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

Attributes
ACN	191837
Time
Date	199110
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : ldn
State Reference	VA
Altitude	msl bound lower : 21000 msl bound upper : 21800
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : direct enroute airway : zdc
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 Other
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 22
ASRS Report	191837
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	atc equipment other atc equipment : unspecified
Resolutory Action	none taken : detected after the fact
Consequence	faa : investigated
Miss Distance	horizontal : 27000 vertical : 800
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X climbing out of dca-ldn J134 stl climbing to FL270. Air carrier Y climbing out of dca-ldn J134 ind climbing to FL210. Aircraft approximately 6-7 mi apart. I assigned air carrier X 280 KTS or greater. He was out of FL210. Air carrier Y given 250 KTS and climbed to FL210 which air carrier X was out of. Air carrier X climbed very slowly and I didn't realize it. Air carrier Y climbed very quickly -- he climbed 4000 ft while the air carrier X climbed 400-500 ft. This situation caused a loss of separation. I should have realized that air carrier Y would bleed off airspeed by climbing steeper. I had several other aircraft on frequency and when I saw conflict alert go off, there was just 5 mi and 800 ft separation with air carrier Y leveling at FL210.

Original NASA ASRS Text

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

Narrative: ACR X CLBING OUT OF DCA-LDN J134 STL CLBING TO FL270. ACR Y CLBING OUT OF DCA-LDN J134 IND CLBING TO FL210. ACFT APPROX 6-7 MI APART. I ASSIGNED ACR X 280 KTS OR GREATER. HE WAS OUT OF FL210. ACR Y GIVEN 250 KTS AND CLBED TO FL210 WHICH ACR X WAS OUT OF. ACR X CLBED VERY SLOWLY AND I DIDN'T REALIZE IT. ACR Y CLBED VERY QUICKLY -- HE CLBED 4000 FT WHILE THE ACR X CLBED 400-500 FT. THIS SITUATION CAUSED A LOSS OF SEPARATION. I SHOULD HAVE REALIZED THAT ACR Y WOULD BLEED OFF AIRSPD BY CLBING STEEPER. I HAD SEVERAL OTHER ACFT ON FREQ AND WHEN I SAW CONFLICT ALERT GO OFF, THERE WAS JUST 5 MI AND 800 FT SEPARATION WITH ACR Y LEVELING AT FL210.

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.