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

Attributes
ACN	176530
Time
Date	199104
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : ard
State Reference	PA
Altitude	msl bound lower : 11000 msl bound upper : 12000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc
Operator	common carrier : air carrier
Make Model Name	Medium Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
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 : 9
ASRS Report	176530
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation non adherence : published procedure
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Miss Distance	vertical : 700
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I was working sector 19 and 18 combined, we were extremely busy with WX between ZDC and N90. Numerous aircraft were deviating with many other aircraft on headings for spacing. I had been on position about 1 hour. The TRACON was requiring 20 mi at 250 KTS on lga arrs. We went to a single flow for lga/ewr due to deviations and WX, therefore it was imperative that sector 18 and 19 be recombined. Air carrier X checked on frequency and I issued air carrier Y at 110. I issued numerous other control instructions and I turned all lga inbnds to headings for spacing. I issued air carrier X heading and 120 altitude. When I reclred air carrier X direct ard and restated the altitude to maintain I said 110. I thought I said 120. No one including myself caught the readback. I observed air carrier X 119 and said air carrier X verify at 120. He said negative, descending to 110. I climbed him to 120 and immediately descended air carrier Y to 80 with an expeditious descent. No evasive action was taken.

Original NASA ASRS Text

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

Narrative: I WAS WORKING SECTOR 19 AND 18 COMBINED, WE WERE EXTREMELY BUSY WITH WX BTWN ZDC AND N90. NUMEROUS ACFT WERE DEVIATING WITH MANY OTHER ACFT ON HDGS FOR SPACING. I HAD BEEN ON POS ABOUT 1 HR. THE TRACON WAS REQUIRING 20 MI AT 250 KTS ON LGA ARRS. WE WENT TO A SINGLE FLOW FOR LGA/EWR DUE TO DEVS AND WX, THEREFORE IT WAS IMPERATIVE THAT SECTOR 18 AND 19 BE RECOMBINED. ACR X CHKED ON FREQ AND I ISSUED ACR Y AT 110. I ISSUED NUMEROUS OTHER CTL INSTRUCTIONS AND I TURNED ALL LGA INBNDS TO HDGS FOR SPACING. I ISSUED ACR X HDG AND 120 ALT. WHEN I RECLRED ACR X DIRECT ARD AND RESTATED THE ALT TO MAINTAIN I SAID 110. I THOUGHT I SAID 120. NO ONE INCLUDING MYSELF CAUGHT THE READBACK. I OBSERVED ACR X 119 AND SAID ACR X VERIFY AT 120. HE SAID NEGATIVE, DSNDING TO 110. I CLBED HIM TO 120 AND IMMEDIATELY DSNDED ACR Y TO 80 WITH AN EXPEDITIOUS DSNT. NO EVASIVE ACTION WAS TAKEN.

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.