Narrative:

Air carrier X about 120 NM north of tlh on J43 at FL230, en route to tlh from atz. I heard a couple of scratchy xmissions, and then heard our numbers. The controller sounded pretty excited, and told us to descend to FL220. The aircraft, an light transport was on autoplt and I hit the descent mode. The controller said we had traffic at 2 O'clock and 3 mi nebnd at FL230. Within seconds, we had the traffic, a large mlt Y. When we were descending through 22500', the controled asked us to verify we were at FL220. The captain told him we were leveling at FL220 and head the traffic in sight. The controled came back and said 'when I say descend, I mean now, not 5 mins later!' the captain replied that we had started down when he told us to and that his xmissions were very scratchy. One or two other pilots in different aircraft also told the controller at this time that his xmissions were scratchy. When we were clear of the traffic, the controller had us climb back to FL230. The controller obviously was caught off guard by two converging aircraft at the same altitude. Maybe an alarm went off. Probably one reason he was difficult to understand is that he was so excited. He obviously waited too late to contact us, but if he was having trouble getting us, why didn't he tell the other aircraft to descend? When the controller had first tried to contact us, I was just sitting there monitoring the aircraft. But perhaps if I had been more alert, I would have caught his first transmission. But alertness is hard to achieve after being on duty the previous day for 15 hours and flying over 8 hours in bad WX. With only an 8 hour overnight and into. Our 8TH hour of duty on this day, even staying awake can be a challenge.

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Original NASA ASRS Text

Title: ACR X HAD LESS THAN STANDARD SEPARATION FROM MLT Y. SYSTEM ERROR.

Narrative: ACR X ABOUT 120 NM N OF TLH ON J43 AT FL230, ENRTE TO TLH FROM ATZ. I HEARD A COUPLE OF SCRATCHY XMISSIONS, AND THEN HEARD OUR NUMBERS. THE CTLR SOUNDED PRETTY EXCITED, AND TOLD US TO DSND TO FL220. THE ACFT, AN LTT WAS ON AUTOPLT AND I HIT THE DSNT MODE. THE CTLR SAID WE HAD TFC AT 2 O'CLOCK AND 3 MI NEBND AT FL230. WITHIN SECS, WE HAD THE TFC, A LARGE MLT Y. WHEN WE WERE DSNDING THROUGH 22500', THE CTLED ASKED US TO VERIFY WE WERE AT FL220. THE CAPT TOLD HIM WE WERE LEVELING AT FL220 AND HEAD THE TFC IN SIGHT. THE CTLED CAME BACK AND SAID 'WHEN I SAY DSND, I MEAN NOW, NOT 5 MINS LATER!' THE CAPT REPLIED THAT WE HAD STARTED DOWN WHEN HE TOLD US TO AND THAT HIS XMISSIONS WERE VERY SCRATCHY. ONE OR TWO OTHER PLTS IN DIFFERENT ACFT ALSO TOLD THE CTLR AT THIS TIME THAT HIS XMISSIONS WERE SCRATCHY. WHEN WE WERE CLR OF THE TFC, THE CTLR HAD US CLB BACK TO FL230. THE CTLR OBVIOUSLY WAS CAUGHT OFF GUARD BY TWO CONVERGING ACFT AT THE SAME ALT. MAYBE AN ALARM WENT OFF. PROBABLY ONE REASON HE WAS DIFFICULT TO UNDERSTAND IS THAT HE WAS SO EXCITED. HE OBVIOUSLY WAITED TOO LATE TO CONTACT US, BUT IF HE WAS HAVING TROUBLE GETTING US, WHY DIDN'T HE TELL THE OTHER ACFT TO DSND? WHEN THE CTLR HAD FIRST TRIED TO CONTACT US, I WAS JUST SITTING THERE MONITORING THE ACFT. BUT PERHAPS IF I HAD BEEN MORE ALERT, I WOULD HAVE CAUGHT HIS FIRST XMISSION. BUT ALERTNESS IS HARD TO ACHIEVE AFTER BEING ON DUTY THE PREVIOUS DAY FOR 15 HRS AND FLYING OVER 8 HRS IN BAD WX. WITH ONLY AN 8 HR OVERNIGHT AND INTO. OUR 8TH HR OF DUTY ON THIS DAY, EVEN STAYING AWAKE CAN BE A CHALLENGE.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.