A CARJ CREW; DISTR BY A PROBE HEAT MALFUNCTION; OVERSHOT AMENDED ALT.

Narrative

WE DEPARTED AT XA00 FOR A FINAL LEG OF THE DAY. THE CAPT WAS PF WHILE THE FO WAS ASSUMING THE PNF DUTIES. THE WX AT DEP WAS GOOD WITH VISIBILITY AND ABOUT 3500 FT OVCST WITH TOPS ABOUT 4500 AND CLR ABOVE. SHORTLY AFTER TKOF WE RECEIVED 3 CAUTION MESSAGES INDICATING THAT THE PROBE HEAT ON THE R SIDE OF THE ACFT HAD MALFUNCTIONED. IN ACCORDANCE WITH COMPANY PROC; THE PF ASSUMED THE RADIO DUTIES WHILE THE PNF COMPLETED THE QRH PROCS. THE PNF COMPLETED THE QRH PROCS WITH NO EFFECTIVE SOLUTION. BOTH PLTS WERE DISCUSSING POSSIBLE ISSUES OF WHETHER OR NOT WE COULD CONTINUE TO THE DEST OR WERE REQUIRED TO RETURN TO THE DEP ARPT. A DECISION WAS MADE TO CALL COMPANY MAINT FOR ASSISTANCE IN CLRING THE MALFUNCTIONS. AFTER SEVERAL MINS ON THE RADIO WITH MAINT THE MALFUNCTIONS WERE CLRED AND WE DECIDED WE COULD CONTINUE TO THE DEST. AFTER THE PROB WAS SOLVED; WE WERE CLBING THROUGH FL287 ABOUT TO LEVEL OFF AT FL290 WHEN ZAU ASKED US TO 'SAY ALT' AND ASKED WHETHER WE HAD BEEN CLRED ONLY TO FL280. WE VERIFIED THAT THEY DID NEED US AT FL280 AND IMMEDIATELY DSNDED TO FL280. WITHIN A MIN WE WERE CLRED TO CLB TO FINAL CRUISE ALT. UPON LNDG AT OUR DEST ARPT; WE TELEPHONED ZAU TO CLARIFY EXACTLY WHAT HAD HAPPENED IN THE CLB. A SUPVR IN CHICAGO STATED THAT WE HAD BEEN WITHIN 1300 FT VERTLY AND BTWN 4-5 MI HORIZLY TO ANOTHER ACFT; WHICH WAS LESS THAN THE REQUIRED CLRNC IN THAT SECTOR. BOTH PLTS REMEMBERED RECEIVING A CLRNC TO FL290 BUT NEITHER COULD RECALL A LATER RESTR TO FL280. THE CTR HAD REPLAYED THE TAPES OF THE SECTOR RADIO COMS AND 3 DIFFERENT PEOPLE WHO HEARD THE TAPES CONFIRMED THAT ONE OF US HAD ACCEPTED THE CLRNC. IN RETROSPECT; WHILE HANDLING THE MALFUNCTION WE SHOULD HAVE RELAYED OUR CONDITION TO DEP AND CTR; HAD THE CTLR KNOWN WE WERE DISTR WITH MECHANICAL DIFFICULTIES HE COULD HAVE POSSIBLY PROVIDED SIMPLER ROUTING AND CLB. IT SEEMS OBVIOUS NOW THAT WE BOTH BECAME TOO DISTR RUNNING THE QRH AND DIAGNOSING THE PROB. SUPPLEMENTAL INFO FROM ACN 535436: CTR INFORMED US OF THE NEED TO FILL OUT A RPT AND FORWARD IT TO THE FSDO. THEY TOLD ME THE REASON FOR THE AMENDED ALT WAS FOR TFC; AND AT THE TIME WE WERE CALLED BY CTR TO 'MAINTAIN FL280' WE WERE AT FL287 AND ANOTHER ACFT WAS AT FL303 AND CLBING. LATERAL SEPARATION WAS 4-5 MI.