Deviation from clearance results in a loss of separation and a potential conflict.

Attributes
ACN	157990
Time
Date	199009
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : zdc
State Reference	DC
Altitude	msl bound lower : 7000 msl bound upper : 11000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : lit
Operator	general aviation : personal
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other cruise other descent other
Route In Use	enroute : on vectors enroute airway : zdc
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 54 flight time total : 810 flight time type : 750
ASRS Report	157990
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : clearance non adherence : required legal separation other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation other

Narrative:

I was above the clouds on an IFR flight plan eastbound over hagerstown, md at 11000' with a strong tailwind of approximately 35 KTS. The ZDC controller (134.15) asked me to expedite my descent to 7000'. I was on a heading of 155 degrees. I began my descent and informed the controller 'unable more than 500 FPM descent' (wife with bad cold on board). Center then called back and wanted me at 5000'. I had now entered the clouds and was in moderate turbulence, over mountains, with a strong following wind, heavy rain mixed with wet ice. Center called again and asked me to 'stop descent at 7000 and turn left 10 degrees for traffic.' I complied with the clearance as I understood it to the best of my ability under the conditions. After what seemed about 2 mins I heard nothing from the controller concerning my traffic and, realizing I was in a high density area I decided to query the controller as to my vector to safely pass the traffic. He replied I was now to turn immediately to 340 degrees and that my previous vector was to 10 degrees a few mins ago. Evidently there was a loss of sep because of this misunderstanding. I was in solid IMC at the tie with extremely poor flight conditions stated earlier and never saw the traffic.

Original NASA ASRS Text

Title: DEVIATION FROM CLRNC RESULTS IN A LOSS OF SEPARATION AND A POTENTIAL CONFLICT.

Narrative: I WAS ABOVE THE CLOUDS ON AN IFR FLT PLAN EBND OVER HAGERSTOWN, MD AT 11000' WITH A STRONG TAILWIND OF APPROX 35 KTS. THE ZDC CTLR (134.15) ASKED ME TO EXPEDITE MY DSNT TO 7000'. I WAS ON A HDG OF 155 DEGS. I BEGAN MY DSNT AND INFORMED THE CTLR 'UNABLE MORE THAN 500 FPM DSNT' (WIFE WITH BAD COLD ON BOARD). CENTER THEN CALLED BACK AND WANTED ME AT 5000'. I HAD NOW ENTERED THE CLOUDS AND WAS IN MODERATE TURB, OVER MOUNTAINS, WITH A STRONG FOLLOWING WIND, HVY RAIN MIXED WITH WET ICE. CENTER CALLED AGAIN AND ASKED ME TO 'STOP DSNT AT 7000 AND TURN LEFT 10 DEGS FOR TFC.' I COMPLIED WITH THE CLRNC AS I UNDERSTOOD IT TO THE BEST OF MY ABILITY UNDER THE CONDITIONS. AFTER WHAT SEEMED ABOUT 2 MINS I HEARD NOTHING FROM THE CTLR CONCERNING MY TFC AND, REALIZING I WAS IN A HIGH DENSITY AREA I DECIDED TO QUERY THE CTLR AS TO MY VECTOR TO SAFELY PASS THE TFC. HE REPLIED I WAS NOW TO TURN IMMEDIATELY TO 340 DEGS AND THAT MY PREVIOUS VECTOR WAS TO 10 DEGS A FEW MINS AGO. EVIDENTLY THERE WAS A LOSS OF SEP BECAUSE OF THIS MISUNDERSTANDING. I WAS IN SOLID IMC AT THE TIE WITH EXTREMELY POOR FLT CONDITIONS STATED EARLIER AND NEVER SAW 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.