ZDC controller attempts to resolve pilot overshoot conflict with another IFR en route aircraft.

Attributes
ACN	488561
Time
Date	200010
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : pxt.vortac
State Reference	MD
Altitude	msl bound lower : 10000 msl bound upper : 11000
Environment
Flight Conditions	Marginal
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc.artcc
Operator	general aviation : corporate
Make Model Name	Citationjet, C525/C526
Operating Under FAR Part	Part 91
Flight Phase	cruise : enroute altitude change
Route In Use	enroute : direct enroute : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zdc.artcc
Operator	general aviation : corporate
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 13 controller time certified in position1 : 3
ASRS Report	488561
Person 2
Affiliation	government : faa
Function	controller : handoff position
Qualification	controller : radar
Events
Anomaly	altitude deviation : overshoot conflict : airborne critical inflight encounter : weather non adherence : required legal separation non adherence : published procedure
Independent Detector	atc equipment : conflict alert other controllera other controllerb
Resolutory Action	controller : issued new clearance flight crew : returned to assigned altitude
Consequence	faa : investigated
Miss Distance	vertical : 100
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Aircraft aa checked on my frequency descending to FL190 and landing at esn (easton, md). I advised the pilot there would be an aircraft ab on the frequency also, he acknowledged. The similar sounding call signs did not cause any problems. I assigned aircraft aa a heading of 360 degrees and descended him to 17000 ft. After aircraft aa was clear from sbound traffic at 16000 ft, I cleared him to 11000 ft and advised direct to pxt VOR leaving 15000 ft. The pilot read back the altitude correctly. Aircraft C, at 10000 ft, was swbound over pxt to ric. My d-side said 'what are those two doing by pxt?' the 2 aircraft were 6 mi apart head-on, aircraft C at 10000 ft and aircraft aa's mode C indicated 10300 ft. I climbed aircraft aa to 11000 ft and turned to a heading of 090 degrees and descended aircraft C to 9000 ft. The aircraft never reported seeing each other. Aircraft aa asked 'was I assigned 10000 ft or 11000 ft?' when he started his climb back to 11000 ft. Conflict alert went off after they were 6 mi apart. I am not sure how close the aircraft got to each other.

Original NASA ASRS Text

Title: ZDC CTLR ATTEMPTS TO RESOLVE PLT OVERSHOOT CONFLICT WITH ANOTHER IFR ENRTE ACFT.

Narrative: ACFT AA CHKED ON MY FREQ DSNDING TO FL190 AND LNDG AT ESN (EASTON, MD). I ADVISED THE PLT THERE WOULD BE AN ACFT AB ON THE FREQ ALSO, HE ACKNOWLEDGED. THE SIMILAR SOUNDING CALL SIGNS DID NOT CAUSE ANY PROBS. I ASSIGNED ACFT AA A HDG OF 360 DEGS AND DSNDED HIM TO 17000 FT. AFTER ACFT AA WAS CLR FROM SBOUND TFC AT 16000 FT, I CLRED HIM TO 11000 FT AND ADVISED DIRECT TO PXT VOR LEAVING 15000 FT. THE PLT READ BACK THE ALT CORRECTLY. ACFT C, AT 10000 FT, WAS SWBOUND OVER PXT TO RIC. MY D-SIDE SAID 'WHAT ARE THOSE TWO DOING BY PXT?' THE 2 ACFT WERE 6 MI APART HEAD-ON, ACFT C AT 10000 FT AND ACFT AA'S MODE C INDICATED 10300 FT. I CLBED ACFT AA TO 11000 FT AND TURNED TO A HDG OF 090 DEGS AND DSNDED ACFT C TO 9000 FT. THE ACFT NEVER RPTED SEEING EACH OTHER. ACFT AA ASKED 'WAS I ASSIGNED 10000 FT OR 11000 FT?' WHEN HE STARTED HIS CLB BACK TO 11000 FT. CONFLICT ALERT WENT OFF AFTER THEY WERE 6 MI APART. I AM NOT SURE HOW CLOSE THE ACFT GOT TO EACH OTHER.

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.