TRACON controller experienced less than required separation when believing 5000 was issued when in f...

Attributes
ACN	845473
Time
Date	200907
Local Time Of Day	0601-1200
Place
Locale Reference	ALB.Airport
State Reference	NY
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	Climb
Route In Use	Vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Aircraft
Operating Under FAR Part	Part 91
Flight Phase	Descent
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Approach
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Military 5 Air Traffic Control Non Radar 0 Air Traffic Control Radar 6
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict
Miss Distance	Horizontal 2 Vertical 300

Narrative:

No supervisor in TRACON during a moderate to busy period. Less then stellar help from data/flight assist position. Improper strip marking on my part. I thought I assigned the small aircraft 5000 feet when in fact I issued 4000 feet. I should have verified the small aircraft's altitude assignment when I saw the two aircraft were not going to be separated laterally. I was surprised the conflict alert did not activate. My visual scan alerted me to the situation in time to take action; but not in enough time to keep the required IFR separation. I was very busy working aircraft into multiple airports under mostly IMC conditions; my focus was concentrated on the final approach courses; and perhaps I got some 'tunnel vision.'

Original NASA ASRS Text

Title: TRACON Controller experienced less than required separation when believing 5000 was issued when in fact 4000 was assigned; the corrective action taken was too late to maintain separation.

Narrative: No Supervisor in TRACON during a moderate to busy period. Less then stellar help from data/flight assist position. Improper strip marking on my part. I thought I assigned the small aircraft 5000 feet when in fact I issued 4000 feet. I should have verified the small aircraft's altitude assignment when I saw the two aircraft were not going to be separated laterally. I was surprised the conflict alert did not activate. My visual scan alerted me to the situation in time to take action; but not in enough time to keep the required IFR separation. I was very busy working aircraft into multiple airports under mostly IMC conditions; my focus was concentrated on the final approach courses; and perhaps I got some 'tunnel vision.'

Data retrieved from NASA's ASRS site as of April 2012 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.

TRACON controller experienced less than required separation when believing 5000 was issued when in fact 4000 was assigned; the corrective action taken was too late to maintain separation.