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

Attributes
ACN	123648
Time
Date	198909
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : imp
State Reference	PA
Altitude	msl bound lower : 33000 msl bound upper : 34400
Environment
Flight Conditions	IMC
Light	Dawn
Aircraft 1
Controlling Facilities	artcc : zny
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 3 Turbojet Eng
Navigation In Use	Other
Flight Phase	descent other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 19
ASRS Report	123648
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 other controllera
Resolutory Action	controller : issued new clearance other
Consequence	faa : investigated
Miss Distance	horizontal : 10200 vertical : 1400
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I was involved in a system error between air carrier X, an ewr arrival, and air carrier Y, northbound to pvd. Air carrier X was at FL370 with a crossing clearance to FL180 and would over fly air carrier Y at FL330. I felt air carrier X would stay at altitude until he was clear of air carrier Y that is why the clearance was issued. However air carrier X reported he was starting his descent and I tried to level air carrier X at FL350. He said he may overshoot the altitude. I asked that he not and he informed me that I stopped him too late. Air carrier X was observed leaving FL361 when all the conversation was held. Next sweep showed FL355, next sweep FL344. I feel air carrier X could have stopped his descent in time, however this was nt the case.

Original NASA ASRS Text

Title: ACR X HAD LESS THAN STANDARD SEPARATION FROM ACR Y. SYSTEM ERROR.

Narrative: I WAS INVOLVED IN A SYSTEM ERROR BETWEEN ACR X, AN EWR ARR, AND ACR Y, NBOUND TO PVD. ACR X WAS AT FL370 WITH A XING CLRNC TO FL180 AND WOULD OVER FLY ACR Y AT FL330. I FELT ACR X WOULD STAY AT ALT UNTIL HE WAS CLEAR OF ACR Y THAT IS WHY THE CLRNC WAS ISSUED. HOWEVER ACR X REPORTED HE WAS STARTING HIS DSCNT AND I TRIED TO LEVEL ACR X AT FL350. HE SAID HE MAY OVERSHOOT THE ALT. I ASKED THAT HE NOT AND HE INFORMED ME THAT I STOPPED HIM TOO LATE. ACR X WAS OBSERVED LEAVING FL361 WHEN ALL THE CONVERSATION WAS HELD. NEXT SWEEP SHOWED FL355, NEXT SWEEP FL344. I FEEL ACR X COULD HAVE STOPPED HIS DSCNT IN TIME, HOWEVER THIS WAS NT THE CASE.

Data retrieved from NASA's ASRS site as of August 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.