B757 FLC ACCEPT ZDV CLB CLRNC FROM FL370 TO FL410 BUT DO NOT LEVEL WITHIN COORD TIME PERIOD AND ARE INVOLVED IN A CONFLICT.

Narrative

WHILE OPERATING A B757; CRUISING AT FL370; EXPERIENCING CONTINUOUS LIGHT TURB; WE REQUESTED FL410. ATC ASKED HOW LONG IT WOULD TAKE TO CLB TO FL410. WE RESPONDED '4 MINS.' AFTER A SHORT DELAY; ATC REPLIED 'CLB AND MAINTAIN FL410 AND TIME NOW XX01; BE AT FL410 AT XX05.' WE NOTED OUR CLOCK ALSO REFLECTED THE TIME AS XX01 AND INITIATED AN IMMEDIATE VNAV CLB AT FULL CLB THRUST WITH AN AVERAGE RATE OF CLB AT OR GREATER THAN 1000 FPM. AS WE APCHED FL410; WE HEARD ATC TURN AN ACFT 30 DEGS TO THE L (OUR R). WE HAD THAT TFC BELOW US IN SIGHT AT 12 - 1 O'CLOCK POS; REF OUR ACFT. ATC ASKED OUR ALT AND WE RESPONDED FL408; NOTING OUR CLOCK AT XX04. A COUPLE SECONDS LATER; WE RPTED LEVEL AT FL410; NOTING OUR CLOCK AT XX05; AND REMAINED THERE FOR SOME TIME THEREAFTER. THE FINAL XMISSION WITH ATC (ZDV) WAS AN ADVISEMENT OF A POSSIBLE PLTDEV AND GAVE US A PHONE NUMBER TO CALL; SWITCHED US TO ZMP. WE WERE UNABLE TO DETERMINE PRECISELY THE EXACT NUMBER OF SECONDS WHICH ELAPSED BTWN OUR RECEIPT OF THE CLB CLRNC AND OUR LEVELING AT FL410. IN SUMMATION; IT APPEARED BY ALL AVAILABLE INFO THAT WE HAD COMPLIED WITH THE ATC INSTRUCTIONS/CLRNC. SUPPLEMENTAL INFO FROM ACN 510878: MY LUNCH HAD JUST BEEN BROUGHT TO THE COCKPIT AND I HAD PASSED CTL OF THE ACFT TO THE CAPT. I SELECTED FL410 ON THE FMS CRUISE PAGE AND THE ACFT BEGAN CLBING AT APPROX 1400 FPM. I THEN RETURNED TO EATING MY LUNCH BUT MONITORED THE CLB. AT APPROX FL400; THE CLB RATE FELL OFF TO JUST UNDER 1000 FPM AND THE CAPT USED VERT SPD TO RESUME 1000 FPM OR GREATER. AT APPROX THE SAME TIME WE HEARD ZDV VECTOR AN AIRLINE FLT; TURNING THEM L FOR TFC. I NOTED OUR CLOCK WAS STILL READING XX04 AT THAT TIME. SHORTLY AFTER REACHING FL410; THE CAPT RPTED LEVEL AT FL410. THE CLOCK HAD JUST TURNED OVER TO XX05 AT THAT TIME. IN THE PHONE CALL TO ZDV; THE CTLR INDICATED IT HAD TAKEN US 4 MINS AND SEVERAL SECONDS TO REACH FL410. CTR ADVISED THAT SEPARATION HAD BEEN LOST BTWN US AND THE FLT WE HAD OBSERVED TO OUR R. CTR RPTED THAT WE HAD 1800 FT VERT SEPARATION AND 3.5 MI LATERAL SEPARATION. RECOMMENDATIONS FOR PREVENTING RECURRENCE: 1) EDUCATE PLTS THAT WHILE ATC MAY ISSUE AN INSTRUCTION/CLRNC IN MINS; THAT THEY MAY BE PLANNING SEPARATION IN SECONDS. 2) AVOID ACCEPTING ANY INSTRUCTION/CLRNC BASED ON TIME UNLESS THE TIME STANDARD IS CLRLY UNDERSTOOD. 3) BE VERY CONSERVATIVE IN ESTIMATING ANY TIME BASED ON ACFT PERFORMANCE.