ZDC controller transposes intentions and issues descent to wrong air carrier causing conflict.

Attributes
ACN	508999
Time
Date	200104
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : ric.airport
State Reference	VA
Altitude	msl bound lower : 26000 msl bound upper : 27000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zdc.artcc tower : mia.tower
Operator	common carrier : air carrier
Make Model Name	B737-400
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zdc.artcc
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 13 flight time total : 15
ASRS Report	508999
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 170 flight time total : 16000 flight time type : 5000
ASRS Report	508615
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation non adherence : published procedure
Independent Detector	atc equipment : conflict alert other controllera
Resolutory Action	controller : issued new clearance controller : issued advisory controller : separated traffic flight crew : returned to original clearance
Consequence	faa : investigated faa : reviewed incident with flight crew
Miss Distance	horizontal : 21600 vertical : 600
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Similar call signs, marked correct strip, updated correct data block, gave incorrect call sign. I thought I had given descent to bottom aircraft at FL260 and gave it to other above at FL270. Supplemental information from acn 508615: en route from clt to bwi, we were given a descent clearance from FL270 to FL240 from ZDC frequency 127.75. Passing FL260, ZDC asked us if we were level FL240. We said we were passing FL260. ZDC then told us to level at FL260, then told us to climb to FL270. We leveled at FL260 then climbed immediately to FL270. We then noticed an aircraft at FL260 approximately 5 mi ahead of us. We maintained visual contact with aircraft.

Original NASA ASRS Text

Title: ZDC CTLR TRANSPOSES INTENTIONS AND ISSUES DSCNT TO WRONG ACR CAUSING CONFLICT.

Narrative: SIMILAR CALL SIGNS, MARKED CORRECT STRIP, UPDATED CORRECT DATA BLOCK, GAVE INCORRECT CALL SIGN. I THOUGHT I HAD GIVEN DSCNT TO BOTTOM ACFT AT FL260 AND GAVE IT TO OTHER ABOVE AT FL270. SUPPLEMENTAL INFO FROM ACN 508615: ENRTE FROM CLT TO BWI, WE WERE GIVEN A DSCNT CLRNC FROM FL270 TO FL240 FROM ZDC FREQ 127.75. PASSING FL260, ZDC ASKED US IF WE WERE LEVEL FL240. WE SAID WE WERE PASSING FL260. ZDC THEN TOLD US TO LEVEL AT FL260, THEN TOLD US TO CLB TO FL270. WE LEVELED AT FL260 THEN CLBED IMMEDIATELY TO FL270. WE THEN NOTICED AN ACFT AT FL260 APPROX 5 MI AHEAD OF US. WE MAINTAINED VISUAL CONTACT WITH ACFT.

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.