Narrative:

I was working towards the end of a 10 hour overtime shift. We were extremely understaffed this night; with no supervisor on the shift. The shift was published 2 under the number with the supervisor previously assigned to the shift approved to go on a detail. The shift ended up 4 controllers under staffed. Towards the end of my 10 hour overtime shift we had several controllers; myself included that needed to be relieved from their position because it was the end of their shift. We had to combine sectors to be able to get people up for the end of shift. After combining the sectors I had aircraft X landing. I then issue a crossing restriction of 65 NM west of a fix at 27000 feet. After reviewing the tapes; it turned out I missed the read back of 25000 feet instead of 27000 feet. Then it was my turn to be relieved from position. During my relief overlap time I'm watching my relieving controller take a handoff on aircraft Y climbing to 26000 feet opposite direction of aircraft X. The controller issued a traffic call to aircraft X and aircraft Y with more than 15 miles. Aircraft X initially acknowledged the call without question. After a few seconds aircraft X got an RA to climb and then questioned the traffic call. The relieving controller took action to reestablish positive separation. Controllers at the end of a 10 hour shift should probably not be working combined sectors with above average volume and complexity. There should be supervision on every shift to monitor these type of scenarios. The pilots should have questioned a traffic call with an aircraft climbing through his altitude.

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Original NASA ASRS Text

Title: Center Controllers reported an aircraft conflict due to a missed altitude assignment read back at the end of a 10 hour shift.

Narrative: I was working towards the end of a 10 hour overtime shift. We were extremely understaffed this night; with no supervisor on the shift. The shift was published 2 under the number with the Supervisor previously assigned to the shift approved to go on a detail. The shift ended up 4 controllers under staffed. Towards the end of my 10 hour overtime shift we had several controllers; myself included that needed to be relieved from their position because it was the end of their shift. We had to combine sectors to be able to get people up for the end of shift. After combining the sectors I had Aircraft X landing. I then issue a crossing restriction of 65 NM W of a fix at 27000 feet. After reviewing the tapes; it turned out I missed the read back of 25000 feet instead of 27000 feet. Then it was my turn to be relieved from position. During my relief overlap time I'm watching my relieving controller take a handoff on Aircraft Y climbing to 26000 feet opposite direction of Aircraft X. The controller issued a traffic call to Aircraft X and Aircraft Y with more than 15 miles. Aircraft X initially acknowledged the call without question. After a few seconds Aircraft X got an RA to climb and then questioned the traffic call. The relieving controller took action to reestablish positive separation. Controllers at the end of a 10 hour shift should probably not be working combined sectors with above average volume and complexity. There should be supervision on every shift to monitor these type of scenarios. The Pilots should have questioned a traffic call with an aircraft climbing through his altitude.

Data retrieved from NASA's ASRS site 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.