ZDC controller described a conflict event when issuing a descent to FL190 thinking the altitude assi...

Attributes
ACN	1124621
Time
Date	201310
Local Time Of Day	1201-1800
Place
Locale Reference	ZDC.ARTCC
State Reference	VA
Aircraft 1
Make Model Name	Global Express (BD700)
Operating Under FAR Part	Part 91
Flight Phase	Descent
Flight Plan	IFR
Aircraft 2
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Person 1
Function	Enroute
Qualification	Air Traffic Control Developmental
Person 2
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	ATC Issue All Types Deviation - Procedural Published Material / Policy

Narrative:

A global express checked on at FL410. At sector 9 we have to descend to hand him off to sector 35 and I saw his traffic at FL380 southbound so I issued a descent to FL390. First transmission; no reply. Again I issued a descent to FL390. After few seconds passed; the express said he missed it and on the third time I issued descent to what I could have sworn was FL390. Upon reviewing tapes I issued FL190 and I missed his read back. Listen carefully for every read back especially when the aircraft missed the first clearance. Issue merging target procedures to aircraft in transition.

Original NASA ASRS Text

Title: ZDC Controller described a conflict event when issuing a descent to FL190 thinking the altitude assignment issued was FL390; the reporter acknowledging s/he missed the read back by the pilot.

Narrative: A Global Express checked on at FL410. At Sector 9 we have to descend to hand him off to Sector 35 and I saw his traffic at FL380 southbound so I issued a descent to FL390. First transmission; no reply. Again I issued a descent to FL390. After few seconds passed; the Express said he missed it and on the third time I issued descent to what I could have sworn was FL390. Upon reviewing tapes I issued FL190 and I missed his read back. Listen carefully for every read back especially when the aircraft missed the first clearance. Issue merging target procedures to aircraft in transition.

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.

ZDC controller described a conflict event when issuing a descent to FL190 thinking the altitude assignment issued was FL390; the reporter acknowledging s/he missed the read back by the pilot.