ACR X HAD LTSS FROM ACR Y. SYS ERROR. ACR Y FLC NON ADHERENCE TO ATC CLRNC FAILED TO CLB OR TURN. PLTDEV.

Narrative

DUE TO DEVELOPING TSTMS; ACFT WERE DEVIATING THROUGHOUT THE AREA. ACR X AT FL310; WAS TRAVELING WBOUND ON J6 TOWARD BWG AND ACR Y AT FL310; WAS TRAVELING NBOUND ON J89 TOWARD IIU. ACR X HAD BEGUN TO DEV TO THE S AROUND WX AND HAD BEEN CLRED TO DO SO BY THE RADAR CTLR. AT SOME POINT; WHILE I WAS NOT MONITORING THE FREQ DUE TO OTHER DEMANDS; THE RADAR CTLR ALSO CLRED ACR Y TO DEV L OR R OF COURSE AS NECESSARY. UPON HEARING THE CTLR DSND ACR X TO FL290; I RETURNED MY FOCUS TO THE RADAR SCOPE AT WHICH TIME I OBSERVED THAT THE 2 ACFT WERE HEAD-ON APPROX 15-20 MI APART AS ACR Y HAD MADE A 90 DEG PLUS TURN. I SUGGESTED TO THE RADAR CTLR THAT HE COULD CLB ACR Y TO FL330; WHICH HE DID. HE ALSO ASKED ACR Y TO TURN L IF FEASIBLE. THE PLT REPLIED THAT HE COULD MAKE A L TURN; HOWEVER; I NEVER OBSERVED A TURN BEFORE SEPARATION WAS LOST. ACR X WAS EVENTUALLY DSNDED TO FL270; AND WAS ASKED TO RPT LEAVING FL290 BUT VERT SEPARATION WAS NOT ACHIEVED BEFORE LATERAL SEPARATION WAS LOST. BECAUSE THE PLT OF AN ACFT HAS THE FINAL SAY AS TO WHERE OR WHEN HE WILL TURN THE ACFT FOR WX (OR ANY REASON FOR THAT MATTER); THE ONLY RECOMMENDATION I COULD MAKE FOR THIS TYPE OF SITUATION IS: WHEN AN ACFT ADVISES THAT DEVS WILL BE NECESSARY; THE CTLR SHOULD ASK THE PLT WHICH DIRECTION HE WILL DEV; CHK FOR POTENTIAL TFC AND THEN ASSIGN A SPECIFIC CLRNC TO DEV. FOR EXAMPLE; '...CLRED TO DEV 20 DEG R OR L OF COURSE. ADVISE CENTER IF FURTHER DEVS WILL BE NECESSARY.' IN OTHER WORDS; TIE DOWN DEVS AND DON'T MAKE ASSUMPTIONS BASED ON PREVIOUS ACFT DEVS.