Narrative:

We are a citation 650; filed IFR from sua to ZZZ; received clearance prior to taxi. Cleared as filed; maintain 3000 ft; given a squawk and departure frequency. At XA30 and a clear day; we were cleared by tower for takeoff from runway 12. I thought it was strange we were not given a heading for after departure and even queried the other pilot. He was the one who had received the clearance; he said 'yup; as filed.' so on the takeoff roll I asked if he was gonna make a left or right turn to pick up our course for 'as filed.' he said a left turn and we departed runway 12 climbing to 3000 ft. Passing through 2500 ft; I heard tower say 'cessna XXX; squawk 1200.' I assumed he was talking to the wrong plane and said 'cessna XXX is IFR to chicago.' tower came back and said 'I know that; descend and maintain 1500 ft and circle the field overhead.' none of this is computing for us; it was very confusing and we kept thinking he meant the calls for someone else; finally deciding to follow his directions we left 3000 ft for 1500 ft. As we descended; there was an aircraft climbing up below us. We received an RA and began to climb to avoid the traffic climbing below us. The other aircraft was right under us and not in our sight. If we had not had TCAS that day; we quite likely would have descended down into him; on tower's directions. A few seconds later; tower tells us to maintain 3000 ft and call departure. Once we were underway; I called back on tower frequency and asked what that was all about. The controller said he thought we were VFR when he cleared us for takeoff and was rushing to keep us out of center's airspace as he corrected his error. I phoned the tower supervisor the next day and told him that we were descended into another aircraft by a controller. He said because they are 40 mi from the radar site; they sometimes don't pick up all the traffic on their screen. He apologized profusely. I did mention that if it weren't for TCAS we quite likely would have had a midair. He said 'good thing you all have TCAS now.' I should have queried tower about a heading on our takeoff clearance which might have indicated to him we needed a release. And; of course; he should not have cleared us for takeoff without one.

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Original NASA ASRS Text

Title: C560 FLT CREW RECEIVES TCAS RA DURING INITIAL CLIMB DUE TO ATC CONFUSION REGARDING THEIR IFR/VFR STATUS.

Narrative: WE ARE A CITATION 650; FILED IFR FROM SUA TO ZZZ; RECEIVED CLRNC PRIOR TO TAXI. CLRED AS FILED; MAINTAIN 3000 FT; GIVEN A SQUAWK AND DEP FREQ. AT XA30 AND A CLR DAY; WE WERE CLRED BY TWR FOR TKOF FROM RWY 12. I THOUGHT IT WAS STRANGE WE WERE NOT GIVEN A HDG FOR AFTER DEP AND EVEN QUERIED THE OTHER PLT. HE WAS THE ONE WHO HAD RECEIVED THE CLRNC; HE SAID 'YUP; AS FILED.' SO ON THE TKOF ROLL I ASKED IF HE WAS GONNA MAKE A L OR R TURN TO PICK UP OUR COURSE FOR 'AS FILED.' HE SAID A L TURN AND WE DEPARTED RWY 12 CLBING TO 3000 FT. PASSING THROUGH 2500 FT; I HEARD TWR SAY 'CESSNA XXX; SQUAWK 1200.' I ASSUMED HE WAS TALKING TO THE WRONG PLANE AND SAID 'CESSNA XXX IS IFR TO CHICAGO.' TWR CAME BACK AND SAID 'I KNOW THAT; DSND AND MAINTAIN 1500 FT AND CIRCLE THE FIELD OVERHEAD.' NONE OF THIS IS COMPUTING FOR US; IT WAS VERY CONFUSING AND WE KEPT THINKING HE MEANT THE CALLS FOR SOMEONE ELSE; FINALLY DECIDING TO FOLLOW HIS DIRECTIONS WE LEFT 3000 FT FOR 1500 FT. AS WE DSNDED; THERE WAS AN ACFT CLBING UP BELOW US. WE RECEIVED AN RA AND BEGAN TO CLB TO AVOID THE TFC CLBING BELOW US. THE OTHER ACFT WAS RIGHT UNDER US AND NOT IN OUR SIGHT. IF WE HAD NOT HAD TCAS THAT DAY; WE QUITE LIKELY WOULD HAVE DSNDED DOWN INTO HIM; ON TWR'S DIRECTIONS. A FEW SECONDS LATER; TWR TELLS US TO MAINTAIN 3000 FT AND CALL DEP. ONCE WE WERE UNDERWAY; I CALLED BACK ON TWR FREQ AND ASKED WHAT THAT WAS ALL ABOUT. THE CTLR SAID HE THOUGHT WE WERE VFR WHEN HE CLRED US FOR TKOF AND WAS RUSHING TO KEEP US OUT OF CTR'S AIRSPACE AS HE CORRECTED HIS ERROR. I PHONED THE TWR SUPVR THE NEXT DAY AND TOLD HIM THAT WE WERE DSNDED INTO ANOTHER ACFT BY A CTLR. HE SAID BECAUSE THEY ARE 40 MI FROM THE RADAR SITE; THEY SOMETIMES DON'T PICK UP ALL THE TFC ON THEIR SCREEN. HE APOLOGIZED PROFUSELY. I DID MENTION THAT IF IT WEREN'T FOR TCAS WE QUITE LIKELY WOULD HAVE HAD A MIDAIR. HE SAID 'GOOD THING YOU ALL HAVE TCAS NOW.' I SHOULD HAVE QUERIED TWR ABOUT A HDG ON OUR TKOF CLRNC WHICH MIGHT HAVE INDICATED TO HIM WE NEEDED A RELEASE. AND; OF COURSE; HE SHOULD NOT HAVE CLRED US FOR TKOF WITHOUT ONE.

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.