MISCOMMUNICATIONS BETWEEN FLIGHT CREW MEMBERS RESULTED IN UNAUTHORIZED AND UNCOORDINATED IFR DEPARTURE FROM SPS DEVELOPING INTO A TRAFFIC CONFLICT.

Narrative

THIS FLT TOOK OFF FROM SPS WITH A CLOSED TWR AT APPROX XA30. THE WX WAS CLEAR AND 10+ MI VISIBILITY. ON PREFLT; THE FO TOOK OUR CLRNC WITH DEP IN SPS DURING THE WKEND WHEN THE TWR WAS CLOSED. I WAS NOT IN THE ACFT AT THE TIME. THE END OF THE CLRNC FINISHED WITH A 'HOLD FOR RELEASE.' WHEN WE REVIEWED THE CLRNC; THERE WAS NO MENTION BY THE FO OF THE 'HOLD FOR RELEASE' IN THE CLRNC. IT ALSO WAS NOT WRITTEN ON THE PAPER WITH THE CLRNC. THE CLRNC WAS GIVEN APPROX 20-30 MINS PRIOR TO BLOCK-OUT. AFTER THE PREFLT CHKS AND THE PAX BOARDED; WE TAXIED TO RWY 17 FOR DEP. SINCE THE FREQ WAS SCRATCHY WHEN I CANCELED IFR ON THE GND FROM THE INBOUND FLT; I DECIDED I WOULD CLB OUT VFR AND CONTACT DEP AIRBORNE INSTEAD OF ON THE GND. I WAS UNAWARE OF THE 'HOLD FOR RELEASE.' WE COMPLETED ALL TAXI OUT CHKLISTS AND BRIEFS. WE MADE THE NORMAL CTAF RADIO CALLS AND NO OTHER ACFT WERE ON THE FREQ. WE TOOK RWY 17 FOR TKOF. WE PERFORMED THE NORMAL CLBOUT. THE FO WAS FLYING AND I; THE CAPT; WAS THE PNF. WHEN I CONTACTED DEP. HE WAS SURPRISED TO HEAR FROM US AND ASKED IF WE WERE VFR. I THOUGHT HE WAS ASKING IF WE WERE GOING TO FLY TO ZZZ1 UNDER VFR FLT PLAN. I REPLIED; 'NO; WE HAVE AN IFR CLRNC TO ZZZ1.' I MEANT WE WERE ON AN IFR FLT PLAN AND HAD OUR CLRNC TO ZZZ1 AND NOT OPERATING VFR TO ZZZ1. I INTENDED TO PICK UP RADAR CONTACT WITH HIM AT THAT TIME TO CONTINUE ENRTE IFR AFTER A VFR TKOF. THERE WAS A CESSNA IN OPPOSITE DIRECTION ON A PRACTICE VISUAL APCH S OF THE ARPT. THROUGH RADIO COM WITH ATC; THE OTHER ACFT; AND TCAS; WE WERE ABLE TO MAINTAIN VFR AND MAINTAIN ADEQUATE SEPARATION VERTLY AND LATERALLY WITHOUT ANY EVASIVE ACTION TAKEN. I TOLD DEP WE WERE VFR AND WOULD STAY VFR UNTIL WE WERE CLEAR OF THE CONFLICT. NEITHER ACFT WERE IN ATC'S RADAR COVERAGE. ATC SAID WE HAD A DEV AND WANTED US TO CONTACT THEM ON THE GND. WHEN I CONTACTED THEM; I WAS TOLD THEY WOULD BE FILLING PAPERWORK WITH THE FAA ABOUT THE INCIDENT. THEY TOLD ME THERE HAS BEEN A TREND LATELY WITH AIRLINE CREWS MISREADING BACK CLRNCS AND HAVING DEVS OCCUR. THEY SAID THEY WANTED TO MAKE THIS KNOWN TO THE COMPANY WITH OUR EXAMPLE. ATC ALSO SEEMED TO INTERP MY ANSWER THAT WE HAD AN 'IFR CLRNC' TO MEAN I WAS ALREADY IFR. THE COMPANY POLICY DOES NOT MAKE IT MANDATORY FOR BOTH PLTS TO BE PRESENT WHEN CALLING FOR A CLRNC. IT DOES STATE THAT THE CLRNC SHOULD BE VERIFIED WITH THE FILED FLT PLAN FOR ROUTING PURPOSES. WE REVIEWED THE CLRNC BUT THE 'HOLD FOR RELEASE' WAS NOT SOMETHING I FATHOMED TO QUESTION SINCE IT WAS NOT WRITTEN ON THE PAPER OR MENTIONED IN OUR BRIEFS. IF I WAS PRESENT DURING THE TIME HE GOT THE CLRNC; I WOULD HAVE HEARD THAT STATEMENT FROM THE CTLR.