A PC12 pilot, departing toa, intercepted a VOR radial after ATC had assigned a heading to maintain.

Attributes
ACN	546389
Time
Date	200204
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : lax.airport
State Reference	CA
Altitude	msl single value : 5000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sct.tracon
Operator	general aviation : corporate
Make Model Name	PC-12
Operating Under FAR Part	Part 91
Flight Phase	climbout : intermediate altitude
Route In Use	departure : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial pilot : cfi pilot : multi engine
Experience	flight time last 90 days : 60 flight time total : 1200 flight time type : 200
ASRS Report	546389
Person 2
Affiliation	government : faa
Function	controller : departure
Events
Anomaly	non adherence : clearance non adherence : published procedure other spatial deviation
Independent Detector	atc equipment other atc equipment : radar other controllera
Resolutory Action	controller : issued alert controller : issued new clearance
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I had checked into socal departure out of 1200 ft. My clearance was a heading to intercept the lax 170 degree radial. However, socal gave me a new heading (250 degrees, I believe) which also was an intercept heading for lax 170 degrees. When ATC gave me a new heading ('turn left to a heading of 250 degrees') I assumed this was a new heading to intercept the lax 170 degree radial, as it was not stated that it was anything else. As such, when the radial came alive, I intercepted it. Once the interception was complete, ATC told me the heading was 250 degrees. I explained I intercepted the lax 170 degree radial since I was never told not to. No loss of separation resulted. I believe ATC has the responsibility to use the format of 'aircraft 12345, turn left heading 250 degrees, vectors seal beach.' if that format was used, I do not believe this would have happened, since I would have been clear this wasn't a vector for the radial, but instead a vector for some other point.

Original NASA ASRS Text

Title: A PC12 PLT, DEPARTING TOA, INTERCEPTED A VOR RADIAL AFTER ATC HAD ASSIGNED A HDG TO MAINTAIN.

Narrative: I HAD CHKED INTO SOCAL DEP OUT OF 1200 FT. MY CLRNC WAS A HDG TO INTERCEPT THE LAX 170 DEG RADIAL. HOWEVER, SOCAL GAVE ME A NEW HDG (250 DEGS, I BELIEVE) WHICH ALSO WAS AN INTERCEPT HDG FOR LAX 170 DEGS. WHEN ATC GAVE ME A NEW HDG ('TURN L TO A HDG OF 250 DEGS') I ASSUMED THIS WAS A NEW HDG TO INTERCEPT THE LAX 170 DEG RADIAL, AS IT WAS NOT STATED THAT IT WAS ANYTHING ELSE. AS SUCH, WHEN THE RADIAL CAME ALIVE, I INTERCEPTED IT. ONCE THE INTERCEPTION WAS COMPLETE, ATC TOLD ME THE HDG WAS 250 DEGS. I EXPLAINED I INTERCEPTED THE LAX 170 DEG RADIAL SINCE I WAS NEVER TOLD NOT TO. NO LOSS OF SEPARATION RESULTED. I BELIEVE ATC HAS THE RESPONSIBILITY TO USE THE FORMAT OF 'ACFT 12345, TURN L HDG 250 DEGS, VECTORS SEAL BEACH.' IF THAT FORMAT WAS USED, I DO NOT BELIEVE THIS WOULD HAVE HAPPENED, SINCE I WOULD HAVE BEEN CLR THIS WASN'T A VECTOR FOR THE RADIAL, BUT INSTEAD A VECTOR FOR SOME OTHER POINT.

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.