HDG TRACK DEV IN A NON ADHERENCE TO ATC CLRNC INSTRUCTION.

Narrative

NIGHTTIME DEP OUT OF MSP. DEP INSTRUCTIONS WERE TO CLB TO 5000 FT AND MAINTAIN RWY HDG OF 298 DEGS. JUST AFTER LIFTOFF; TWR INSTRUCTED US TO 'MAKE HARD R TURN INSIDE TFC AT 1-2 O'CLOCK TO HDG 360 DEGS.' I WAS KEEPING AN EYE ON OUR TFC WHILE WE MADE OUR TURN WHEN THE CAPT SAID IT WAS NOT A STANDARD DEP AND REQUESTED THE FO TO GET A CLARIFICATION. THE FO SWITCHED TO DEP AND STATED 'WE ARE CLBING TO 5000 FT AND TURNING TO A HDG OF 060 DEGS.' DEP TOLD US TO STOP OUR CLB; WHICH WAS ABOUT 3900 FT AND SAID THERE WAS CONFLICTING TFC AT 5200 FT. WE STOPPED OUR CLB AT 4000 FT; JUST BELOW A CLOUD DECK; MAINTAINING VFR. THE CAPT SAID HE SAW LIGHTS ABOVE THROUGH THE CLOUDS. TCASII NEVER WENT OFF. I THINK THE PROB CAME ABOUT BECAUSE OF THE NONSTANDARD DEP AND THE TWR USED THE WORDS 'HARD TURN' WITH ONLY A RELATIVELY SMALL DEG TURN TO 360 DEGS JUST AFTER LIFTOFF. HOWEVER; THE TERM IS USUALLY ASSOCIATED WITH A GREATER MAGNITUDE OF DEG TURN LIKE 'TO 060 DEGS;' AND THE FACT THE CAPT THOUGHT HE HEARD 060 DEGS. SUPPLEMENTAL INFO FROM ACN 319039: CAPT FLEW THE TKOF FROM MSP RWY 29R; CLRNC WAS RWY HDG TO 5000 FT. AFTER TKOF; THE TWR CTLR ISSUED A 'HARD R TURN TO 360 DEGS IF POSSIBLE;' AS PNF; I READ BACK 'R TURN TO 360 DEGS.' ALL 3 PLTS WERE KEEPING IN SIGHT A PREVIOUS DEP. I BELIEVED THIS WAS THE REASON FOR THE TURN CLRNC. THE CAPT DID NOT RESET HIS HDG BUG FOR THE TURN (IT STILL INDICATED 298 DEGS); AND AS HE TURNED PAST 360 DEGS; I MENTIONED I THOUGHT THE HDG WAS 360 DEGS WE WERE ISSUED. HE THOUGHT IT WAS 060 DEGS; AND WE BOTH THOUGHT THAT MADE MORE SENSE DUE TO THE 'HARD R TURN' INSTRUCTION. (A 60 DEG HDG CHANGE FROM 300 TO 360 DEGS DIDN'T SEEM TO MERIT A HARD TURN.) I FELT UNEASY ABOUT THE CONFUSION AND ADVISED THE DEP CTLR AFTER THE TWR HDOF THAT WE WERE TURNING TO 060 DEGS. HE IMMEDIATELY RESPONDED THAT WE SHOULD BE HDG 360 DEGS; AND CLRED US TO MAINTAIN 4000 FT HDG 360 DEGS DUE TO AN ACFT AT 12 O'CLOCK; 5200 FT; DSNDING TO 5000 FT. THUS WE AVOIDED A SEPARATION CONFLICT; NEVER CLBING ABOVE 4000 FT. NO TCASII ADVISORY OR ALERT RESULTED. IN RETROSPECT; THE PLT CREW FELT IT INAPPROPRIATE FOR THE TWR TO ISSUE A HARD R TURN IN THE TKOF PHASE BECAUSE OF ACFT PERFORMANCE LIMITATIONS. I PURPOSELY DID NOT READ BACK 'HARD R TURN' FOR THAT REASON; BUT SHOULD HAVE DISCUSSED ACCEPTING THIS CLRNC WITH THE CAPT. PERHAPS WE SHOULD HAVE ASKED THE SPECIFIC REASON FOR THE TURN. I DIRECTED MY RECOLLECTION OF THE ASSIGNED HDG AFTER THE CAPT COMMENTED HE HEARD 060 DEGS; AND SHOULD HAVE ASSERTED MYSELF MORE.