Narrative:

This has been a recurring event and has the potential to create a confusing or unsafe situation. We were in cruise on a victor airway while talking to ZLA. Center told us to 'turn right heading 315 degrees.' I read back the heading and asked for a purpose for the vector. ATC did not reply. I repeated the question. ATC simply repeated the instruction to fly heading 315 degrees and again did not give a reason. The captain overheard the exchange and also asked ATC the purpose of the vector. He explained that we needed to know for lost communication purposes. ATC finally responded curtly with 'traffic.' several mins later; ATC questioned our intent if no reason for the vector had been given. We responded that we would not have made the turn because the clearance would have been incomplete and confusing in the event of lost communication. No further exchanges were made regarding the matter. This form of pilot intimidation is potentially hazardous should an actual lost communication situation occur. As pilots; we need to know what to do if the radios fail; and it is ATC's job to include the purpose of the vector when vectors are initiated. At the very least; ATC absolutely needs to respond when asked about the reason for a vector. In our case; ATC did not give a reason until being asked 3 times.

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Original NASA ASRS Text

Title: EMB120 PLT RECEIVES VECTORS OFF AIRWAY WITH NO STATED REASON FROM ZLA.

Narrative: THIS HAS BEEN A RECURRING EVENT AND HAS THE POTENTIAL TO CREATE A CONFUSING OR UNSAFE SITUATION. WE WERE IN CRUISE ON A VICTOR AIRWAY WHILE TALKING TO ZLA. CTR TOLD US TO 'TURN R HDG 315 DEGS.' I READ BACK THE HDG AND ASKED FOR A PURPOSE FOR THE VECTOR. ATC DID NOT REPLY. I REPEATED THE QUESTION. ATC SIMPLY REPEATED THE INSTRUCTION TO FLY HDG 315 DEGS AND AGAIN DID NOT GIVE A REASON. THE CAPT OVERHEARD THE EXCHANGE AND ALSO ASKED ATC THE PURPOSE OF THE VECTOR. HE EXPLAINED THAT WE NEEDED TO KNOW FOR LOST COM PURPOSES. ATC FINALLY RESPONDED CURTLY WITH 'TFC.' SEVERAL MINS LATER; ATC QUESTIONED OUR INTENT IF NO REASON FOR THE VECTOR HAD BEEN GIVEN. WE RESPONDED THAT WE WOULD NOT HAVE MADE THE TURN BECAUSE THE CLRNC WOULD HAVE BEEN INCOMPLETE AND CONFUSING IN THE EVENT OF LOST COM. NO FURTHER EXCHANGES WERE MADE REGARDING THE MATTER. THIS FORM OF PLT INTIMIDATION IS POTENTIALLY HAZARDOUS SHOULD AN ACTUAL LOST COM SITUATION OCCUR. AS PLTS; WE NEED TO KNOW WHAT TO DO IF THE RADIOS FAIL; AND IT IS ATC'S JOB TO INCLUDE THE PURPOSE OF THE VECTOR WHEN VECTORS ARE INITIATED. AT THE VERY LEAST; ATC ABSOLUTELY NEEDS TO RESPOND WHEN ASKED ABOUT THE REASON FOR A VECTOR. IN OUR CASE; ATC DID NOT GIVE A REASON UNTIL BEING ASKED 3 TIMES.

Data retrieved from NASA's ASRS site as of January 2009 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.