ZJX controller issues visual separation descend clearance to which both aircraft instead respond to ...

Attributes
ACN	520623
Time
Date	200108
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : zjx.artcc
State Reference	FL
Altitude	msl single value : 16000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zjx.artcc
Operator	common carrier : air carrier
Make Model Name	Challenger CL600
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zjx.artcc
Operator	common carrier : air carrier
Make Model Name	Brasilia EMB-120 All Series
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller military : 4 controller radar : 19
ASRS Report	520623
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne critical non adherence : clearance
Independent Detector	atc equipment : conflict alert aircraft equipment : tcas other controllera other flight crewa other flight crewb
Resolutory Action	controller : issued advisory controller : issued new clearance controller : separated traffic flight crew : returned to original clearance
Consequence	faa : investigated faa : reviewed incident with flight crew
Miss Distance	horizontal : 11000 vertical : 400
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

The CJ1 (aircraft X) was descending to 17000 ft. The E120 level at 16000 ft. I asked the CJ1 if he had visual with the E120. He replied, 'I see him.' I issued 'maintain visual separation from that traffic, descend and maintain 11000 ft' (unreadable transmission). The CJ1 asked 'was that 11000 ft for us?' I issued 'maintain visual separation from that traffic, descend and maintain 11000 ft' (another unreadable transmission). The CJ1 started descending, conflict alert went off. The CJ1 stated 'we had an RA and we're climbing back up to 17000 ft.' the E120 stated 'we had an RA and descended 400 ft.' the CJ1 asked me about the traffic and I said 'you said you saw the traffic and I issued you a visual separation clearance.' it was then I switched the CJ1 to myr approach.

Original NASA ASRS Text

Title: ZJX CTLR ISSUES VISUAL SEPARATION DSND CLRNC TO WHICH BOTH ACFT INSTEAD RESPOND TO THEIR TCASII ALERTS.

Narrative: THE CJ1 (ACFT X) WAS DSNDING TO 17000 FT. THE E120 LEVEL AT 16000 FT. I ASKED THE CJ1 IF HE HAD VISUAL WITH THE E120. HE REPLIED, 'I SEE HIM.' I ISSUED 'MAINTAIN VISUAL SEPARATION FROM THAT TFC, DSND AND MAINTAIN 11000 FT' (UNREADABLE XMISSION). THE CJ1 ASKED 'WAS THAT 11000 FT FOR US?' I ISSUED 'MAINTAIN VISUAL SEPARATION FROM THAT TFC, DSND AND MAINTAIN 11000 FT' (ANOTHER UNREADABLE XMISSION). THE CJ1 STARTED DSNDING, CONFLICT ALERT WENT OFF. THE CJ1 STATED 'WE HAD AN RA AND WE'RE CLBING BACK UP TO 17000 FT.' THE E120 STATED 'WE HAD AN RA AND DSNDED 400 FT.' THE CJ1 ASKED ME ABOUT THE TFC AND I SAID 'YOU SAID YOU SAW THE TFC AND I ISSUED YOU A VISUAL SEPARATION CLRNC.' IT WAS THEN I SWITCHED THE CJ1 TO MYR APCH.

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.

ZJX controller issues visual separation descend clearance to which both aircraft instead respond to their TCASII alerts.