Narrative:

This incident occurred on the fifth day of a five day work week and within 20 mins of being relieved of duty. Backgnd. Inbnds landing midway airport from the left are required to be at FL290 before entering the next sectors airspace (approximately 90 mi west of the bradford VOR). The sectors involved in the incident include iowa city, FL240, FL310, and washington sector, FL330, FL999. During the majority of the day these two sectors which lie on top of each other were combined into one sector, which I worked. When the incident occurred, these two sectors were separated. Incident. Cpr X an mdt was inbound to midway airport from the west at FL370 and on my frequency at the washington sector. My normal action for this aircraft would be to descend to FL330 and handoff to the iowa city sector. The iowa city sector would then descend the aircraft to FL290 and handoff to the bradford sector. When reported on my frequency, I called the bradford sector for approval to enter the airspace at FL330 instead of FL290. (This is common practice for aircraft such as mdt, cpr, jets). The bradford sector approved entering their airspace at FL330. I wrote 330/ok and circled it on my strip to indicate that the bradford sector had approved the altitude. I then issued descent to cpr X to 'descend and maintain FL330'. The pilot replied by asking if he could descend at pilot's discretion due to buildups in the area. I did a range-blaring to get a good crossing restriction for the aircraft and issued to the pilot 'cross 90 mi west of bradford at and maintain FL290'. As I issued the clearance I wrote on the strip X90 west at FL330, thinking I had issued FL330. The aircraft was handed off and changed frequency while in descent and eventually descended through a wbound air carrier Y, medium large transport at FL310.

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Original NASA ASRS Text

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

Narrative: THIS INCIDENT OCCURRED ON THE FIFTH DAY OF A FIVE DAY WORK WK AND WITHIN 20 MINS OF BEING RELIEVED OF DUTY. BACKGND. INBNDS LNDG MIDWAY ARPT FROM THE L ARE REQUIRED TO BE AT FL290 BEFORE ENTERING THE NEXT SECTORS AIRSPACE (APPROX 90 MI W OF THE BRADFORD VOR). THE SECTORS INVOLVED IN THE INCIDENT INCLUDE IOWA CITY, FL240, FL310, AND WASHINGTON SECTOR, FL330, FL999. DURING THE MAJORITY OF THE DAY THESE TWO SECTORS WHICH LIE ON TOP OF EACH OTHER WERE COMBINED INTO ONE SECTOR, WHICH I WORKED. WHEN THE INCIDENT OCCURRED, THESE TWO SECTORS WERE SEPARATED. INCIDENT. CPR X AN MDT WAS INBND TO MIDWAY ARPT FROM THE W AT FL370 AND ON MY FREQ AT THE WASHINGTON SECTOR. MY NORMAL ACTION FOR THIS ACFT WOULD BE TO DSND TO FL330 AND HDOF TO THE IOWA CITY SECTOR. THE IOWA CITY SECTOR WOULD THEN DSND THE ACFT TO FL290 AND HDOF TO THE BRADFORD SECTOR. WHEN RPTED ON MY FREQ, I CALLED THE BRADFORD SECTOR FOR APPROVAL TO ENTER THE AIRSPACE AT FL330 INSTEAD OF FL290. (THIS IS COMMON PRACTICE FOR ACFT SUCH AS MDT, CPR, JETS). THE BRADFORD SECTOR APPROVED ENTERING THEIR AIRSPACE AT FL330. I WROTE 330/OK AND CIRCLED IT ON MY STRIP TO INDICATE THAT THE BRADFORD SECTOR HAD APPROVED THE ALT. I THEN ISSUED DSCNT TO CPR X TO 'DSND AND MAINTAIN FL330'. THE PLT REPLIED BY ASKING IF HE COULD DSND AT PLT'S DISCRETION DUE TO BUILDUPS IN THE AREA. I DID A RANGE-BLARING TO GET A GOOD XING RESTRICTION FOR THE ACFT AND ISSUED TO THE PLT 'CROSS 90 MI W OF BRADFORD AT AND MAINTAIN FL290'. AS I ISSUED THE CLRNC I WROTE ON THE STRIP X90 W AT FL330, THINKING I HAD ISSUED FL330. THE ACFT WAS HANDED OFF AND CHANGED FREQ WHILE IN DSCNT AND EVENTUALLY DSNDED THROUGH A WBOUND ACR Y, MLG AT FL310.

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.