<< >> NASA ASRS Report 910660, September 2010

ZDC controller described a loss of separation event when descending an aircraft through occupied airspace thinking the aircraft were at reverse altitudes.

Attributes
ACN	910660
Time
Date	201009
Local Time Of Day	0001-0600
Place
Locale Reference	ZDC.ARTCC
State Reference	VA
Aircraft 1
Make Model Name	Regional Jet 200 ER/LR (CRJ200)
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Aircraft 2
Make Model Name	EMB ERJ 170/175 ER&LR
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Flight Plan	IFR
Person 1
Qualification	Air Traffic Control Fully Certified
Person 2
Function	Supervisor / CIC
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Deviation - Procedural Published Material / Policy

Narrative:

An E170 was a rdu inbound at FL210 converging with a CRJ2 at FL220 which was a jqf inbound. Both aircraft needed to be descended. In my mind; I was descending the lower aircraft; but in actuality the CRJ2 was on top and began a descent towards the E170. Both aircraft responded to TCAS resolutions. The CRJ2 informed me of the RA and that he was climbing. The E170 informed me of his RA abd that he was beginning a descent. I issued a clearance to continue the E170's descent to FL190.

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Original NASA ASRS Text

Title: ZDC Controller described a loss of separation event when descending an aircraft through occupied airspace thinking the aircraft were at reverse altitudes.

Narrative: An E170 was a RDU inbound at FL210 converging with a CRJ2 at FL220 which was a JQF inbound. Both aircraft needed to be descended. In my mind; I was descending the lower aircraft; but in actuality the CRJ2 was on top and began a descent towards the E170. Both aircraft responded to TCAS resolutions. The CRJ2 informed me of the RA and that he was climbing. The E170 informed me of his RA abd that he was beginning a descent. I issued a clearance to continue the E170's descent to FL190.

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.