Air carrier X had less than standard separation from air carrier Y. System error.

Attributes
ACN	178460
Time
Date	199105
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : lit
State Reference	AR
Altitude	msl bound lower : 31000 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zme
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute : direct enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
ASRS Report	178460
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	faa : investigated
Miss Distance	horizontal : 27600 vertical : 1400
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

D side informed me that air carrier X was requesting FL350 (currently at FL310) coming from ZME sector 25. Air carrier X was southwest on J101 northeast of lit. Traffic was wbound approximately 5-10 mi south air carrier X at FL350. 2 other aircraft on J131 were also swbound to houston area (air carrier Y at FL310 the second at FL350). After air carrier X was clear of wbound traffic at FL350, the D side reminded me that he had requested FL350. I then informed air carrier X that I would be unable his request for FL350 due to traffic converging at lit. After that transmission I had accepted handoffs on 2 or more other aircraft and 1 of them realized that air carrier X was also in conflict with air carrier Y coming down J131 so I climbed air carrier X to FL330 at XX33Z. In the next few mins several aircraft began checking on frequency and some frequency congestion occurred. (This was due to using 2 separate UHF and VHF at same time.) after approximately 2 mins I realized that air carrier X was not climbing as well as anticipated so I attempted to turn the aircraft 30 degree to the right. After issuing the clearance all I heard was part of a transmission request to deviate to the east. I then issued a clearance for air carrier Y to turn 30 degree to the left. Result: no response from air carrier Y. I issued clearance again, and this time got a response. Now I go back and reissue the clearance for air carrier X to turn 30 degree right my clearance is acknowledged, but the turns did not take effect quick enough and at approximately XX36Z separation was lost between air carrier X and air carrier Y. I believe that air carrier X did not climb as fast as he should have, because at XX37Z he reported leveling at FL330. I believe that he should have advised the controller if the climb rate was going to be less than 750 FPM. Also, by only using 1 VHF and UHF could have avoided the frequency congestion and allowed the aircraft to acknowledge the turns quicker and thus avoided the incident. (4.6 mi and 1400 ft.)

Original NASA ASRS Text

Title: ACR X HAD LTSS FROM ACR Y. SYS ERROR.

Narrative: D SIDE INFORMED ME THAT ACR X WAS REQUESTING FL350 (CURRENTLY AT FL310) COMING FROM ZME SECTOR 25. ACR X WAS SW ON J101 NE OF LIT. TFC WAS WBOUND APPROX 5-10 MI S ACR X AT FL350. 2 OTHER ACFT ON J131 WERE ALSO SWBOUND TO HOUSTON AREA (ACR Y AT FL310 THE SECOND AT FL350). AFTER ACR X WAS CLEAR OF WBOUND TFC AT FL350, THE D SIDE REMINDED ME THAT HE HAD REQUESTED FL350. I THEN INFORMED ACR X THAT I WOULD BE UNABLE HIS REQUEST FOR FL350 DUE TO TFC CONVERGING AT LIT. AFTER THAT XMISSION I HAD ACCEPTED HDOFS ON 2 OR MORE OTHER ACFT AND 1 OF THEM REALIZED THAT ACR X WAS ALSO IN CONFLICT WITH ACR Y COMING DOWN J131 SO I CLBED ACR X TO FL330 AT XX33Z. IN THE NEXT FEW MINS SEVERAL ACFT BEGAN CHKING ON FREQ AND SOME FREQ CONGESTION OCCURRED. (THIS WAS DUE TO USING 2 SEPARATE UHF AND VHF AT SAME TIME.) AFTER APPROX 2 MINS I REALIZED THAT ACR X WAS NOT CLBING AS WELL AS ANTICIPATED SO I ATTEMPTED TO TURN THE ACFT 30 DEG TO THE R. AFTER ISSUING THE CLRNC ALL I HEARD WAS PART OF A XMISSION REQUEST TO DEVIATE TO THE E. I THEN ISSUED A CLRNC FOR ACR Y TO TURN 30 DEG TO THE L. RESULT: NO RESPONSE FROM ACR Y. I ISSUED CLRNC AGAIN, AND THIS TIME GOT A RESPONSE. NOW I GO BACK AND REISSUE THE CLRNC FOR ACR X TO TURN 30 DEG R MY CLRNC IS ACKNOWLEDGED, BUT THE TURNS DID NOT TAKE EFFECT QUICK ENOUGH AND AT APPROX XX36Z SEPARATION WAS LOST BTWN ACR X AND ACR Y. I BELIEVE THAT ACR X DID NOT CLB AS FAST AS HE SHOULD HAVE, BECAUSE AT XX37Z HE RPTED LEVELING AT FL330. I BELIEVE THAT HE SHOULD HAVE ADVISED THE CTLR IF THE CLB RATE WAS GOING TO BE LESS THAN 750 FPM. ALSO, BY ONLY USING 1 VHF AND UHF COULD HAVE AVOIDED THE FREQ CONGESTION AND ALLOWED THE ACFT TO ACKNOWLEDGE THE TURNS QUICKER AND THUS AVOIDED THE INCIDENT. (4.6 MI AND 1400 FT.)

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.