL350 to FL330 -- a phl arrival. FL330 is a requirement for phl and phl satellite (FL320 or below) in this sector. Traffic sbound was Y at FL340 -- a jax arrival. Traffic was nose-to-nose; but there was plenty of room to descend the phl arrival. I couldn't immediately turn either aircraft comfortably due to adjacent traffic at FL350 and FL340. There was a moderate amount of complexity in the sector due to in-trail flow requirements for phl; bos; and mco. There were 5 phl arrs in my traffic mix -- 2 of which were on vectors for spacing. There were 2 bos arrs both on vectors to achieve spacing. There were two myr arrs on vectors from descent through traffic; both entered the sector at FL340 and needed to descend to FL240. X was issued the descent clearance -- the readback was partially blocked by another aircraft. By the time I was able to re-issue the descent clearance to X; 21 seconds had elapsed. I turned the sbound Y to a 180 degree heading. I also turned X to the left. I turned Y further to a 160 degree heading. The 21 seconds made a difference. I should have reissued the descent clearance immediately instead of talking to the other aircraft; a frequency clarification. We are short staffed and spend long periods of time on busy sectors.

Related reports:

Google
 

Original NASA ASRS Text

Title: ZDC CTLR EXPERIENCED OPERROR AT FL340 WHEN DESCENDING OPPOSITE DIR TFC THROUGH OCCUPIED ALT; CORRECTIVE ACTION TOO LITTLE TOO LATE.

Narrative: I WAS WORKING R35. WILMINGTON HIGH SECTOR AT ZDC; 17 ACFT ON FREQ. I DSNDED X FROM FL350 TO FL330 -- A PHL ARR. FL330 IS A REQUIREMENT FOR PHL AND PHL SATELLITE (FL320 OR BELOW) IN THIS SECTOR. TFC SBOUND WAS Y AT FL340 -- A JAX ARR. TFC WAS NOSE-TO-NOSE; BUT THERE WAS PLENTY OF ROOM TO DSND THE PHL ARR. I COULDN'T IMMEDIATELY TURN EITHER ACFT COMFORTABLY DUE TO ADJACENT TFC AT FL350 AND FL340. THERE WAS A MODERATE AMOUNT OF COMPLEXITY IN THE SECTOR DUE TO IN-TRAIL FLOW REQUIREMENTS FOR PHL; BOS; AND MCO. THERE WERE 5 PHL ARRS IN MY TFC MIX -- 2 OF WHICH WERE ON VECTORS FOR SPACING. THERE WERE 2 BOS ARRS BOTH ON VECTORS TO ACHIEVE SPACING. THERE WERE TWO MYR ARRS ON VECTORS FROM DSCNT THROUGH TFC; BOTH ENTERED THE SECTOR AT FL340 AND NEEDED TO DSND TO FL240. X WAS ISSUED THE DSCNT CLRNC -- THE READBACK WAS PARTIALLY BLOCKED BY ANOTHER ACFT. BY THE TIME I WAS ABLE TO RE-ISSUE THE DSCNT CLRNC TO X; 21 SECONDS HAD ELAPSED. I TURNED THE SBOUND Y TO A 180 DEG HDG. I ALSO TURNED X TO THE L. I TURNED Y FURTHER TO A 160 DEG HDG. THE 21 SECONDS MADE A DIFFERENCE. I SHOULD HAVE REISSUED THE DSCNT CLRNC IMMEDIATELY INSTEAD OF TALKING TO THE OTHER ACFT; A FREQ CLARIFICATION. WE ARE SHORT STAFFED AND SPEND LONG PERIODS OF TIME ON BUSY SECTORS.

Data retrieved from NASA's ASRS site as of January 2009 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.