ZNY controller experienced operational error at FL280 with descending LR25.

Attributes
ACN	613649
Time
Date	200404
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : zny.artcc
State Reference	NY
Altitude	msl single value : 28000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zny.artcc
Operator	general aviation : personal
Make Model Name	Learjet 25
Operating Under FAR Part	Part 91
Flight Phase	cruise : level descent : vacating altitude descent : intermediate altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zny.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
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 radar : 14 controller time certified in position1 : 14 controller time certified in position2 : 3
ASRS Report	613649
Person 2
Affiliation	other
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	atc equipment : conflict alert other controllera
Resolutory Action	controller : issued new clearance
Consequence	faa : investigated
Miss Distance	horizontal : 22800 vertical : 800
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I descended aircraft X, a teb arrival at FL290, to FL250 to get him under air carrier Y at FL270. My attention then went to separate aircraft Z from another teb inbound. I then noticed that aircraft X did not descend at a reasonable rate and I had to stop him at FL280. Aircraft X advised he was 200 ft below the altitude and was climbing back up. If aircraft Y, a lear jet, advised me that his rate of descent was only 400 FPM, this event would not have happened.

Original NASA ASRS Text

Title: ZNY CTLR EXPERIENCED OPERROR AT FL280 WITH DSNDING LR25.

Narrative: I DSNDED ACFT X, A TEB ARR AT FL290, TO FL250 TO GET HIM UNDER ACR Y AT FL270. MY ATTN THEN WENT TO SEPARATE ACFT Z FROM ANOTHER TEB INBOUND. I THEN NOTICED THAT ACFT X DID NOT DSND AT A REASONABLE RATE AND I HAD TO STOP HIM AT FL280. ACFT X ADVISED HE WAS 200 FT BELOW THE ALT AND WAS CLBING BACK UP. IF ACFT Y, A LEAR JET, ADVISED ME THAT HIS RATE OF DSCNT WAS ONLY 400 FPM, THIS EVENT WOULD NOT HAVE HAPPENED.

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.