ACR X HAD LTSS FROM ACR Y SAME ALT ASSIGNED. EVASIVE ACTION TAKEN. SYS ERROR.

Narrative

AS ACR X APCHED STN (APPROX 2 MI); I LOOKED UP TO SEE AN ACR Y AT OUR 2 O'CLOCK; SLIGHTLY ABOVE THE HORIZON. RANGE ABOUT 2 MI. ACR X HAD JUST STARTED ITS TURN TOWARD 5910N. THE FO STEEPENED THE TURN WITH HDG SELECT. SIMULTANEOUSLY; SCOTTISH CTR CALLED BOTH US AND ACR Y WITH NEW HDGS. (270 DEGS FOR US). ACR Y MAY HAVE BEEN IN A CLB AS HE APPEARED SLIGHTLY HIGHER THAN US. THE FO DIDN'T SEE ACR Y BECAUSE IT WAS BEHIND HIS WINDSHIELD POST. I NEVER SAW HIM AGAIN! TCASII IS NOT INSTALLED ON THIS WDB YET; IT WOULD HAVE BEEN VERY HANDY! SCOTTISH PREVIOUSLY HAD TRIED TO SEND US DIRECT TO 5910N; BUT WE HAD TO LOSE 5 MINS FOR THE COASTOUT SLOT; SO WE STAYED ON COURSE TO STORNOWAY; WITH HIS CONCURRENCE. SUPPLEMENTAL INFO FROM ACN 224828: WHILE XING STN AND STARTING A TURN (TO THE L) TOWARD THE NEXT ENRTE FIX (N5900W1000); THE CAPT NOTICED AN ACR OFF OUR R SIDE AT APPROX THE SAME ALT AND AN ESTIMATED 2 MI AWAY AND ABOUT THE SAME DIRECTION. HE BROUGHT IT TO OUR ATTN AND WE BOTH REACHED FOR THE CTLS. AT APPROX THE SAME TIME; THE CTLR ISSUED HDG CHANGES FOR BOTH ACFT; ACR TO THE R AND US TO THE L. BY THAT TIME; WE HAD ALREADY INITIATED A L TURN ON OUR OWN. I HAD REACHED UP AND PLACED THE AUTOPLT IN HDG MODE AND ROTATED THE HDG BUG; AND BELIEVE IT MADE THE TURN SINCE IT DID NOT DISENGAGE. WE SAW ACR MAKING THE R TURN AT ABOUT THE SAME TIME AND INCREASED SEPARATION OCCURRED IN A VERY SHORT TIME. EVASIVE ACTION WAS TAKEN BUT BY MEANS OF A NORMAL TURN. FACTORS THAT HAD KEPT US OUT OF THE 'ROUTINE' UP UNTIL THAT POINT WERE: 1. STARTING FROM TKOF AND THROUGH ALL PHASES OF FLT; THE THROTTLE LEVERS WERE 'ABNORMALLY' OUT OF RIG WHICH WAS A MINOR DISTR BUT STILL DISTRACTING. 2. WHEN WE COMPLETED THE NAV ACCURACY CHK; THERE WAS A LITTLE MORE THAN THE NORMAL ERROR FOR SUCH A SHORT DURATION OF FLT. NOT ENOUGH TO BE CONSIDERED UNRELIABLE BUT A TOPIC FOR SOME DISCUSSION. UPON RECEIVING OUR OCEANIC CLRNC; WE HAD A CHANGE IN RTE WHICH RESULTED IN RE-DOING THE FMS PROGRAM; PLOTTING CHARTS; TIME ESTIMATES; ETC. 4. ATC ATTEMPTED TO CLR US DIRECT TO N5900W1000 SOME TIME PRIOR TO REACHING STN. HOWEVER; SINCE THAT WOULD HAVE PUT US AT 5910 SEVERAL MINS BEFORE OUR CLRNC 'NOT BEFORE TIME;' WE REQUESTED AND RECEIVED CLRNC TO PROCEED VIA FLT PLAN RTE. SUPPLEMENTAL INFO FROM ACN 225941: CAPT POINTED OUT CONVERGING TFC FROM OUR 3 O'CLOCK POS. HE INCREASED OUR RATE OF TURN (BANK ANGLE) IN ORDER TO INCREASE SEPARATION. AT THE SAME TIME; THE OTHER ACFT INITIATED ITS TURN AWAY; TO ITS NEXT POINT. ALSO; SIMULTANEOUSLY WITH THESE EVENTS; CTR CALLED WITH RADAR VECTORS TO EACH ACFT.