Mooney pilot given TA, then told no longer a factor but has close proximity with light twin aircraft...

Attributes
ACN	340464
Time
Date	199607
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bwi
State Reference	MD
Altitude	msl bound lower : 2800 msl bound upper : 2800
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bwi
Operator	general aviation : personal
Make Model Name	Mooney Aircraft Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	descent other
Flight Plan	None
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	other : unknown
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 75 flight time total : 2500 flight time type : 1600
ASRS Report	340464
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Events
Anomaly	conflict : nmac
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 1000 vertical : 0

Narrative:

En route from washington national airport to philadelphia international airport, in vicinity of the swann intersection, at 2500 ft, on fringe of the class B airspace, controller reported a slow-moving target ahead at my altitude. There was negative contact, so with ATC concurrence I climbed to 3000 ft. Shortly afterward he reported traffic no factor, so I began a descent back to 2500 ft, advising controller in advance. By this time I had exited the class B airspace but was still within the mode C veil, airspace requiring an altitude-reporting transponder squawk. Going through 2800 ft, at my 1 O'clock, opposite direction, a light twin suddenly appeared. He was in a left turn, possibly as an evasive action to miss me, but I don't know. In any event, we luckily missed. Had I not seen him before it might have been too late. I advised the controller I had just had a close call. He replied that he showed no traffic in my area.

Original NASA ASRS Text

Title: MOONEY PLT GIVEN TA, THEN TOLD NO LONGER A FACTOR BUT HAS CLOSE PROX WITH LIGHT TWIN ACFT.

Narrative: ENRTE FROM WASHINGTON NATIONAL ARPT TO PHILADELPHIA INTL ARPT, IN VICINITY OF THE SWANN INTXN, AT 2500 FT, ON FRINGE OF THE CLASS B AIRSPACE, CTLR RPTED A SLOW-MOVING TARGET AHEAD AT MY ALT. THERE WAS NEGATIVE CONTACT, SO WITH ATC CONCURRENCE I CLBED TO 3000 FT. SHORTLY AFTERWARD HE RPTED TFC NO FACTOR, SO I BEGAN A DSCNT BACK TO 2500 FT, ADVISING CTLR IN ADVANCE. BY THIS TIME I HAD EXITED THE CLASS B AIRSPACE BUT WAS STILL WITHIN THE MODE C VEIL, AIRSPACE REQUIRING AN ALT-RPTING XPONDER SQUAWK. GOING THROUGH 2800 FT, AT MY 1 O'CLOCK, OPPOSITE DIRECTION, A LIGHT TWIN SUDDENLY APPEARED. HE WAS IN A L TURN, POSSIBLY AS AN EVASIVE ACTION TO MISS ME, BUT I DON'T KNOW. IN ANY EVENT, WE LUCKILY MISSED. HAD I NOT SEEN HIM BEFORE IT MIGHT HAVE BEEN TOO LATE. I ADVISED THE CTLR I HAD JUST HAD A CLOSE CALL. HE REPLIED THAT HE SHOWED NO TFC IN MY AREA.

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.