Misinterp of a clearance leads to an near midair collision.

Attributes
ACN	492236
Time
Date	200011
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : roa.airport
State Reference	VA
Altitude	msl single value : 38
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : roa.tracon
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Retractable Gear
Operating Under FAR Part	Part 91
Route In Use	approach : instrument precision arrival : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : roa.tracon
Make Model Name	Sundowner 23
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : cfi pilot : instrument
Experience	flight time last 90 days : 182 flight time total : 1782 flight time type : 1782
ASRS Report	492236
Person 2
Qualification	pilot : private
Events
Anomaly	conflict : nmac non adherence : published procedure non adherence : required legal separation
Resolutory Action	none taken : anomaly accepted none taken : detected after the fact
Miss Distance	horizontal : 0 vertical : 100
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance Aircraft
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

On IFR approach to roa in night VMC, with the field in sight, given vectors for sequence. Assigned heading 250 degrees and 3800 ft MSL, traffic (a commuter) called at our 12 O'clock position and reported in sight. Then assigned 240 degree heading, 3800 ft MSL with additional traffic at 9 O'clock position. I read back '240 degree heading, 3800 ft looking for traffic.' ATC shortly later asked me to 'say heading,' I replied '240 degree heading as assigned.' ATC advised they had assigned 140 degrees, so I turned to 140 degrees, advised that I had 'heard and read back 240 degrees' and advised 'sorry.' at this point I passed over traffic (a BEC23) about 100 ft below. Subsequently landed without incident. On the ground after landing the BEC23 pilot spoke with me and stated that he, too, had heard ATC assign 240 degrees to us and our read back of 240 degrees. He stated that we passed over him (he had us in sight) by 50 ft.

Original NASA ASRS Text

Title: MISINTERP OF A CLRNC LEADS TO AN NMAC.

Narrative: ON IFR APCH TO ROA IN NIGHT VMC, WITH THE FIELD IN SIGHT, GIVEN VECTORS FOR SEQUENCE. ASSIGNED HEADING 250 DEGS AND 3800 FT MSL, TFC (A COMMUTER) CALLED AT OUR 12 O'CLOCK POS AND RPTED IN SIGHT. THEN ASSIGNED 240 DEG HDG, 3800 FT MSL WITH ADDITIONAL TFC AT 9 O'CLOCK POS. I READ BACK '240 DEG HDG, 3800 FT LOOKING FOR TFC.' ATC SHORTLY LATER ASKED ME TO 'SAY HEADING,' I REPLIED '240 DEG HDG AS ASSIGNED.' ATC ADVISED THEY HAD ASSIGNED 140 DEGS, SO I TURNED TO 140 DEGS, ADVISED THAT I HAD 'HEARD AND READ BACK 240 DEGS' AND ADVISED 'SORRY.' AT THIS POINT I PASSED OVER TFC (A BEC23) ABOUT 100 FT BELOW. SUBSEQUENTLY LANDED WITHOUT INCIDENT. ON THE GND AFTER LNDG THE BEC23 PLT SPOKE WITH ME AND STATED THAT HE, TOO, HAD HEARD ATC ASSIGN 240 DEGS TO US AND OUR READ BACK OF 240 DEGS. HE STATED THAT WE PASSED OVER HIM (HE HAD US IN SIGHT) BY 50 FT.

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.