EMB120 makes heading deviation due to poor controller phraseology.

Attributes
ACN	321020
Time
Date	199511
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : gso
State Reference	NC
Altitude	msl bound lower : 10000 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl
Operator	common carrier : air carrier
Make Model Name	Brasilia EMB-120 All Series
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	arrival other enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 270 flight time total : 8000 flight time type : 4500
ASRS Report	321020
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	other anomaly other other spatial deviation
Independent Detector	other controllera
Resolutory Action	flight crew : returned to intended course or assigned course none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation other

Narrative:

We were en route to greensboro, nc, flying the brook 2 arrival approaching the brook intersection from the spa VOR. 4 mi south of brook we received the clearance -- do not intercept the 282 degree radial inbound to gso. Since I was busy obtaining ATIS at the time I did not hear my first officer read back what he thought he heard -- intercept the 282 degree radial inbound to gso. Upon reaching brook he made the normal turn inbound to the gso VOR. I did not detect the miscom until after he had made the turn and we received a call from center directing us to turn back northbound for traffic. We executed an immediate left turn to our previous course. 2 factors contributed to this incident. First, due to my workload at the time I did not catch the error even though I had overheard the proper clearance. Secondly, a clearance such as this is not normally issued as do not, followed by the normal routing. Instead, we would normally hear -- continue present heading, do not intercept and arrival. The former clearance is much easier to misunderstand than the latter.

Original NASA ASRS Text

Title: EMB120 MAKES HEADING DEV DUE TO POOR CTLR PHRASEOLOGY.

Narrative: WE WERE ENRTE TO GREENSBORO, NC, FLYING THE BROOK 2 ARR APCHING THE BROOK INTXN FROM THE SPA VOR. 4 MI S OF BROOK WE RECEIVED THE CLRNC -- DO NOT INTERCEPT THE 282 DEG RADIAL INBOUND TO GSO. SINCE I WAS BUSY OBTAINING ATIS AT THE TIME I DID NOT HEAR MY FO READ BACK WHAT HE THOUGHT HE HEARD -- INTERCEPT THE 282 DEG RADIAL INBOUND TO GSO. UPON REACHING BROOK HE MADE THE NORMAL TURN INBOUND TO THE GSO VOR. I DID NOT DETECT THE MISCOM UNTIL AFTER HE HAD MADE THE TURN AND WE RECEIVED A CALL FROM CTR DIRECTING US TO TURN BACK NBOUND FOR TFC. WE EXECUTED AN IMMEDIATE L TURN TO OUR PREVIOUS COURSE. 2 FACTORS CONTRIBUTED TO THIS INCIDENT. FIRST, DUE TO MY WORKLOAD AT THE TIME I DID NOT CATCH THE ERROR EVEN THOUGH I HAD OVERHEARD THE PROPER CLRNC. SECONDLY, A CLRNC SUCH AS THIS IS NOT NORMALLY ISSUED AS DO NOT, FOLLOWED BY THE NORMAL ROUTING. INSTEAD, WE WOULD NORMALLY HEAR -- CONTINUE PRESENT HEADING, DO NOT INTERCEPT AND ARR. THE FORMER CLRNC IS MUCH EASIER TO MISUNDERSTAND THAN THE LATTER.

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.