MD88 crew was descended through an occupied altitude by ZDC ARTCC radar controller.

Attributes
ACN	515589
Time
Date	200106
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : dca.airport
State Reference	DC
Altitude	msl bound lower : 21650 msl bound upper : 22000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc.artcc tracon : i90.tracon
Operator	common carrier : air carrier
Make Model Name	MD-88
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : approach
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zdc.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	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 8474 flight time type : 3710
ASRS Report	515589
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	conflict : airborne critical non adherence : published procedure non adherence : required legal separation
Independent Detector	aircraft equipment : tcas other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : took evasive action flight crew : returned to original clearance flight crew : took precautionary avoidance action
Miss Distance	horizontal : 6000 vertical : 700
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

We were in the initial descent to dca, level at FL220. ATC instructed us to descend to FL190. The first officer began the descent. At that point, I noticed some traffic that might have been conflict. I asked the first officer to stop his descent and pointed out the traffic to ATC. He said to immediately return to FL220 and said he missed the traffic. I believe the first officer descended no more than 350 ft from FL220. As he was correcting to FL220, the TCASII gave us an RA to climb. Returning to FL220 silenced the TCASII. The controller thanked us several times for pointing out the traffic.

Original NASA ASRS Text

Title: MD88 CREW WAS DSNDED THROUGH AN OCCUPIED ALT BY ZDC ARTCC RADAR CTLR.

Narrative: WE WERE IN THE INITIAL DSCNT TO DCA, LEVEL AT FL220. ATC INSTRUCTED US TO DSND TO FL190. THE FO BEGAN THE DSCNT. AT THAT POINT, I NOTICED SOME TFC THAT MIGHT HAVE BEEN CONFLICT. I ASKED THE FO TO STOP HIS DSCNT AND POINTED OUT THE TFC TO ATC. HE SAID TO IMMEDIATELY RETURN TO FL220 AND SAID HE MISSED THE TFC. I BELIEVE THE FO DSNDED NO MORE THAN 350 FT FROM FL220. AS HE WAS CORRECTING TO FL220, THE TCASII GAVE US AN RA TO CLB. RETURNING TO FL220 SILENCED THE TCASII. THE CTLR THANKED US SEVERAL TIMES FOR POINTING OUT THE TFC.

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.